JDK8/Java8源码在线阅读
/*
* Copyright (c) 2000, 2008, 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
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package javax.management.openmbean;
import com.sun.jmx.mbeanserver.GetPropertyAction;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import javax.management.Descriptor;
import javax.management.ImmutableDescriptor;
/**
* The <code>OpenType</code> class is the parent abstract class of all classes which describe the actual <i>open type</i>
* of open data values.
* <p>
* An <i>open type</i> is defined by:
* <ul>
* <li>the fully qualified Java class name of the open data values this type describes;
* note that only a limited set of Java classes is allowed for open data values
* (see {@link #ALLOWED_CLASSNAMES_LIST ALLOWED_CLASSNAMES_LIST}),</li>
* <li>its name,</li>
* <li>its description.</li>
* </ul>
*
* @param <T> the Java type that instances described by this type must
* have. For example, {@link SimpleType#INTEGER} is a {@code
* SimpleType<Integer>} which is a subclass of {@code OpenType<Integer>},
* meaning that an attribute, parameter, or return value that is described
* as a {@code SimpleType.INTEGER} must have Java type
* {@link Integer}.
*
* @since 1.5
*/
public abstract class OpenType<T> implements Serializable {
/* Serial version */
static final long serialVersionUID = -9195195325186646468L;
/**
* List of the fully qualified names of the Java classes allowed for open
* data values. A multidimensional array of any one of these classes or
* their corresponding primitive types is also an allowed class for open
* data values.
*
<pre>ALLOWED_CLASSNAMES_LIST = {
"java.lang.Void",
"java.lang.Boolean",
"java.lang.Character",
"java.lang.Byte",
"java.lang.Short",
"java.lang.Integer",
"java.lang.Long",
"java.lang.Float",
"java.lang.Double",
"java.lang.String",
"java.math.BigDecimal",
"java.math.BigInteger",
"java.util.Date",
"javax.management.ObjectName",
CompositeData.class.getName(),
TabularData.class.getName() } ;
</pre>
*
*/
public static final List<String> ALLOWED_CLASSNAMES_LIST =
Collections.unmodifiableList(
Arrays.asList(
"java.lang.Void",
"java.lang.Boolean",
"java.lang.Character",
"java.lang.Byte",
"java.lang.Short",
"java.lang.Integer",
"java.lang.Long",
"java.lang.Float",
"java.lang.Double",
"java.lang.String",
"java.math.BigDecimal",
"java.math.BigInteger",
"java.util.Date",
"javax.management.ObjectName",
CompositeData.class.getName(), // better refer to these two class names like this, rather than hardcoding a string,
TabularData.class.getName()) ); // in case the package of these classes should change (who knows...)
/**
* @deprecated Use {@link #ALLOWED_CLASSNAMES_LIST ALLOWED_CLASSNAMES_LIST} instead.
*/
@Deprecated
public static final String[] ALLOWED_CLASSNAMES =
ALLOWED_CLASSNAMES_LIST.toArray(new String[0]);
/**
* @serial The fully qualified Java class name of open data values this
* type describes.
*/
private String className;
/**
* @serial The type description (should not be null or empty).
*/
private String description;
/**
* @serial The name given to this type (should not be null or empty).
*/
private String typeName;
/**
* Tells if this type describes an array (checked in constructor).
*/
private transient boolean isArray = false;
/**
* Cached Descriptor for this OpenType, constructed on demand.
*/
private transient Descriptor descriptor;
/* *** Constructor *** */
/**
* Constructs an <code>OpenType</code> instance (actually a subclass instance as <code>OpenType</code> is abstract),
* checking for the validity of the given parameters.
* The validity constraints are described below for each parameter.
* <br>
* @param className The fully qualified Java class name of the open data values this open type describes.
* The valid Java class names allowed for open data values are listed in
* {@link #ALLOWED_CLASSNAMES_LIST ALLOWED_CLASSNAMES_LIST}.
* A multidimensional array of any one of these classes
* or their corresponding primitive types is also an allowed class,
* in which case the class name follows the rules defined by the method
* {@link Class#getName() getName()} of <code>java.lang.Class</code>.
* For example, a 3-dimensional array of Strings has for class name
* "<code>[[[Ljava.lang.String;</code>" (without the quotes).
* <br>
* @param typeName The name given to the open type this instance represents; cannot be a null or empty string.
* <br>
* @param description The human readable description of the open type this instance represents;
* cannot be a null or empty string.
* <br>
* @throws IllegalArgumentException if <var>className</var>, <var>typeName</var> or <var>description</var>
* is a null or empty string
* <br>
* @throws OpenDataException if <var>className</var> is not one of the allowed Java class names for open data
*/
protected OpenType(String className,
String typeName,
String description) throws OpenDataException {
checkClassNameOverride();
this.typeName = valid("typeName", typeName);
this.description = valid("description", description);
this.className = validClassName(className);
this.isArray = (this.className != null && this.className.startsWith("["));
}
/* Package-private constructor for callers we trust to get it right. */
OpenType(String className, String typeName, String description,
boolean isArray) {
this.className = valid("className",className);
this.typeName = valid("typeName", typeName);
this.description = valid("description", description);
this.isArray = isArray;
}
private void checkClassNameOverride() throws SecurityException {
if (this.getClass().getClassLoader() == null)
return; // We trust bootstrap classes.
if (overridesGetClassName(this.getClass())) {
final GetPropertyAction getExtendOpenTypes =
new GetPropertyAction("jmx.extend.open.types");
if (AccessController.doPrivileged(getExtendOpenTypes) == null) {
throw new SecurityException("Cannot override getClassName() " +
"unless -Djmx.extend.open.types");
}
}
}
private static boolean overridesGetClassName(final Class<?> c) {
return AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
public Boolean run() {
try {
return (c.getMethod("getClassName").getDeclaringClass() !=
OpenType.class);
} catch (Exception e) {
return true; // fail safe
}
}
});
}
private static String validClassName(String className) throws OpenDataException {
className = valid("className", className);
// Check if className describes an array class, and determines its elements' class name.
// (eg: a 3-dimensional array of Strings has for class name: "[[[Ljava.lang.String;")
//
int n = 0;
while (className.startsWith("[", n)) {
n++;
}
String eltClassName; // class name of array elements
boolean isPrimitiveArray = false;
if (n > 0) {
if (className.startsWith("L", n) && className.endsWith(";")) {
// removes the n leading '[' + the 'L' characters
// and the last ';' character
eltClassName = className.substring(n+1, className.length()-1);
} else if (n == className.length() - 1) {
// removes the n leading '[' characters
eltClassName = className.substring(n, className.length());
isPrimitiveArray = true;
} else {
throw new OpenDataException("Argument className=\"" + className +
"\" is not a valid class name");
}
} else {
// not an array
eltClassName = className;
}
// Check that eltClassName's value is one of the allowed basic data types for open data
//
boolean ok = false;
if (isPrimitiveArray) {
ok = ArrayType.isPrimitiveContentType(eltClassName);
} else {
ok = ALLOWED_CLASSNAMES_LIST.contains(eltClassName);
}
if ( ! ok ) {
throw new OpenDataException("Argument className=\""+ className +
"\" is not one of the allowed Java class names for open data.");
}
return className;
}
/* Return argValue.trim() provided argValue is neither null nor empty;
otherwise throw IllegalArgumentException. */
private static String valid(String argName, String argValue) {
if (argValue == null || (argValue = argValue.trim()).equals(""))
throw new IllegalArgumentException("Argument " + argName +
" cannot be null or empty");
return argValue;
}
/* Package-private access to a Descriptor containing this OpenType. */
synchronized Descriptor getDescriptor() {
if (descriptor == null) {
descriptor = new ImmutableDescriptor(new String[] {"openType"},
new Object[] {this});
}
return descriptor;
}
/* *** Open type information methods *** */
/**
* Returns the fully qualified Java class name of the open data values
* this open type describes.
* The only possible Java class names for open data values are listed in
* {@link #ALLOWED_CLASSNAMES_LIST ALLOWED_CLASSNAMES_LIST}.
* A multidimensional array of any one of these classes or their
* corresponding primitive types is also an allowed class,
* in which case the class name follows the rules defined by the method
* {@link Class#getName() getName()} of <code>java.lang.Class</code>.
* For example, a 3-dimensional array of Strings has for class name
* "<code>[[[Ljava.lang.String;</code>" (without the quotes),
* a 3-dimensional array of Integers has for class name
* "<code>[[[Ljava.lang.Integer;</code>" (without the quotes),
* and a 3-dimensional array of int has for class name
* "<code>[[[I</code>" (without the quotes)
*
* @return the class name.
*/
public String getClassName() {
return className;
}
// A version of getClassName() that can only be called from within this
// package and that cannot be overridden.
String safeGetClassName() {
return className;
}
/**
* Returns the name of this <code>OpenType</code> instance.
*
* @return the type name.
*/
public String getTypeName() {
return typeName;
}
/**
* Returns the text description of this <code>OpenType</code> instance.
*
* @return the description.
*/
public String getDescription() {
return description;
}
/**
* Returns <code>true</code> if the open data values this open
* type describes are arrays, <code>false</code> otherwise.
*
* @return true if this is an array type.
*/
public boolean isArray() {
return isArray;
}
/**
* Tests whether <var>obj</var> is a value for this open type.
*
* @param obj the object to be tested for validity.
*
* @return <code>true</code> if <var>obj</var> is a value for this
* open type, <code>false</code> otherwise.
*/
public abstract boolean isValue(Object obj) ;
/**
* Tests whether values of the given type can be assigned to this open type.
* The default implementation of this method returns true only if the
* types are equal.
*
* @param ot the type to be tested.
*
* @return true if {@code ot} is assignable to this open type.
*/
boolean isAssignableFrom(OpenType<?> ot) {
return this.equals(ot);
}
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