JDK8/Java8源码在线阅读
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* 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.
*
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package com.sun.rowset.internal;
import java.sql.*;
import javax.sql.*;
import javax.naming.*;
import java.io.*;
import java.lang.reflect.*;
import com.sun.rowset.*;
import javax.sql.rowset.*;
import javax.sql.rowset.spi.*;
/**
* The facility called by the <code>RIOptimisticProvider</code> object
* internally to read data into it. The calling <code>RowSet</code> object
* must have implemented the <code>RowSetInternal</code> interface
* and have the standard <code>CachedRowSetReader</code> object set as its
* reader.
* <P>
* This implementation always reads all rows of the data source,
* and it assumes that the <code>command</code> property for the caller
* is set with a query that is appropriate for execution by a
* <code>PreparedStatement</code> object.
* <P>
* Typically the <code>SyncFactory</code> manages the <code>RowSetReader</code> and
* the <code>RowSetWriter</code> implementations using <code>SyncProvider</code> objects.
* Standard JDBC RowSet implementations provide an object instance of this
* reader by invoking the <code>SyncProvider.getRowSetReader()</code> method.
*
* @author Jonathan Bruce
* @see javax.sql.rowset.spi.SyncProvider
* @see javax.sql.rowset.spi.SyncFactory
* @see javax.sql.rowset.spi.SyncFactoryException
*/
public class CachedRowSetReader implements RowSetReader, Serializable {
/**
* The field that keeps track of whether the writer associated with
* this <code>CachedRowSetReader</code> object's rowset has been called since
* the rowset was populated.
* <P>
* When this <code>CachedRowSetReader</code> object reads data into
* its rowset, it sets the field <code>writerCalls</code> to 0.
* When the writer associated with the rowset is called to write
* data back to the underlying data source, its <code>writeData</code>
* method calls the method <code>CachedRowSetReader.reset</code>,
* which increments <code>writerCalls</code> and returns <code>true</code>
* if <code>writerCalls</code> is 1. Thus, <code>writerCalls</code> equals
* 1 after the first call to <code>writeData</code> that occurs
* after the rowset has had data read into it.
*
* @serial
*/
private int writerCalls = 0;
private boolean userCon = false;
private int startPosition;
private JdbcRowSetResourceBundle resBundle;
public CachedRowSetReader() {
try {
resBundle = JdbcRowSetResourceBundle.getJdbcRowSetResourceBundle();
} catch(IOException ioe) {
throw new RuntimeException(ioe);
}
}
/**
* Reads data from a data source and populates the given
* <code>RowSet</code> object with that data.
* This method is called by the rowset internally when
* the application invokes the method <code>execute</code>
* to read a new set of rows.
* <P>
* After clearing the rowset of its contents, if any, and setting
* the number of writer calls to <code>0</code>, this reader calls
* its <code>connect</code> method to make
* a connection to the rowset's data source. Depending on which
* of the rowset's properties have been set, the <code>connect</code>
* method will use a <code>DataSource</code> object or the
* <code>DriverManager</code> facility to make a connection to the
* data source.
* <P>
* Once the connection to the data source is made, this reader
* executes the query in the calling <code>CachedRowSet</code> object's
* <code>command</code> property. Then it calls the rowset's
* <code>populate</code> method, which reads data from the
* <code>ResultSet</code> object produced by executing the rowset's
* command. The rowset is then populated with this data.
* <P>
* This method's final act is to close the connection it made, thus
* leaving the rowset disconnected from its data source.
*
* @param caller a <code>RowSet</code> object that has implemented
* the <code>RowSetInternal</code> interface and had
* this <code>CachedRowSetReader</code> object set as
* its reader
* @throws SQLException if there is a database access error, there is a
* problem making the connection, or the command property has not
* been set
*/
public void readData(RowSetInternal caller) throws SQLException
{
Connection con = null;
try {
CachedRowSet crs = (CachedRowSet)caller;
// Get rid of the current contents of the rowset.
/**
* Checking added to verify whether page size has been set or not.
* If set then do not close the object as certain parameters need
* to be maintained.
*/
if(crs.getPageSize() == 0 && crs.size() >0 ) {
// When page size is not set,
// crs.size() will show the total no of rows.
crs.close();
}
writerCalls = 0;
// Get a connection. This reader assumes that the necessary
// properties have been set on the caller to let it supply a
// connection.
userCon = false;
con = this.connect(caller);
// Check our assumptions.
if (con == null || crs.getCommand() == null)
throw new SQLException(resBundle.handleGetObject("crsreader.connecterr").toString());
try {
con.setTransactionIsolation(crs.getTransactionIsolation());
} catch (Exception ex) {
;
}
// Use JDBC to read the data.
PreparedStatement pstmt = con.prepareStatement(crs.getCommand());
// Pass any input parameters to JDBC.
decodeParams(caller.getParams(), pstmt);
try {
pstmt.setMaxRows(crs.getMaxRows());
pstmt.setMaxFieldSize(crs.getMaxFieldSize());
pstmt.setEscapeProcessing(crs.getEscapeProcessing());
pstmt.setQueryTimeout(crs.getQueryTimeout());
} catch (Exception ex) {
/*
* drivers may not support the above - esp. older
* drivers being used by the bridge..
*/
throw new SQLException(ex.getMessage());
}
if(crs.getCommand().toLowerCase().indexOf("select") != -1) {
// can be (crs.getCommand()).indexOf("select")) == 0
// because we will be getting resultset when
// it may be the case that some false select query with
// select coming in between instead of first.
// if ((crs.getCommand()).indexOf("?")) does not return -1
// implies a Prepared Statement like query exists.
ResultSet rs = pstmt.executeQuery();
if(crs.getPageSize() == 0){
crs.populate(rs);
}
else {
/**
* If page size has been set then create a ResultSet object that is scrollable using a
* PreparedStatement handle.Also call the populate(ResultSet,int) function to populate
* a page of data as specified by the page size.
*/
pstmt = con.prepareStatement(crs.getCommand(),ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE);
decodeParams(caller.getParams(), pstmt);
try {
pstmt.setMaxRows(crs.getMaxRows());
pstmt.setMaxFieldSize(crs.getMaxFieldSize());
pstmt.setEscapeProcessing(crs.getEscapeProcessing());
pstmt.setQueryTimeout(crs.getQueryTimeout());
} catch (Exception ex) {
/*
* drivers may not support the above - esp. older
* drivers being used by the bridge..
*/
throw new SQLException(ex.getMessage());
}
rs = pstmt.executeQuery();
crs.populate(rs,startPosition);
}
rs.close();
} else {
pstmt.executeUpdate();
}
// Get the data.
pstmt.close();
try {
con.commit();
} catch (SQLException ex) {
;
}
// only close connections we created...
if (getCloseConnection() == true)
con.close();
}
catch (SQLException ex) {
// Throw an exception if reading fails for any reason.
throw ex;
} finally {
try {
// only close connections we created...
if (con != null && getCloseConnection() == true) {
try {
if (!con.getAutoCommit()) {
con.rollback();
}
} catch (Exception dummy) {
/*
* not an error condition, we're closing anyway, but
* we'd like to clean up any locks if we can since
* it is not clear the connection pool will clean
* these connections in a timely manner
*/
}
con.close();
con = null;
}
} catch (SQLException e) {
// will get exception if something already went wrong, but don't
// override that exception with this one
}
}
}
/**
* Checks to see if the writer associated with this reader needs
* to reset its state. The writer will need to initialize its state
* if new contents have been read since the writer was last called.
* This method is called by the writer that was registered with
* this reader when components were being wired together.
*
* @return <code>true</code> if writer associated with this reader needs
* to reset the values of its fields; <code>false</code> otherwise
* @throws SQLException if an access error occurs
*/
public boolean reset() throws SQLException {
writerCalls++;
return writerCalls == 1;
}
/**
* Establishes a connection with the data source for the given
* <code>RowSet</code> object. If the rowset's <code>dataSourceName</code>
* property has been set, this method uses the JNDI API to retrieve the
* <code>DataSource</code> object that it can use to make the connection.
* If the url, username, and password properties have been set, this
* method uses the <code>DriverManager.getConnection</code> method to
* make the connection.
* <P>
* This method is used internally by the reader and writer associated with
* the calling <code>RowSet</code> object; an application never calls it
* directly.
*
* @param caller a <code>RowSet</code> object that has implemented
* the <code>RowSetInternal</code> interface and had
* this <code>CachedRowSetReader</code> object set as
* its reader
* @return a <code>Connection</code> object that represents a connection
* to the caller's data source
* @throws SQLException if an access error occurs
*/
public Connection connect(RowSetInternal caller) throws SQLException {
// Get a JDBC connection.
if (caller.getConnection() != null) {
// A connection was passed to execute(), so use it.
// As we are using a connection the user gave us we
// won't close it.
userCon = true;
return caller.getConnection();
}
else if (((RowSet)caller).getDataSourceName() != null) {
// Connect using JNDI.
try {
Context ctx = new InitialContext();
DataSource ds = (DataSource)ctx.lookup
(((RowSet)caller).getDataSourceName());
// Check for username, password,
// if it exists try getting a Connection handle through them
// else try without these
// else throw SQLException
if(((RowSet)caller).getUsername() != null) {
return ds.getConnection(((RowSet)caller).getUsername(),
((RowSet)caller).getPassword());
} else {
return ds.getConnection();
}
}
catch (javax.naming.NamingException ex) {
SQLException sqlEx = new SQLException(resBundle.handleGetObject("crsreader.connect").toString());
sqlEx.initCause(ex);
throw sqlEx;
}
} else if (((RowSet)caller).getUrl() != null) {
// Connect using the driver manager.
return DriverManager.getConnection(((RowSet)caller).getUrl(),
((RowSet)caller).getUsername(),
((RowSet)caller).getPassword());
}
else {
return null;
}
}
/**
* Sets the parameter placeholders
* in the rowset's command (the given <code>PreparedStatement</code>
* object) with the parameters in the given array.
* This method, called internally by the method
* <code>CachedRowSetReader.readData</code>, reads each parameter, and
* based on its type, determines the correct
* <code>PreparedStatement.setXXX</code> method to use for setting
* that parameter.
*
* @param params an array of parameters to be used with the given
* <code>PreparedStatement</code> object
* @param pstmt the <code>PreparedStatement</code> object that is the
* command for the calling rowset and into which
* the given parameters are to be set
* @throws SQLException if an access error occurs
*/
@SuppressWarnings("deprecation")
private void decodeParams(Object[] params,
PreparedStatement pstmt) throws SQLException {
// There is a corresponding decodeParams in JdbcRowSetImpl
// which does the same as this method. This is a design flaw.
// Update the JdbcRowSetImpl.decodeParams when you update
// this method.
// Adding the same comments to JdbcRowSetImpl.decodeParams.
int arraySize;
Object[] param = null;
for (int i=0; i < params.length; i++) {
if (params[i] instanceof Object[]) {
param = (Object[])params[i];
if (param.length == 2) {
if (param[0] == null) {
pstmt.setNull(i + 1, ((Integer)param[1]).intValue());
continue;
}
if (param[0] instanceof java.sql.Date ||
param[0] instanceof java.sql.Time ||
param[0] instanceof java.sql.Timestamp) {
System.err.println(resBundle.handleGetObject("crsreader.datedetected").toString());
if (param[1] instanceof java.util.Calendar) {
System.err.println(resBundle.handleGetObject("crsreader.caldetected").toString());
pstmt.setDate(i + 1, (java.sql.Date)param[0],
(java.util.Calendar)param[1]);
continue;
}
else {
throw new SQLException(resBundle.handleGetObject("crsreader.paramtype").toString());
}
}
if (param[0] instanceof Reader) {
pstmt.setCharacterStream(i + 1, (Reader)param[0],
((Integer)param[1]).intValue());
continue;
}
/*
* What's left should be setObject(int, Object, scale)
*/
if (param[1] instanceof Integer) {
pstmt.setObject(i + 1, param[0], ((Integer)param[1]).intValue());
continue;
}
} else if (param.length == 3) {
if (param[0] == null) {
pstmt.setNull(i + 1, ((Integer)param[1]).intValue(),
(String)param[2]);
continue;
}
if (param[0] instanceof java.io.InputStream) {
switch (((Integer)param[2]).intValue()) {
case CachedRowSetImpl.UNICODE_STREAM_PARAM:
pstmt.setUnicodeStream(i + 1,
(java.io.InputStream)param[0],
((Integer)param[1]).intValue());
break;
case CachedRowSetImpl.BINARY_STREAM_PARAM:
pstmt.setBinaryStream(i + 1,
(java.io.InputStream)param[0],
((Integer)param[1]).intValue());
break;
case CachedRowSetImpl.ASCII_STREAM_PARAM:
pstmt.setAsciiStream(i + 1,
(java.io.InputStream)param[0],
((Integer)param[1]).intValue());
break;
default:
throw new SQLException(resBundle.handleGetObject("crsreader.paramtype").toString());
}
}
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