JDK8/Java8源码在线阅读
/*
* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.sql.rowset;
import java.sql.*;
import javax.sql.*;
import javax.naming.*;
import java.io.*;
import java.math.*;
import java.util.*;
import javax.sql.rowset.spi.*;
/**
* The interface that all standard implementations of
* <code>CachedRowSet</code> must implement.
* <P>
* The reference implementation of the <code>CachedRowSet</code> interface provided
* by Oracle Corporation is a standard implementation. Developers may use this implementation
* just as it is, they may extend it, or they may choose to write their own implementations
* of this interface.
* <P>
* A <code>CachedRowSet</code> object is a container for rows of data
* that caches its rows in memory, which makes it possible to operate without always being
* connected to its data source. Further, it is a
* JavaBeans™ component and is scrollable,
* updatable, and serializable. A <code>CachedRowSet</code> object typically
* contains rows from a result set, but it can also contain rows from any file
* with a tabular format, such as a spread sheet. The reference implementation
* supports getting data only from a <code>ResultSet</code> object, but
* developers can extend the <code>SyncProvider</code> implementations to provide
* access to other tabular data sources.
* <P>
* An application can modify the data in a <code>CachedRowSet</code> object, and
* those modifications can then be propagated back to the source of the data.
* <P>
* A <code>CachedRowSet</code> object is a <i>disconnected</i> rowset, which means
* that it makes use of a connection to its data source only briefly. It connects to its
* data source while it is reading data to populate itself with rows and again
* while it is propagating changes back to its underlying data source. The rest
* of the time, a <code>CachedRowSet</code> object is disconnected, including
* while its data is being modified. Being disconnected makes a <code>RowSet</code>
* object much leaner and therefore much easier to pass to another component. For
* example, a disconnected <code>RowSet</code> object can be serialized and passed
* over the wire to a thin client such as a personal digital assistant (PDA).
*
*
* <h3>1.0 Creating a <code>CachedRowSet</code> Object</h3>
* The following line of code uses the default constructor for
* <code>CachedRowSet</code>
* supplied in the reference implementation (RI) to create a default
* <code>CachedRowSet</code> object.
* <PRE>
* CachedRowSetImpl crs = new CachedRowSetImpl();
* </PRE>
* This new <code>CachedRowSet</code> object will have its properties set to the
* default properties of a <code>BaseRowSet</code> object, and, in addition, it will
* have an <code>RIOptimisticProvider</code> object as its synchronization provider.
* <code>RIOptimisticProvider</code>, one of two <code>SyncProvider</code>
* implementations included in the RI, is the default provider that the
* <code>SyncFactory</code> singleton will supply when no synchronization
* provider is specified.
* <P>
* A <code>SyncProvider</code> object provides a <code>CachedRowSet</code> object
* with a reader (a <code>RowSetReader</code> object) for reading data from a
* data source to populate itself with data. A reader can be implemented to read
* data from a <code>ResultSet</code> object or from a file with a tabular format.
* A <code>SyncProvider</code> object also provides
* a writer (a <code>RowSetWriter</code> object) for synchronizing any
* modifications to the <code>CachedRowSet</code> object's data made while it was
* disconnected with the data in the underlying data source.
* <P>
* A writer can be implemented to exercise various degrees of care in checking
* for conflicts and in avoiding them.
* (A conflict occurs when a value in the data source has been changed after
* the rowset populated itself with that value.)
* The <code>RIOptimisticProvider</code> implementation assumes there will be
* few or no conflicts and therefore sets no locks. It updates the data source
* with values from the <code>CachedRowSet</code> object only if there are no
* conflicts.
* Other writers can be implemented so that they always write modified data to
* the data source, which can be accomplished either by not checking for conflicts
* or, on the other end of the spectrum, by setting locks sufficient to prevent data
* in the data source from being changed. Still other writer implementations can be
* somewhere in between.
* <P>
* A <code>CachedRowSet</code> object may use any
* <code>SyncProvider</code> implementation that has been registered
* with the <code>SyncFactory</code> singleton. An application
* can find out which <code>SyncProvider</code> implementations have been
* registered by calling the following line of code.
* <PRE>
* java.util.Enumeration providers = SyncFactory.getRegisteredProviders();
* </PRE>
* <P>
* There are two ways for a <code>CachedRowSet</code> object to specify which
* <code>SyncProvider</code> object it will use.
* <UL>
* <LI>Supplying the name of the implementation to the constructor<BR>
* The following line of code creates the <code>CachedRowSet</code>
* object <i>crs2</i> that is initialized with default values except that its
* <code>SyncProvider</code> object is the one specified.
* <PRE>
* CachedRowSetImpl crs2 = new CachedRowSetImpl(
* "com.fred.providers.HighAvailabilityProvider");
* </PRE>
* <LI>Setting the <code>SyncProvider</code> using the <code>CachedRowSet</code>
* method <code>setSyncProvider</code><BR>
* The following line of code resets the <code>SyncProvider</code> object
* for <i>crs</i>, the <code>CachedRowSet</code> object created with the
* default constructor.
* <PRE>
* crs.setSyncProvider("com.fred.providers.HighAvailabilityProvider");
* </PRE>
* </UL>
* See the comments for <code>SyncFactory</code> and <code>SyncProvider</code> for
* more details.
*
*
* <h3>2.0 Retrieving Data from a <code>CachedRowSet</code> Object</h3>
* Data is retrieved from a <code>CachedRowSet</code> object by using the
* getter methods inherited from the <code>ResultSet</code>
* interface. The following examples, in which <code>crs</code> is a
* <code>CachedRowSet</code>
* object, demonstrate how to iterate through the rows, retrieving the column
* values in each row. The first example uses the version of the
* getter methods that take a column number; the second example
* uses the version that takes a column name. Column numbers are generally
* used when the <code>RowSet</code> object's command
* is of the form <code>SELECT * FROM TABLENAME</code>; column names are most
* commonly used when the command specifies columns by name.
* <PRE>
* while (crs.next()) {
* String name = crs.getString(1);
* int id = crs.getInt(2);
* Clob comment = crs.getClob(3);
* short dept = crs.getShort(4);
* System.out.println(name + " " + id + " " + comment + " " + dept);
* }
* </PRE>
*
* <PRE>
* while (crs.next()) {
* String name = crs.getString("NAME");
* int id = crs.getInt("ID");
* Clob comment = crs.getClob("COM");
* short dept = crs.getShort("DEPT");
* System.out.println(name + " " + id + " " + comment + " " + dept);
* }
* </PRE>
* <h4>2.1 Retrieving <code>RowSetMetaData</code></h4>
* An application can get information about the columns in a <code>CachedRowSet</code>
* object by calling <code>ResultSetMetaData</code> and <code>RowSetMetaData</code>
* methods on a <code>RowSetMetaData</code> object. The following code fragment,
* in which <i>crs</i> is a <code>CachedRowSet</code> object, illustrates the process.
* The first line creates a <code>RowSetMetaData</code> object with information
* about the columns in <i>crs</i>. The method <code>getMetaData</code>,
* inherited from the <code>ResultSet</code> interface, returns a
* <code>ResultSetMetaData</code> object, which is cast to a
* <code>RowSetMetaData</code> object before being assigned to the variable
* <i>rsmd</i>. The second line finds out how many columns <i>jrs</i> has, and
* the third line gets the JDBC type of values stored in the second column of
* <code>jrs</code>.
* <PRE>
* RowSetMetaData rsmd = (RowSetMetaData)crs.getMetaData();
* int count = rsmd.getColumnCount();
* int type = rsmd.getColumnType(2);
* </PRE>
* The <code>RowSetMetaData</code> interface differs from the
* <code>ResultSetMetaData</code> interface in two ways.
* <UL>
* <LI><i>It includes <code>setter</code> methods:</i> A <code>RowSet</code>
* object uses these methods internally when it is populated with data from a
* different <code>ResultSet</code> object.
*
* <LI><i>It contains fewer <code>getter</code> methods:</i> Some
* <code>ResultSetMetaData</code> methods to not apply to a <code>RowSet</code>
* object. For example, methods retrieving whether a column value is writable
* or read only do not apply because all of a <code>RowSet</code> object's
* columns will be writable or read only, depending on whether the rowset is
* updatable or not.
* </UL>
* NOTE: In order to return a <code>RowSetMetaData</code> object, implementations must
* override the <code>getMetaData()</code> method defined in
* <code>java.sql.ResultSet</code> and return a <code>RowSetMetaData</code> object.
*
* <h3>3.0 Updating a <code>CachedRowSet</code> Object</h3>
* Updating a <code>CachedRowSet</code> object is similar to updating a
* <code>ResultSet</code> object, but because the rowset is not connected to
* its data source while it is being updated, it must take an additional step
* to effect changes in its underlying data source. After calling the method
* <code>updateRow</code> or <code>insertRow</code>, a
* <code>CachedRowSet</code>
* object must also call the method <code>acceptChanges</code> to have updates
* written to the data source. The following example, in which the cursor is
* on a row in the <code>CachedRowSet</code> object <i>crs</i>, shows
* the code required to update two column values in the current row and also
* update the <code>RowSet</code> object's underlying data source.
* <PRE>
* crs.updateShort(3, 58);
* crs.updateInt(4, 150000);
* crs.updateRow();
* crs.acceptChanges();
* </PRE>
* <P>
* The next example demonstrates moving to the insert row, building a new
* row on the insert row, inserting it into the rowset, and then calling the
* method <code>acceptChanges</code> to add the new row to the underlying data
* source. Note that as with the getter methods, the updater methods may take
* either a column index or a column name to designate the column being acted upon.
* <PRE>
* crs.moveToInsertRow();
* crs.updateString("Name", "Shakespeare");
* crs.updateInt("ID", 10098347);
* crs.updateShort("Age", 58);
* crs.updateInt("Sal", 150000);
* crs.insertRow();
* crs.moveToCurrentRow();
* crs.acceptChanges();
* </PRE>
* <P>
* NOTE: Where the <code>insertRow()</code> method inserts the contents of a
* <code>CachedRowSet</code> object's insert row is implementation-defined.
* The reference implementation for the <code>CachedRowSet</code> interface
* inserts a new row immediately following the current row, but it could be
* implemented to insert new rows in any number of other places.
* <P>
* Another thing to note about these examples is how they use the method
* <code>acceptChanges</code>. It is this method that propagates changes in
* a <code>CachedRowSet</code> object back to the underlying data source,
* calling on the <code>RowSet</code> object's writer internally to write
* changes to the data source. To do this, the writer has to incur the expense
* of establishing a connection with that data source. The
* preceding two code fragments call the method <code>acceptChanges</code>
* immediately after calling <code>updateRow</code> or <code>insertRow</code>.
* However, when there are multiple rows being changed, it is more efficient to call
* <code>acceptChanges</code> after all calls to <code>updateRow</code>
* and <code>insertRow</code> have been made. If <code>acceptChanges</code>
* is called only once, only one connection needs to be established.
*
* <h3>4.0 Updating the Underlying Data Source</h3>
* When the method <code>acceptChanges</code> is executed, the
* <code>CachedRowSet</code> object's writer, a <code>RowSetWriterImpl</code>
* object, is called behind the scenes to write the changes made to the
* rowset to the underlying data source. The writer is implemented to make a
* connection to the data source and write updates to it.
* <P>
* A writer is made available through an implementation of the
* <code>SyncProvider</code> interface, as discussed in section 1,
* "Creating a <code>CachedRowSet</code> Object."
* The default reference implementation provider, <code>RIOptimisticProvider</code>,
* has its writer implemented to use an optimistic concurrency control
* mechanism. That is, it maintains no locks in the underlying database while
* the rowset is disconnected from the database and simply checks to see if there
* are any conflicts before writing data to the data source. If there are any
* conflicts, it does not write anything to the data source.
* <P>
* The reader/writer facility
* provided by the <code>SyncProvider</code> class is pluggable, allowing for the
* customization of data retrieval and updating. If a different concurrency
* control mechanism is desired, a different implementation of
* <code>SyncProvider</code> can be plugged in using the method
* <code>setSyncProvider</code>.
* <P>
* In order to use the optimistic concurrency control routine, the
* <code>RIOptismisticProvider</code> maintains both its current
* value and its original value (the value it had immediately preceding the
* current value). Note that if no changes have been made to the data in a
* <code>RowSet</code> object, its current values and its original values are the same,
* both being the values with which the <code>RowSet</code> object was initially
* populated. However, once any values in the <code>RowSet</code> object have been
* changed, the current values and the original values will be different, though at
* this stage, the original values are still the initial values. With any subsequent
* changes to data in a <code>RowSet</code> object, its original values and current
* values will still differ, but its original values will be the values that
* were previously the current values.
* <P>
* Keeping track of original values allows the writer to compare the <code>RowSet</code>
* object's original value with the value in the database. If the values in
* the database differ from the <code>RowSet</code> object's original values, which means that
* the values in the database have been changed, there is a conflict.
* Whether a writer checks for conflicts, what degree of checking it does, and how
* it handles conflicts all depend on how it is implemented.
*
* <h3>5.0 Registering and Notifying Listeners</h3>
* Being JavaBeans components, all rowsets participate in the JavaBeans event
* model, inheriting methods for registering listeners and notifying them of
* changes from the <code>BaseRowSet</code> class. A listener for a
* <code>CachedRowSet</code> object is a component that wants to be notified
* whenever there is a change in the rowset. For example, if a
* <code>CachedRowSet</code> object contains the results of a query and
* those
* results are being displayed in, say, a table and a bar graph, the table and
* bar graph could be registered as listeners with the rowset so that they can
* update themselves to reflect changes. To become listeners, the table and
* bar graph classes must implement the <code>RowSetListener</code> interface.
* Then they can be added to the <Code>CachedRowSet</code> object's list of
* listeners, as is illustrated in the following lines of code.
* <PRE>
* crs.addRowSetListener(table);
* crs.addRowSetListener(barGraph);
* </PRE>
* Each <code>CachedRowSet</code> method that moves the cursor or changes
* data also notifies registered listeners of the changes, so
* <code>table</code> and <code>barGraph</code> will be notified when there is
* a change in <code>crs</code>.
*
* <h3>6.0 Passing Data to Thin Clients</h3>
* One of the main reasons to use a <code>CachedRowSet</code> object is to
* pass data between different components of an application. Because it is
* serializable, a <code>CachedRowSet</code> object can be used, for example,
* to send the result of a query executed by an enterprise JavaBeans component
* running in a server environment over a network to a client running in a
* web browser.
* <P>
* While a <code>CachedRowSet</code> object is disconnected, it can be much
* leaner than a <code>ResultSet</code> object with the same data.
* As a result, it can be especially suitable for sending data to a thin client
* such as a PDA, where it would be inappropriate to use a JDBC driver
* due to resource limitations or security considerations.
* Thus, a <code>CachedRowSet</code> object provides a means to "get rows in"
* without the need to implement the full JDBC API.
*
* <h3>7.0 Scrolling and Updating</h3>
* A second major use for <code>CachedRowSet</code> objects is to provide
* scrolling and updating for <code>ResultSet</code> objects that
* do not provide these capabilities themselves. In other words, a
* <code>CachedRowSet</code> object can be used to augment the
* capabilities of a JDBC technology-enabled driver (hereafter called a
* "JDBC driver") when the DBMS does not provide full support for scrolling and
* updating. To achieve the effect of making a non-scrollble and read-only
* <code>ResultSet</code> object scrollable and updatable, a programmer
* simply needs to create a <code>CachedRowSet</code> object populated
* with that <code>ResultSet</code> object's data. This is demonstrated
* in the following code fragment, where <code>stmt</code> is a
* <code>Statement</code> object.
* <PRE>
* ResultSet rs = stmt.executeQuery("SELECT * FROM EMPLOYEES");
* CachedRowSetImpl crs = new CachedRowSetImpl();
* crs.populate(rs);
* </PRE>
* <P>
* The object <code>crs</code> now contains the data from the table
* <code>EMPLOYEES</code>, just as the object <code>rs</code> does.
* The difference is that the cursor for <code>crs</code> can be moved
* forward, backward, or to a particular row even if the cursor for
* <code>rs</code> can move only forward. In addition, <code>crs</code> is
* updatable even if <code>rs</code> is not because by default, a
* <code>CachedRowSet</code> object is both scrollable and updatable.
* <P>
* In summary, a <code>CachedRowSet</code> object can be thought of as simply
* a disconnected set of rows that are being cached outside of a data source.
* Being thin and serializable, it can easily be sent across a wire,
* and it is well suited to sending data to a thin client. However, a
* <code>CachedRowSet</code> object does have a limitation: It is limited in
* size by the amount of data it can store in memory at one time.
*
* <h3>8.0 Getting Universal Data Access</h3>
* Another advantage of the <code>CachedRowSet</code> class is that it makes it
* possible to retrieve and store data from sources other than a relational
* database. The reader for a rowset can be implemented to read and populate
* its rowset with data from any tabular data source, including a spreadsheet
* or flat file.
* Because both a <code>CachedRowSet</code> object and its metadata can be
* created from scratch, a component that acts as a factory for rowsets
* can use this capability to create a rowset containing data from
* non-SQL data sources. Nevertheless, it is expected that most of the time,
* <code>CachedRowSet</code> objects will contain data that was fetched
* from an SQL database using the JDBC API.
*
* <h3>9.0 Setting Properties</h3>
* All rowsets maintain a set of properties, which will usually be set using
* a tool. The number and kinds of properties a rowset has will vary,
* depending on what the rowset does and how it gets its data. For example,
* rowsets that get their data from a <code>ResultSet</code> object need to
* set the properties that are required for making a database connection.
* If a rowset uses the <code>DriverManager</code> facility to make a
* connection, it needs to set a property for the JDBC URL that identifies
* the appropriate driver, and it needs to set the properties that give the
* user name and password.
* If, on the other hand, the rowset uses a <code>DataSource</code> object
* to make the connection, which is the preferred method, it does not need to
* set the property for the JDBC URL. Instead, it needs to set
* properties for the logical name of the data source, for the user name,
* and for the password.
* <P>
* NOTE: In order to use a <code>DataSource</code> object for making a
* connection, the <code>DataSource</code> object must have been registered
* with a naming service that uses the Java Naming and Directory
* Interface™ (JNDI) API. This registration
* is usually done by a person acting in the capacity of a system
* administrator.
* <P>
* In order to be able to populate itself with data from a database, a rowset
* needs to set a command property. This property is a query that is a
* <code>PreparedStatement</code> object, which allows the query to have
* parameter placeholders that are set at run time, as opposed to design time.
* To set these placeholder parameters with values, a rowset provides
* setter methods for setting values of each data type,
* similar to the setter methods provided by the <code>PreparedStatement</code>
* interface.
* <P>
* The following code fragment illustrates how the <code>CachedRowSet</code>
* object <code>crs</code> might have its command property set. Note that if a
* tool is used to set properties, this is the code that the tool would use.
* <PRE>{@code
* crs.setCommand("SELECT FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS " +
* "WHERE CREDIT_LIMIT > ? AND REGION = ?");
* } </PRE>
* <P>
* The values that will be used to set the command's placeholder parameters are
* contained in the <code>RowSet</code> object's <code>params</code> field, which is a
* <code>Vector</code> object.
* The <code>CachedRowSet</code> class provides a set of setter
* methods for setting the elements in its <code>params</code> field. The
* following code fragment demonstrates setting the two parameters in the
* query from the previous example.
* <PRE>
* crs.setInt(1, 5000);
* crs.setString(2, "West");
* </PRE>
* <P>
* The <code>params</code> field now contains two elements, each of which is
* an array two elements long. The first element is the parameter number;
* the second is the value to be set.
* In this case, the first element of <code>params</code> is
* <code>1</code>, <code>5000</code>, and the second element is <code>2</code>,
* <code>"West"</code>. When an application calls the method
* <code>execute</code>, it will in turn call on this <code>RowSet</code> object's reader,
* which will in turn invoke its <code>readData</code> method. As part of
* its implementation, <code>readData</code> will get the values in
* <code>params</code> and use them to set the command's placeholder
* parameters.
* The following code fragment gives an idea of how the reader
* does this, after obtaining the <code>Connection</code> object
* <code>con</code>.
* <PRE>{@code
* PreparedStatement pstmt = con.prepareStatement(crs.getCommand());
* reader.decodeParams();
* // decodeParams figures out which setter methods to use and does something
* // like the following:
* // for (i = 0; i < params.length; i++) {
* // pstmt.setObject(i + 1, params[i]);
* // }
* }</PRE>
* <P>
* At this point, the command for <code>crs</code> is the query {@code "SELECT
* FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS WHERE CREDIT_LIMIT > 5000
* AND REGION = "West"}. After the <code>readData</code> method executes
* this command with the following line of code, it will have the data from
* <code>rs</code> with which to populate <code>crs</code>.
* <PRE>{@code
* ResultSet rs = pstmt.executeQuery();
* }</PRE>
* <P>
* The preceding code fragments give an idea of what goes on behind the
* scenes; they would not appear in an application, which would not invoke
* methods like <code>readData</code> and <code>decodeParams</code>.
* In contrast, the following code fragment shows what an application might do.
* It sets the rowset's command, sets the command's parameters, and executes
* the command. Simply by calling the <code>execute</code> method,
* <code>crs</code> populates itself with the requested data from the
* table <code>CUSTOMERS</code>.
* <PRE>{@code
* crs.setCommand("SELECT FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS" +
* "WHERE CREDIT_LIMIT > ? AND REGION = ?");
* crs.setInt(1, 5000);
* crs.setString(2, "West");
* crs.execute();
* }</PRE>
*
* <h3>10.0 Paging Data</h3>
* Because a <code>CachedRowSet</code> object stores data in memory,
* the amount of data that it can contain at any one
* time is determined by the amount of memory available. To get around this limitation,
* a <code>CachedRowSet</code> object can retrieve data from a <code>ResultSet</code>
* object in chunks of data, called <i>pages</i>. To take advantage of this mechanism,
* an application sets the number of rows to be included in a page using the method
* <code>setPageSize</code>. In other words, if the page size is set to five, a chunk
* of five rows of
* data will be fetched from the data source at one time. An application can also
* optionally set the maximum number of rows that may be fetched at one time. If the
* maximum number of rows is set to zero, or no maximum number of rows is set, there is
* no limit to the number of rows that may be fetched at a time.
* <P>
* After properties have been set,
* the <code>CachedRowSet</code> object must be populated with data
* using either the method <code>populate</code> or the method <code>execute</code>.
* The following lines of code demonstrate using the method <code>populate</code>.
* Note that this version of the method takes two parameters, a <code>ResultSet</code>
* handle and the row in the <code>ResultSet</code> object from which to start
* retrieving rows.
* <PRE>
* CachedRowSet crs = new CachedRowSetImpl();
* crs.setMaxRows(20);
* crs.setPageSize(4);
* crs.populate(rsHandle, 10);
* </PRE>
* When this code runs, <i>crs</i> will be populated with four rows from
* <i>rsHandle</i> starting with the tenth row.
* <P>
* The next code fragment shows populating a <code>CachedRowSet</code> object using the
* method <code>execute</code>, which may or may not take a <code>Connection</code>
* object as a parameter. This code passes <code>execute</code> the <code>Connection</code>
* object <i>conHandle</i>.
* <P>
* Note that there are two differences between the following code
* fragment and the previous one. First, the method <code>setMaxRows</code> is not
* called, so there is no limit set for the number of rows that <i>crs</i> may contain.
* (Remember that <i>crs</i> always has the overriding limit of how much data it can
* store in memory.) The second difference is that the you cannot pass the method
* <code>execute</code> the number of the row in the <code>ResultSet</code> object
* from which to start retrieving rows. This method always starts with the first row.
* <PRE>
* CachedRowSet crs = new CachedRowSetImpl();
* crs.setPageSize(5);
* crs.execute(conHandle);
* </PRE>
* After this code has run, <i>crs</i> will contain five rows of data from the
* <code>ResultSet</code> object produced by the command for <i>crs</i>. The writer
* for <i>crs</i> will use <i>conHandle</i> to connect to the data source and
* execute the command for <i>crs</i>. An application is then able to operate on the
* data in <i>crs</i> in the same way that it would operate on data in any other
* <code>CachedRowSet</code> object.
* <P>
* To access the next page (chunk of data), an application calls the method
* <code>nextPage</code>. This method creates a new <code>CachedRowSet</code> object
* and fills it with the next page of data. For example, assume that the
* <code>CachedRowSet</code> object's command returns a <code>ResultSet</code> object
* <i>rs</i> with 1000 rows of data. If the page size has been set to 100, the first
* call to the method <code>nextPage</code> will create a <code>CachedRowSet</code> object
* containing the first 100 rows of <i>rs</i>. After doing what it needs to do with the
* data in these first 100 rows, the application can again call the method
* <code>nextPage</code> to create another <code>CachedRowSet</code> object
* with the second 100 rows from <i>rs</i>. The data from the first <code>CachedRowSet</code>
* object will no longer be in memory because it is replaced with the data from the
* second <code>CachedRowSet</code> object. After the tenth call to the method <code>nextPage</code>,
* the tenth <code>CachedRowSet</code> object will contain the last 100 rows of data from
* <i>rs</i>, which are stored in memory. At any given time, the data from only one
* <code>CachedRowSet</code> object is stored in memory.
* <P>
* The method <code>nextPage</code> returns <code>true</code> as long as the current
* page is not the last page of rows and <code>false</code> when there are no more pages.
* It can therefore be used in a <code>while</code> loop to retrieve all of the pages,
* as is demonstrated in the following lines of code.
* <PRE>
* CachedRowSet crs = CachedRowSetImpl();
* crs.setPageSize(100);
* crs.execute(conHandle);
*
* while(crs.nextPage()) {
* while(crs.next()) {
* . . . // operate on chunks (of 100 rows each) in crs,
* // row by row
* }
* }
* </PRE>
* After this code fragment has been run, the application will have traversed all
* 1000 rows, but it will have had no more than 100 rows in memory at a time.
* <P>
* The <code>CachedRowSet</code> interface also defines the method <code>previousPage</code>.
* Just as the method <code>nextPage</code> is analogous to the <code>ResultSet</code>
* method <code>next</code>, the method <code>previousPage</code> is analogous to
* the <code>ResultSet</code> method <code>previous</code>. Similar to the method
* <code>nextPage</code>, <code>previousPage</code> creates a <code>CachedRowSet</code>
* object containing the number of rows set as the page size. So, for instance, the
* method <code>previousPage</code> could be used in a <code>while</code> loop at
* the end of the preceding code fragment to navigate back through the pages from the last
* page to the first page.
* The method <code>previousPage</code> is also similar to <code>nextPage</code>
* in that it can be used in a <code>while</code>
* loop, except that it returns <code>true</code> as long as there is another page
* preceding it and <code>false</code> when there are no more pages ahead of it.
* <P>
* By positioning the cursor after the last row for each page,
* as is done in the following code fragment, the method <code>previous</code>
* navigates from the last row to the first row in each page.
* The code could also have left the cursor before the first row on each page and then
* used the method <code>next</code> in a <code>while</code> loop to navigate each page
* from the first row to the last row.
* <P>
* The following code fragment assumes a continuation from the previous code fragment,
* meaning that the cursor for the tenth <code>CachedRowSet</code> object is on the
* last row. The code moves the cursor to after the last row so that the first
* call to the method <code>previous</code> will put the cursor back on the last row.
* After going through all of the rows in the last page (the <code>CachedRowSet</code>
* object <i>crs</i>), the code then enters
* the <code>while</code> loop to get to the ninth page, go through the rows backwards,
* go to the eighth page, go through the rows backwards, and so on to the first row
* of the first page.
*
* <PRE>
* crs.afterLast();
* while(crs.previous()) {
* . . . // navigate through the rows, last to first
* {
* while(crs.previousPage()) {
* crs.afterLast();
* while(crs.previous()) {
* . . . // go from the last row to the first row of each page
* }
* }
* </PRE>
*
* @author Jonathan Bruce
*/
public interface CachedRowSet extends RowSet, Joinable {
/**
* Populates this <code>CachedRowSet</code> object with data from
* the given <code>ResultSet</code> object.
* <P>
* This method can be used as an alternative to the <code>execute</code> method when an
* application has a connection to an open <code>ResultSet</code> object.
* Using the method <code>populate</code> can be more efficient than using
* the version of the <code>execute</code> method that takes no parameters
* because it does not open a new connection and re-execute this
* <code>CachedRowSet</code> object's command. Using the <code>populate</code>
* method is more a matter of convenience when compared to using the version
* of <code>execute</code> that takes a <code>ResultSet</code> object.
*
* @param data the <code>ResultSet</code> object containing the data
* to be read into this <code>CachedRowSet</code> object
* @throws SQLException if a null <code>ResultSet</code> object is supplied
* or this <code>CachedRowSet</code> object cannot
* retrieve the associated <code>ResultSetMetaData</code> object
* @see #execute
* @see java.sql.ResultSet
* @see java.sql.ResultSetMetaData
*/
public void populate(ResultSet data) throws SQLException;
/**
* Populates this <code>CachedRowSet</code> object with data, using the
* given connection to produce the result set from which the data will be read.
* This method should close any database connections that it creates to
* ensure that this <code>CachedRowSet</code> object is disconnected except when
* it is reading data from its data source or writing data to its data source.
* <P>
* The reader for this <code>CachedRowSet</code> object
* will use <i>conn</i> to establish a connection to the data source
* so that it can execute the rowset's command and read data from the
* the resulting <code>ResultSet</code> object into this
* <code>CachedRowSet</code> object. This method also closes <i>conn</i>
* after it has populated this <code>CachedRowSet</code> object.
* <P>
* If this method is called when an implementation has already been
* populated, the contents and the metadata are (re)set. Also, if this method is
* called before the method <code>acceptChanges</code> has been called
* to commit outstanding updates, those updates are lost.
*
* @param conn a standard JDBC <code>Connection</code> object with valid
* properties
* @throws SQLException if an invalid <code>Connection</code> object is supplied
* or an error occurs in establishing the connection to the
* data source
* @see #populate
* @see java.sql.Connection
*/
public void execute(Connection conn) throws SQLException;
/**
* Propagates row update, insert and delete changes made to this
* <code>CachedRowSet</code> object to the underlying data source.
* <P>
* This method calls on this <code>CachedRowSet</code> object's writer
* to do the work behind the scenes.
* Standard <code>CachedRowSet</code> implementations should use the
* <code>SyncFactory</code> singleton
* to obtain a <code>SyncProvider</code> instance providing a
* <code>RowSetWriter</code> object (writer). The writer will attempt
* to propagate changes made in this <code>CachedRowSet</code> object
* back to the data source.
* <P>
* When the method <code>acceptChanges</code> executes successfully, in
* addition to writing changes to the data source, it
* makes the values in the current row be the values in the original row.
* <P>
* Depending on the synchronization level of the <code>SyncProvider</code>
* implementation being used, the writer will compare the original values
* with those in the data source to check for conflicts. When there is a conflict,
* the <code>RIOptimisticProvider</code> implementation, for example, throws a
* <code>SyncProviderException</code> and does not write anything to the
* data source.
* <P>
* An application may choose to catch the <code>SyncProviderException</code>
* object and retrieve the <code>SyncResolver</code> object it contains.
* The <code>SyncResolver</code> object lists the conflicts row by row and
* sets a lock on the data source to avoid further conflicts while the
* current conflicts are being resolved.
* Further, for each conflict, it provides methods for examining the conflict
* and setting the value that should be persisted in the data source.
* After all conflicts have been resolved, an application must call the
* <code>acceptChanges</code> method again to write resolved values to the
* data source. If all of the values in the data source are already the
* values to be persisted, the method <code>acceptChanges</code> does nothing.
* <P>
* Some provider implementations may use locks to ensure that there are no
* conflicts. In such cases, it is guaranteed that the writer will succeed in
* writing changes to the data source when the method <code>acceptChanges</code>
* is called. This method may be called immediately after the methods
* <code>updateRow</code>, <code>insertRow</code>, or <code>deleteRow</code>
* have been called, but it is more efficient to call it only once after
* all changes have been made so that only one connection needs to be
* established.
* <P>
* Note: The <code>acceptChanges()</code> method will determine if the
* <code>COMMIT_ON_ACCEPT_CHANGES</code> is set to true or not. If it is set
* to true, all updates in the synchronization are committed to the data
* source. Otherwise, the application <b>must</b> explicity call the
* <code>commit()</code> or <code>rollback()</code> methods as appropriate.
*
* @throws SyncProviderException if the underlying
* synchronization provider's writer fails to write the updates
* back to the data source
* @see #acceptChanges(java.sql.Connection)
* @see javax.sql.RowSetWriter
* @see javax.sql.rowset.spi.SyncFactory
* @see javax.sql.rowset.spi.SyncProvider
* @see javax.sql.rowset.spi.SyncProviderException
* @see javax.sql.rowset.spi.SyncResolver
*/
public void acceptChanges() throws SyncProviderException;
/**
* Propagates all row update, insert and delete changes to the
* data source backing this <code>CachedRowSet</code> object
* using the specified <code>Connection</code> object to establish a
* connection to the data source.
* <P>
* The other version of the <code>acceptChanges</code> method is not passed
* a connection because it uses
* the <code>Connection</code> object already defined within the <code>RowSet</code>
* object, which is the connection used for populating it initially.
* <P>
* This form of the method <code>acceptChanges</code> is similar to the
* form that takes no arguments; however, unlike the other form, this form
* can be used only when the underlying data source is a JDBC data source.
* The updated <code>Connection</code> properties must be used by the
* <code>SyncProvider</code> to reset the <code>RowSetWriter</code>
* configuration to ensure that the contents of the <code>CachedRowSet</code>
* object are synchronized correctly.
* <P>
* When the method <code>acceptChanges</code> executes successfully, in
* addition to writing changes to the data source, it
* makes the values in the current row be the values in the original row.
* <P>
* Depending on the synchronization level of the <code>SyncProvider</code>
* implementation being used, the writer will compare the original values
* with those in the data source to check for conflicts. When there is a conflict,
* the <code>RIOptimisticProvider</code> implementation, for example, throws a
* <code>SyncProviderException</code> and does not write anything to the
* data source.
* <P>
* An application may choose to catch the <code>SyncProviderException</code>
* object and retrieve the <code>SyncResolver</code> object it contains.
* The <code>SyncResolver</code> object lists the conflicts row by row and
* sets a lock on the data source to avoid further conflicts while the
* current conflicts are being resolved.
* Further, for each conflict, it provides methods for examining the conflict
* and setting the value that should be persisted in the data source.
* After all conflicts have been resolved, an application must call the
* <code>acceptChanges</code> method again to write resolved values to the
* data source. If all of the values in the data source are already the
* values to be persisted, the method <code>acceptChanges</code> does nothing.
* <P>
* Some provider implementations may use locks to ensure that there are no
* conflicts. In such cases, it is guaranteed that the writer will succeed in
* writing changes to the data source when the method <code>acceptChanges</code>
* is called. This method may be called immediately after the methods
* <code>updateRow</code>, <code>insertRow</code>, or <code>deleteRow</code>
* have been called, but it is more efficient to call it only once after
* all changes have been made so that only one connection needs to be
* established.
* <P>
* Note: The <code>acceptChanges()</code> method will determine if the
* <code>COMMIT_ON_ACCEPT_CHANGES</code> is set to true or not. If it is set
* to true, all updates in the synchronization are committed to the data
* source. Otherwise, the application <b>must</b> explicity call the
* <code>commit</code> or <code>rollback</code> methods as appropriate.
*
* @param con a standard JDBC <code>Connection</code> object
* @throws SyncProviderException if the underlying
* synchronization provider's writer fails to write the updates
* back to the data source
* @see #acceptChanges()
* @see javax.sql.RowSetWriter
* @see javax.sql.rowset.spi.SyncFactory
* @see javax.sql.rowset.spi.SyncProvider
* @see javax.sql.rowset.spi.SyncProviderException
* @see javax.sql.rowset.spi.SyncResolver
*/
public void acceptChanges(Connection con) throws SyncProviderException;
/**
* Restores this <code>CachedRowSet</code> object to its original
* value, that is, its value before the last set of changes. If there
* have been no changes to the rowset or only one set of changes,
* the original value is the value with which this <code>CachedRowSet</code> object
* was populated; otherwise, the original value is
* the value it had immediately before its current value.
* <P>
* When this method is called, a <code>CachedRowSet</code> implementation
* must ensure that all updates, inserts, and deletes to the current
* rowset instance are replaced by the previous values. In addition,
* the cursor should be
* reset to the first row and a <code>rowSetChanged</code> event
* should be fired to notify all registered listeners.
*
* @throws SQLException if an error occurs rolling back the current value of
* this <code>CachedRowSet</code> object to its previous value
* @see javax.sql.RowSetListener#rowSetChanged
*/
public void restoreOriginal() throws SQLException;
/**
* Releases the current contents of this <code>CachedRowSet</code>
* object and sends a <code>rowSetChanged</code> event to all
* registered listeners. Any outstanding updates are discarded and
* the rowset contains no rows after this method is called. There
* are no interactions with the underlying data source, and any rowset
* content, metadata, and content updates should be non-recoverable.
* <P>
* This <code>CachedRowSet</code> object should lock until its contents and
* associated updates are fully cleared, thus preventing 'dirty' reads by
* other components that hold a reference to this <code>RowSet</code> object.
* In addition, the contents cannot be released
* until all all components reading this <code>CachedRowSet</code> object
* have completed their reads. This <code>CachedRowSet</code> object
* should be returned to normal behavior after firing the
* <code>rowSetChanged</code> event.
* <P>
* The metadata, including JDBC properties and Synchronization SPI
* properties, are maintained for future use. It is important that
* properties such as the <code>command</code> property be
* relevant to the originating data source from which this <code>CachedRowSet</code>
* object was originally established.
* <P>
* This method empties a rowset, as opposed to the <code>close</code> method,
* which marks the entire rowset as recoverable to allow the garbage collector
* the rowset's Java VM resources.
*
* @throws SQLException if an error occurs flushing the contents of this
* <code>CachedRowSet</code> object
* @see javax.sql.RowSetListener#rowSetChanged
* @see java.sql.ResultSet#close
*/
public void release() throws SQLException;
/**
* Cancels the deletion of the current row and notifies listeners that
* a row has changed. After this method is called, the current row is
* no longer marked for deletion. This method can be called at any
* time during the lifetime of the rowset.
* <P>
* In addition, multiple cancellations of row deletions can be made
* by adjusting the position of the cursor using any of the cursor
* position control methods such as:
* <ul>
* <li><code>CachedRowSet.absolute</code>
* <li><code>CachedRowSet.first</code>
* <li><code>CachedRowSet.last</code>
* </ul>
*
* @throws SQLException if (1) the current row has not been deleted or
* (2) the cursor is on the insert row, before the first row, or
* after the last row
* @see javax.sql.rowset.CachedRowSet#undoInsert
* @see java.sql.ResultSet#cancelRowUpdates
*/
public void undoDelete() throws SQLException;
/**
* Immediately removes the current row from this <code>CachedRowSet</code>
* object if the row has been inserted, and also notifies listeners that a
* row has changed. This method can be called at any time during the
* lifetime of a rowset and assuming the current row is within
* the exception limitations (see below), it cancels the row insertion
* of the current row.
* <P>
* In addition, multiple cancellations of row insertions can be made
* by adjusting the position of the cursor using any of the cursor
* position control methods such as:
* <ul>
* <li><code>CachedRowSet.absolute</code>
* <li><code>CachedRowSet.first</code>
* <li><code>CachedRowSet.last</code>
* </ul>
*
* @throws SQLException if (1) the current row has not been inserted or (2)
* the cursor is before the first row, after the last row, or on the
* insert row
* @see javax.sql.rowset.CachedRowSet#undoDelete
* @see java.sql.ResultSet#cancelRowUpdates
*/
public void undoInsert() throws SQLException;
/**
* Immediately reverses the last update operation if the
* row has been modified. This method can be
* called to reverse updates on all columns until all updates in a row have
* been rolled back to their state just prior to the last synchronization
* (<code>acceptChanges</code>) or population. This method may also be called
* while performing updates to the insert row.
* <P>
* <code>undoUpdate</code> may be called at any time during the lifetime of a
* rowset; however, after a synchronization has occurred, this method has no
* effect until further modification to the rowset data has occurred.
*
* @throws SQLException if the cursor is before the first row or after the last
* row in in this <code>CachedRowSet</code> object
* @see #undoDelete
* @see #undoInsert
* @see java.sql.ResultSet#cancelRowUpdates
*/
public void undoUpdate() throws SQLException;
/**
* Indicates whether the designated column in the current row of this
* <code>CachedRowSet</code> object has been updated.
*
* @param idx an <code>int</code> identifying the column to be checked for updates
* @return <code>true</code> if the designated column has been visibly updated;
* <code>false</code> otherwise
* @throws SQLException if the cursor is on the insert row, before the first row,
* or after the last row
* @see java.sql.DatabaseMetaData#updatesAreDetected
*/
public boolean columnUpdated(int idx) throws SQLException;
/**
* Indicates whether the designated column in the current row of this
* <code>CachedRowSet</code> object has been updated.
*
* @param columnName a <code>String</code> object giving the name of the
* column to be checked for updates
* @return <code>true</code> if the column has been visibly updated;
* <code>false</code> otherwise
* @throws SQLException if the cursor is on the insert row, before the first row,
* or after the last row
* @see java.sql.DatabaseMetaData#updatesAreDetected
*/
public boolean columnUpdated(String columnName) throws SQLException;
/**
* Converts this <code>CachedRowSet</code> object to a <code>Collection</code>
* object that contains all of this <code>CachedRowSet</code> object's data.
* Implementations have some latitude in
* how they can represent this <code>Collection</code> object because of the
* abstract nature of the <code>Collection</code> framework.
* Each row must be fully represented in either a
* general purpose <code>Collection</code> implementation or a specialized
* <code>Collection</code> implementation, such as a <code>TreeMap</code>
* object or a <code>Vector</code> object.
* An SQL <code>NULL</code> column value must be represented as a <code>null</code>
* in the Java programming language.
* <P>
* The standard reference implementation for the <code>CachedRowSet</code>
* interface uses a <code>TreeMap</code> object for the rowset, with the
* values in each row being contained in <code>Vector</code> objects. It is
* expected that most implementations will do the same.
* <P>
* The <code>TreeMap</code> type of collection guarantees that the map will be in
* ascending key order, sorted according to the natural order for the
* key's class.
* Each key references a <code>Vector</code> object that corresponds to one
* row of a <code>RowSet</code> object. Therefore, the size of each
* <code>Vector</code> object must be exactly equal to the number of
* columns in the <code>RowSet</code> object.
* The key used by the <code>TreeMap</code> collection is determined by the
* implementation, which may choose to leverage a set key that is
* available within the internal <code>RowSet</code> tabular structure by
* virtue of a key already set either on the <code>RowSet</code> object
* itself or on the underlying SQL data.
* <P>
*
* @return a <code>Collection</code> object that contains the values in
* each row in this <code>CachedRowSet</code> object
* @throws SQLException if an error occurs generating the collection
* @see #toCollection(int)
* @see #toCollection(String)
*/
public Collection<?> toCollection() throws SQLException;
/**
* Converts the designated column in this <code>CachedRowSet</code> object
* to a <code>Collection</code> object. Implementations have some latitude in
* how they can represent this <code>Collection</code> object because of the
* abstract nature of the <code>Collection</code> framework.
* Each column value should be fully represented in either a
* general purpose <code>Collection</code> implementation or a specialized
* <code>Collection</code> implementation, such as a <code>Vector</code> object.
* An SQL <code>NULL</code> column value must be represented as a <code>null</code>
* in the Java programming language.
* <P>
* The standard reference implementation uses a <code>Vector</code> object
* to contain the column values, and it is expected
* that most implementations will do the same. If a <code>Vector</code> object
* is used, it size must be exactly equal to the number of rows
* in this <code>CachedRowSet</code> object.
*
* @param column an <code>int</code> indicating the column whose values
* are to be represented in a <code>Collection</code> object
* @return a <code>Collection</code> object that contains the values
* stored in the specified column of this <code>CachedRowSet</code>
* object
* @throws SQLException if an error occurs generating the collection or
* an invalid column id is provided
* @see #toCollection
* @see #toCollection(String)
*/
public Collection<?> toCollection(int column) throws SQLException;
/**
* Converts the designated column in this <code>CachedRowSet</code> object
* to a <code>Collection</code> object. Implementations have some latitude in
* how they can represent this <code>Collection</code> object because of the
* abstract nature of the <code>Collection</code> framework.
* Each column value should be fully represented in either a
* general purpose <code>Collection</code> implementation or a specialized
* <code>Collection</code> implementation, such as a <code>Vector</code> object.
* An SQL <code>NULL</code> column value must be represented as a <code>null</code>
* in the Java programming language.
* <P>
* The standard reference implementation uses a <code>Vector</code> object
* to contain the column values, and it is expected
* that most implementations will do the same. If a <code>Vector</code> object
* is used, it size must be exactly equal to the number of rows
* in this <code>CachedRowSet</code> object.
*
* @param column a <code>String</code> object giving the name of the
* column whose values are to be represented in a collection
* @return a <code>Collection</code> object that contains the values
* stored in the specified column of this <code>CachedRowSet</code>
* object
* @throws SQLException if an error occurs generating the collection or
* an invalid column id is provided
* @see #toCollection
* @see #toCollection(int)
*/
public Collection<?> toCollection(String column) throws SQLException;
/**
* Retrieves the <code>SyncProvider</code> implementation for this
* <code>CachedRowSet</code> object. Internally, this method is used by a rowset
* to trigger read or write actions between the rowset
* and the data source. For example, a rowset may need to get a handle
* on the the rowset reader (<code>RowSetReader</code> object) from the
* <code>SyncProvider</code> to allow the rowset to be populated.
* <pre>
* RowSetReader rowsetReader = null;
* SyncProvider provider =
* SyncFactory.getInstance("javax.sql.rowset.provider.RIOptimisticProvider");
* if (provider instanceof RIOptimisticProvider) {
* rowsetReader = provider.getRowSetReader();
* }
* </pre>
* Assuming <i>rowsetReader</i> is a private, accessible field within
* the rowset implementation, when an application calls the <code>execute</code>
* method, it in turn calls on the reader's <code>readData</code> method
* to populate the <code>RowSet</code> object.
*<pre>
* rowsetReader.readData((RowSetInternal)this);
* </pre>
* <P>
* In addition, an application can use the <code>SyncProvider</code> object
* returned by this method to call methods that return information about the
* <code>SyncProvider</code> object, including information about the
* vendor, version, provider identification, synchronization grade, and locks
* it currently has set.
*
* @return the <code>SyncProvider</code> object that was set when the rowset
* was instantiated, or if none was was set, the default provider
* @throws SQLException if an error occurs while returning the
* <code>SyncProvider</code> object
* @see #setSyncProvider
*/
public SyncProvider getSyncProvider() throws SQLException;
/**
* Sets the <code>SyncProvider</code> object for this <code>CachedRowSet</code>
* object to the one specified. This method
* allows the <code>SyncProvider</code> object to be reset.
* <P>
* A <code>CachedRowSet</code> implementation should always be instantiated
* with an available <code>SyncProvider</code> mechanism, but there are
* cases where resetting the <code>SyncProvider</code> object is desirable
* or necessary. For example, an application might want to use the default
* <code>SyncProvider</code> object for a time and then choose to use a provider
* that has more recently become available and better fits its needs.
* <P>
* Resetting the <code>SyncProvider</code> object causes the
* <code>RowSet</code> object to request a new <code>SyncProvider</code> implementation
* from the <code>SyncFactory</code>. This has the effect of resetting
* all previous connections and relationships with the originating
* data source and can potentially drastically change the synchronization
* behavior of a disconnected rowset.
*
* @param provider a <code>String</code> object giving the fully qualified class
* name of a <code>SyncProvider</code> implementation
* @throws SQLException if an error occurs while attempting to reset the
* <code>SyncProvider</code> implementation
* @see #getSyncProvider
*/
public void setSyncProvider(String provider) throws SQLException;
/**
* Returns the number of rows in this <code>CachedRowSet</code>
* object.
*
* @return number of rows in the rowset
*/
public int size();
/**
* Sets the metadata for this <code>CachedRowSet</code> object with
* the given <code>RowSetMetaData</code> object. When a
* <code>RowSetReader</code> object is reading the contents of a rowset,
* it creates a <code>RowSetMetaData</code> object and initializes
* it using the methods in the <code>RowSetMetaData</code> implementation.
* The reference implementation uses the <code>RowSetMetaDataImpl</code>
* class. When the reader has completed reading the rowset contents,
* this method is called internally to pass the <code>RowSetMetaData</code>
* object to the rowset.
*
* @param md a <code>RowSetMetaData</code> object containing
* metadata about the columns in this <code>CachedRowSet</code> object
* @throws SQLException if invalid metadata is supplied to the
* rowset
*/
public void setMetaData(RowSetMetaData md) throws SQLException;
/**
* Returns a <code>ResultSet</code> object containing the original value of this
* <code>CachedRowSet</code> object.
* <P>
* The cursor for the <code>ResultSet</code>
* object should be positioned before the first row.
* In addition, the returned <code>ResultSet</code> object should have the following
* properties:
* <UL>
* <LI>ResultSet.TYPE_SCROLL_INSENSITIVE
* <LI>ResultSet.CONCUR_UPDATABLE
* </UL>
* <P>
* The original value for a <code>RowSet</code> object is the value it had before
* the last synchronization with the underlying data source. If there have been
* no synchronizations, the original value will be the value with which the
* <code>RowSet</code> object was populated. This method is called internally
* when an application calls the method <code>acceptChanges</code> and the
* <code>SyncProvider</code> object has been implemented to check for conflicts.
* If this is the case, the writer compares the original value with the value
* currently in the data source to check for conflicts.
*
* @return a <code>ResultSet</code> object that contains the original value for
* this <code>CachedRowSet</code> object
* @throws SQLException if an error occurs producing the
* <code>ResultSet</code> object
*/
public ResultSet getOriginal() throws SQLException;
/**
* Returns a <code>ResultSet</code> object containing the original value for the
* current row only of this <code>CachedRowSet</code> object.
* <P>
* The cursor for the <code>ResultSet</code>
* object should be positioned before the first row.
* In addition, the returned <code>ResultSet</code> object should have the following
* properties:
* <UL>
* <LI>ResultSet.TYPE_SCROLL_INSENSITIVE
* <LI>ResultSet.CONCUR_UPDATABLE
* </UL>
*
* @return the original result set of the row
* @throws SQLException if there is no current row
* @see #setOriginalRow
*/
public ResultSet getOriginalRow() throws SQLException;
/**
* Sets the current row in this <code>CachedRowSet</code> object as the original
* row.
* <P>
* This method is called internally after the any modified values in the current
* row have been synchronized with the data source. The current row must be tagged
* as no longer inserted, deleted or updated.
* <P>
* A call to <code>setOriginalRow</code> is irreversible.
*
* @throws SQLException if there is no current row or an error is
* encountered resetting the contents of the original row
* @see #getOriginalRow
*/
public void setOriginalRow() throws SQLException;
/**
* Returns an identifier for the object (table) that was used to
* create this <code>CachedRowSet</code> object. This name may be set on multiple occasions,
* and the specification imposes no limits on how many times this
* may occur or whether standard implementations should keep track
* of previous table names.
*
* @return a <code>String</code> object giving the name of the table that is the
* source of data for this <code>CachedRowSet</code> object or <code>null</code>
* if no name has been set for the table
* @throws SQLException if an error is encountered returning the table name
* @see javax.sql.RowSetMetaData#getTableName
*/
public String getTableName() throws SQLException;
/**
* Sets the identifier for the table from which this <code>CachedRowSet</code>
* object was derived to the given table name. The writer uses this name to
* determine which table to use when comparing the values in the data source with the
* <code>CachedRowSet</code> object's values during a synchronization attempt.
* The table identifier also indicates where modified values from this
* <code>CachedRowSet</code> object should be written.
* <P>
* The implementation of this <code>CachedRowSet</code> object may obtain the
* the name internally from the <code>RowSetMetaDataImpl</code> object.
*
* @param tabName a <code>String</code> object identifying the table from which this
<code>CachedRowSet</code> object was derived; cannot be <code>null</code>
* but may be an empty string
* @throws SQLException if an error is encountered naming the table or
* <i>tabName</i> is <code>null</code>
* @see javax.sql.RowSetMetaData#setTableName
* @see javax.sql.RowSetWriter
* @see javax.sql.rowset.spi.SyncProvider
*/
public void setTableName(String tabName) throws SQLException;
/**
* Returns an array containing one or more column numbers indicating the columns
* that form a key that uniquely
* identifies a row in this <code>CachedRowSet</code> object.
*
* @return an array containing the column number or numbers that indicate which columns
* constitute a primary key
* for a row in this <code>CachedRowSet</code> object. This array should be
* empty if no columns are representative of a primary key.
* @throws SQLException if this <code>CachedRowSet</code> object is empty
* @see #setKeyColumns
* @see Joinable#getMatchColumnIndexes
* @see Joinable#getMatchColumnNames
*/
public int[] getKeyColumns() throws SQLException;
/**
* Sets this <code>CachedRowSet</code> object's <code>keyCols</code>
* field with the given array of column numbers, which forms a key
* for uniquely identifying a row in this <code>CachedRowSet</code> object.
* <p>
* If a <code>CachedRowSet</code> object becomes part of a <code>JoinRowSet</code>
* object, the keys defined by this method and the resulting constraints are
* maintained if the columns designated as key columns also become match
* columns.
*
* @param keys an array of <code>int</code> indicating the columns that form
* a primary key for this <code>CachedRowSet</code> object; every
* element in the array must be greater than <code>0</code> and
* less than or equal to the number of columns in this rowset
* @throws SQLException if any of the numbers in the given array
* are not valid for this rowset
* @see #getKeyColumns
* @see Joinable#setMatchColumn(String)
* @see Joinable#setMatchColumn(int)
*/
public void setKeyColumns(int[] keys) throws SQLException;
/**
* Returns a new <code>RowSet</code> object backed by the same data as
* that of this <code>CachedRowSet</code> object. In effect, both
* <code>CachedRowSet</code> objects have a cursor over the same data.
* As a result, any changes made by a duplicate are visible to the original
* and to any other duplicates, just as a change made by the original is visible
* to all of its duplicates. If a duplicate calls a method that changes the
* underlying data, the method it calls notifies all registered listeners
* just as it would when it is called by the original <code>CachedRowSet</code>
* object.
* <P>
* In addition, any <code>RowSet</code> object
* created by this method will have the same properties as this
* <code>CachedRowSet</code> object. For example, if this <code>CachedRowSet</code>
* object is read-only, all of its duplicates will also be read-only. If it is
* changed to be updatable, the duplicates also become updatable.
* <P>
* NOTE: If multiple threads access <code>RowSet</code> objects created from
* the <code>createShared()</code> method, the following behavior is specified
* to preserve shared data integrity: reads and writes of all
* shared <code>RowSet</code> objects should be made serially between each
* object and the single underlying tabular structure.
*
* @return a new shared <code>RowSet</code> object that has the same properties
* as this <code>CachedRowSet</code> object and that has a cursor over
* the same data
* @throws SQLException if an error occurs or cloning is not
* supported in the underlying platform
* @see javax.sql.RowSetEvent
* @see javax.sql.RowSetListener
*/
public RowSet createShared() throws SQLException;
/**
* Creates a <code>RowSet</code> object that is a deep copy of the data in
* this <code>CachedRowSet</code> object. In contrast to
* the <code>RowSet</code> object generated from a <code>createShared</code>
* call, updates made to the copy of the original <code>RowSet</code> object
* must not be visible to the original <code>RowSet</code> object. Also, any
* event listeners that are registered with the original
* <code>RowSet</code> must not have scope over the new
* <code>RowSet</code> copies. In addition, any constraint restrictions
* established must be maintained.
*
* @return a new <code>RowSet</code> object that is a deep copy
* of this <code>CachedRowSet</code> object and is
* completely independent of this <code>CachedRowSet</code> object
* @throws SQLException if an error occurs in generating the copy of
* the of this <code>CachedRowSet</code> object
* @see #createShared
* @see #createCopySchema
* @see #createCopyNoConstraints
* @see javax.sql.RowSetEvent
* @see javax.sql.RowSetListener
*/
public CachedRowSet createCopy() throws SQLException;
/**
* Creates a <code>CachedRowSet</code> object that is an empty copy of this
* <code>CachedRowSet</code> object. The copy
* must not contain any contents but only represent the table
* structure of the original <code>CachedRowSet</code> object. In addition, primary
* or foreign key constraints set in the originating <code>CachedRowSet</code> object must
* be equally enforced in the new empty <code>CachedRowSet</code> object.
* In contrast to
* the <code>RowSet</code> object generated from a <code>createShared</code> method
* call, updates made to a copy of this <code>CachedRowSet</code> object with the
* <code>createCopySchema</code> method must not be visible to it.
* <P>
* Applications can form a <code>WebRowSet</code> object from the <code>CachedRowSet</code>
* object returned by this method in order
* to export the <code>RowSet</code> schema definition to XML for future use.
* @return An empty copy of this {@code CachedRowSet} object
* @throws SQLException if an error occurs in cloning the structure of this
* <code>CachedRowSet</code> object
* @see #createShared
* @see #createCopySchema
* @see #createCopyNoConstraints
* @see javax.sql.RowSetEvent
* @see javax.sql.RowSetListener
*/
public CachedRowSet createCopySchema() throws SQLException;
/**
* Creates a <code>CachedRowSet</code> object that is a deep copy of
* this <code>CachedRowSet</code> object's data but is independent of it.
* In contrast to
* the <code>RowSet</code> object generated from a <code>createShared</code>
* method call, updates made to a copy of this <code>CachedRowSet</code> object
* must not be visible to it. Also, any
* event listeners that are registered with this
* <code>CachedRowSet</code> object must not have scope over the new
* <code>RowSet</code> object. In addition, any constraint restrictions
* established for this <code>CachedRowSet</code> object must <b>not</b> be maintained
* in the copy.
*
* @return a new <code>CachedRowSet</code> object that is a deep copy
* of this <code>CachedRowSet</code> object and is
* completely independent of this <code>CachedRowSet</code> object
* @throws SQLException if an error occurs in generating the copy of
* the of this <code>CachedRowSet</code> object
* @see #createCopy
* @see #createShared
* @see #createCopySchema
* @see javax.sql.RowSetEvent
* @see javax.sql.RowSetListener
*/
public CachedRowSet createCopyNoConstraints() throws SQLException;
/**
* Retrieves the first warning reported by calls on this <code>RowSet</code> object.
* Subsequent warnings on this <code>RowSet</code> object will be chained to the
* <code>RowSetWarning</code> object that this method returns.
*
* The warning chain is automatically cleared each time a new row is read.
* This method may not be called on a RowSet object that has been closed;
* doing so will cause a <code>SQLException</code> to be thrown.
*
* @return RowSetWarning the first <code>RowSetWarning</code>
* object reported or null if there are none
* @throws SQLException if this method is called on a closed RowSet
* @see RowSetWarning
*/
public RowSetWarning getRowSetWarnings() throws SQLException;
/**
* Retrieves a <code>boolean</code> indicating whether rows marked
* for deletion appear in the set of current rows. If <code>true</code> is
* returned, deleted rows are visible with the current rows. If
* <code>false</code> is returned, rows are not visible with the set of
* current rows. The default value is <code>false</code>.
* <P>
* Standard rowset implementations may choose to restrict this behavior
* due to security considerations or to better fit certain deployment
* scenarios. This is left as implementation defined and does not
* represent standard behavior.
* <P>
* Note: Allowing deleted rows to remain visible complicates the behavior
* of some standard JDBC <code>RowSet</code> Implementations methods.
* However, most rowset users can simply ignore this extra detail because
* only very specialized applications will likely want to take advantage of
* this feature.
*
* @return <code>true</code> if deleted rows are visible;
* <code>false</code> otherwise
* @throws SQLException if a rowset implementation is unable to
* to determine whether rows marked for deletion are visible
* @see #setShowDeleted
*/
public boolean getShowDeleted() throws SQLException;
/**
* Sets the property <code>showDeleted</code> to the given
* <code>boolean</code> value, which determines whether
/**代码未完, 请加载全部代码(NowJava.com).**/
关注时代Java
关注时代Java