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722 lines
27 KiB
722 lines
27 KiB
/*
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* Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package javax.management;
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import java.io.IOException;
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import java.io.StreamCorruptedException;
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import java.io.Serializable;
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import java.io.ObjectOutputStream;
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import java.io.ObjectInputStream;
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import java.lang.reflect.Method;
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import java.util.Arrays;
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import java.util.Map;
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import java.util.WeakHashMap;
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import java.security.AccessController;
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import java.security.PrivilegedAction;
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import java.util.Objects;
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import static javax.management.ImmutableDescriptor.nonNullDescriptor;
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/**
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* <p>Describes the management interface exposed by an MBean; that is,
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* the set of attributes and operations which are available for
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* management operations. Instances of this class are immutable.
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* Subclasses may be mutable but this is not recommended.</p>
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*
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* <p id="info-changed">Usually the {@code MBeanInfo} for any given MBean does
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* not change over the lifetime of that MBean. Dynamic MBeans can change their
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* {@code MBeanInfo} and in that case it is recommended that they emit a {@link
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* Notification} with a {@linkplain Notification#getType() type} of {@code
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* "jmx.mbean.info.changed"} and a {@linkplain Notification#getUserData()
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* userData} that is the new {@code MBeanInfo}. This is not required, but
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* provides a conventional way for clients of the MBean to discover the change.
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* See also the <a href="Descriptor.html#immutableInfo">immutableInfo</a> and
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* <a href="Descriptor.html#infoTimeout">infoTimeout</a> fields in the {@code
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* MBeanInfo} {@link Descriptor}.</p>
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*
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* <p>The contents of the <code>MBeanInfo</code> for a Dynamic MBean
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* are determined by its {@link DynamicMBean#getMBeanInfo
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* getMBeanInfo()} method. This includes Open MBeans and Model
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* MBeans, which are kinds of Dynamic MBeans.</p>
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*
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* <p>The contents of the <code>MBeanInfo</code> for a Standard MBean
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* are determined by the MBean server as follows:</p>
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*
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* <ul>
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*
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* <li>{@link #getClassName()} returns the Java class name of the MBean
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* object;
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*
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* <li>{@link #getConstructors()} returns the list of all public
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* constructors in that object;
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*
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* <li>{@link #getAttributes()} returns the list of all attributes
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* whose existence is deduced from the presence in the MBean interface
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* of a <code>get<i>Name</i></code>, <code>is<i>Name</i></code>, or
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* <code>set<i>Name</i></code> method that conforms to the conventions
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* for Standard MBeans;
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*
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* <li>{@link #getOperations()} returns the list of all methods in
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* the MBean interface that do not represent attributes;
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*
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* <li>{@link #getNotifications()} returns an empty array if the MBean
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* does not implement the {@link NotificationBroadcaster} interface,
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* otherwise the result of calling {@link
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* NotificationBroadcaster#getNotificationInfo()} on it;
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*
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* <li>{@link #getDescriptor()} returns a descriptor containing the contents
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* of any descriptor annotations in the MBean interface (see
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* {@link DescriptorKey @DescriptorKey}).
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*
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* </ul>
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*
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* <p>The description returned by {@link #getDescription()} and the
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* descriptions of the contained attributes and operations are not specified.</p>
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*
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* <p>The remaining details of the <code>MBeanInfo</code> for a
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* Standard MBean are not specified. This includes the description of
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* any contained constructors, and notifications; the names
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* of parameters to constructors and operations; and the descriptions of
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* constructor parameters.</p>
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*
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* @since 1.5
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*/
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public class MBeanInfo implements Cloneable, Serializable, DescriptorRead {
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/* Serial version */
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static final long serialVersionUID = -6451021435135161911L;
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/**
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* @serial The Descriptor for the MBean. This field
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* can be null, which is equivalent to an empty Descriptor.
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*/
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private transient Descriptor descriptor;
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/**
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* @serial The human readable description of the class.
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*/
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private final String description;
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/**
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* @serial The MBean qualified name.
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*/
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private final String className;
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/**
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* @serial The MBean attribute descriptors.
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*/
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private final MBeanAttributeInfo[] attributes;
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/**
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* @serial The MBean operation descriptors.
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*/
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private final MBeanOperationInfo[] operations;
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/**
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* @serial The MBean constructor descriptors.
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*/
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private final MBeanConstructorInfo[] constructors;
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/**
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* @serial The MBean notification descriptors.
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*/
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private final MBeanNotificationInfo[] notifications;
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private transient int hashCode;
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/**
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* <p>True if this class is known not to override the array-valued
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* getters of MBeanInfo. Obviously true for MBeanInfo itself, and true
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* for a subclass where we succeed in reflecting on the methods
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* and discover they are not overridden.</p>
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*
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* <p>The purpose of this variable is to avoid cloning the arrays
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* when doing operations like {@link #equals} where we know they
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* will not be changed. If a subclass overrides a getter, we
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* cannot access the corresponding array directly.</p>
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*/
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private final transient boolean arrayGettersSafe;
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/**
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* Constructs an <CODE>MBeanInfo</CODE>.
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*
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* @param className The name of the Java class of the MBean described
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* by this <CODE>MBeanInfo</CODE>. This value may be any
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* syntactically legal Java class name. It does not have to be a
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* Java class known to the MBean server or to the MBean's
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* ClassLoader. If it is a Java class known to the MBean's
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* ClassLoader, it is recommended but not required that the
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* class's public methods include those that would appear in a
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* Standard MBean implementing the attributes and operations in
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* this MBeanInfo.
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* @param description A human readable description of the MBean (optional).
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* @param attributes The list of exposed attributes of the MBean.
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* This may be null with the same effect as a zero-length array.
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* @param constructors The list of public constructors of the
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* MBean. This may be null with the same effect as a zero-length
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* array.
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* @param operations The list of operations of the MBean. This
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* may be null with the same effect as a zero-length array.
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* @param notifications The list of notifications emitted. This
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* may be null with the same effect as a zero-length array.
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*/
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public MBeanInfo(String className,
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String description,
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MBeanAttributeInfo[] attributes,
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MBeanConstructorInfo[] constructors,
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MBeanOperationInfo[] operations,
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MBeanNotificationInfo[] notifications)
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throws IllegalArgumentException {
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this(className, description, attributes, constructors, operations,
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notifications, null);
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}
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/**
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* Constructs an <CODE>MBeanInfo</CODE>.
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*
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* @param className The name of the Java class of the MBean described
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* by this <CODE>MBeanInfo</CODE>. This value may be any
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* syntactically legal Java class name. It does not have to be a
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* Java class known to the MBean server or to the MBean's
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* ClassLoader. If it is a Java class known to the MBean's
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* ClassLoader, it is recommended but not required that the
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* class's public methods include those that would appear in a
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* Standard MBean implementing the attributes and operations in
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* this MBeanInfo.
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* @param description A human readable description of the MBean (optional).
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* @param attributes The list of exposed attributes of the MBean.
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* This may be null with the same effect as a zero-length array.
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* @param constructors The list of public constructors of the
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* MBean. This may be null with the same effect as a zero-length
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* array.
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* @param operations The list of operations of the MBean. This
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* may be null with the same effect as a zero-length array.
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* @param notifications The list of notifications emitted. This
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* may be null with the same effect as a zero-length array.
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* @param descriptor The descriptor for the MBean. This may be null
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* which is equivalent to an empty descriptor.
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*
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* @since 1.6
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*/
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public MBeanInfo(String className,
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String description,
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MBeanAttributeInfo[] attributes,
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MBeanConstructorInfo[] constructors,
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MBeanOperationInfo[] operations,
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MBeanNotificationInfo[] notifications,
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Descriptor descriptor)
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throws IllegalArgumentException {
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this.className = className;
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this.description = description;
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if (attributes == null)
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attributes = MBeanAttributeInfo.NO_ATTRIBUTES;
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this.attributes = attributes;
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if (operations == null)
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operations = MBeanOperationInfo.NO_OPERATIONS;
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this.operations = operations;
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if (constructors == null)
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constructors = MBeanConstructorInfo.NO_CONSTRUCTORS;
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this.constructors = constructors;
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if (notifications == null)
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notifications = MBeanNotificationInfo.NO_NOTIFICATIONS;
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this.notifications = notifications;
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if (descriptor == null)
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descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR;
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this.descriptor = descriptor;
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this.arrayGettersSafe =
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arrayGettersSafe(this.getClass(), MBeanInfo.class);
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}
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/**
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* <p>Returns a shallow clone of this instance.
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* The clone is obtained by simply calling <tt>super.clone()</tt>,
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* thus calling the default native shallow cloning mechanism
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* implemented by <tt>Object.clone()</tt>.
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* No deeper cloning of any internal field is made.</p>
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*
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* <p>Since this class is immutable, the clone method is chiefly of
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* interest to subclasses.</p>
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*/
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@Override
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public Object clone () {
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try {
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return super.clone() ;
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} catch (CloneNotSupportedException e) {
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// should not happen as this class is cloneable
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return null;
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}
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}
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/**
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* Returns the name of the Java class of the MBean described by
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* this <CODE>MBeanInfo</CODE>.
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*
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* @return the class name.
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*/
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public String getClassName() {
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return className;
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}
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/**
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* Returns a human readable description of the MBean.
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*
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* @return the description.
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*/
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public String getDescription() {
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return description;
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}
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/**
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* Returns the list of attributes exposed for management.
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* Each attribute is described by an <CODE>MBeanAttributeInfo</CODE> object.
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*
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* The returned array is a shallow copy of the internal array,
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* which means that it is a copy of the internal array of
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* references to the <CODE>MBeanAttributeInfo</CODE> objects
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* but that each referenced <CODE>MBeanAttributeInfo</CODE> object is not copied.
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*
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* @return An array of <CODE>MBeanAttributeInfo</CODE> objects.
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*/
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public MBeanAttributeInfo[] getAttributes() {
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MBeanAttributeInfo[] as = nonNullAttributes();
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if (as.length == 0)
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return as;
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else
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return as.clone();
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}
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private MBeanAttributeInfo[] fastGetAttributes() {
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if (arrayGettersSafe)
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return nonNullAttributes();
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else
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return getAttributes();
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}
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/**
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* Return the value of the attributes field, or an empty array if
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* the field is null. This can't happen with a
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* normally-constructed instance of this class, but can if the
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* instance was deserialized from another implementation that
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* allows the field to be null. It would be simpler if we enforced
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* the class invariant that these fields cannot be null by writing
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* a readObject() method, but that would require us to define the
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* various array fields as non-final, which is annoying because
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* conceptually they are indeed final.
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*/
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private MBeanAttributeInfo[] nonNullAttributes() {
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return (attributes == null) ?
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MBeanAttributeInfo.NO_ATTRIBUTES : attributes;
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}
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/**
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* Returns the list of operations of the MBean.
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* Each operation is described by an <CODE>MBeanOperationInfo</CODE> object.
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*
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* The returned array is a shallow copy of the internal array,
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* which means that it is a copy of the internal array of
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* references to the <CODE>MBeanOperationInfo</CODE> objects
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* but that each referenced <CODE>MBeanOperationInfo</CODE> object is not copied.
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*
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* @return An array of <CODE>MBeanOperationInfo</CODE> objects.
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*/
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public MBeanOperationInfo[] getOperations() {
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MBeanOperationInfo[] os = nonNullOperations();
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if (os.length == 0)
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return os;
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else
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return os.clone();
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}
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private MBeanOperationInfo[] fastGetOperations() {
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if (arrayGettersSafe)
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return nonNullOperations();
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else
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return getOperations();
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}
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private MBeanOperationInfo[] nonNullOperations() {
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return (operations == null) ?
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MBeanOperationInfo.NO_OPERATIONS : operations;
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}
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/**
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* <p>Returns the list of the public constructors of the MBean.
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* Each constructor is described by an
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* <CODE>MBeanConstructorInfo</CODE> object.</p>
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*
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* <p>The returned array is a shallow copy of the internal array,
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* which means that it is a copy of the internal array of
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* references to the <CODE>MBeanConstructorInfo</CODE> objects but
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* that each referenced <CODE>MBeanConstructorInfo</CODE> object
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* is not copied.</p>
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*
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* <p>The returned list is not necessarily exhaustive. That is,
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* the MBean may have a public constructor that is not in the
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* list. In this case, the MBean server can construct another
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* instance of this MBean's class using that constructor, even
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* though it is not listed here.</p>
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*
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* @return An array of <CODE>MBeanConstructorInfo</CODE> objects.
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*/
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public MBeanConstructorInfo[] getConstructors() {
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MBeanConstructorInfo[] cs = nonNullConstructors();
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if (cs.length == 0)
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return cs;
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else
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return cs.clone();
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}
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private MBeanConstructorInfo[] fastGetConstructors() {
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if (arrayGettersSafe)
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return nonNullConstructors();
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else
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return getConstructors();
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}
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private MBeanConstructorInfo[] nonNullConstructors() {
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return (constructors == null) ?
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MBeanConstructorInfo.NO_CONSTRUCTORS : constructors;
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}
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/**
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* Returns the list of the notifications emitted by the MBean.
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* Each notification is described by an <CODE>MBeanNotificationInfo</CODE> object.
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*
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* The returned array is a shallow copy of the internal array,
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* which means that it is a copy of the internal array of
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* references to the <CODE>MBeanNotificationInfo</CODE> objects
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* but that each referenced <CODE>MBeanNotificationInfo</CODE> object is not copied.
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*
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* @return An array of <CODE>MBeanNotificationInfo</CODE> objects.
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*/
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public MBeanNotificationInfo[] getNotifications() {
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MBeanNotificationInfo[] ns = nonNullNotifications();
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if (ns.length == 0)
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return ns;
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else
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return ns.clone();
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}
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private MBeanNotificationInfo[] fastGetNotifications() {
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if (arrayGettersSafe)
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return nonNullNotifications();
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else
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return getNotifications();
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}
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private MBeanNotificationInfo[] nonNullNotifications() {
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return (notifications == null) ?
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MBeanNotificationInfo.NO_NOTIFICATIONS : notifications;
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}
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/**
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* Get the descriptor of this MBeanInfo. Changing the returned value
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* will have no affect on the original descriptor.
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*
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* @return a descriptor that is either immutable or a copy of the original.
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*
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* @since 1.6
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*/
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public Descriptor getDescriptor() {
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return (Descriptor) nonNullDescriptor(descriptor).clone();
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}
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@Override
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public String toString() {
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return
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getClass().getName() + "[" +
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"description=" + getDescription() + ", " +
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"attributes=" + Arrays.asList(fastGetAttributes()) + ", " +
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"constructors=" + Arrays.asList(fastGetConstructors()) + ", " +
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"operations=" + Arrays.asList(fastGetOperations()) + ", " +
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"notifications=" + Arrays.asList(fastGetNotifications()) + ", " +
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"descriptor=" + getDescriptor() +
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"]";
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}
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/**
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* <p>Compare this MBeanInfo to another. Two MBeanInfo objects
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* are equal if and only if they return equal values for {@link
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* #getClassName()}, for {@link #getDescription()}, and for
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* {@link #getDescriptor()}, and the
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* arrays returned by the two objects for {@link
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* #getAttributes()}, {@link #getOperations()}, {@link
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* #getConstructors()}, and {@link #getNotifications()} are
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* pairwise equal. Here "equal" means {@link
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* Object#equals(Object)}, not identity.</p>
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*
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* <p>If two MBeanInfo objects return the same values in one of
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* their arrays but in a different order then they are not equal.</p>
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*
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* @param o the object to compare to.
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*
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* @return true if and only if <code>o</code> is an MBeanInfo that is equal
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* to this one according to the rules above.
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*/
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@Override
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public boolean equals(Object o) {
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if (o == this)
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return true;
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if (!(o instanceof MBeanInfo))
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return false;
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MBeanInfo p = (MBeanInfo) o;
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if (!isEqual(getClassName(), p.getClassName()) ||
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!isEqual(getDescription(), p.getDescription()) ||
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!getDescriptor().equals(p.getDescriptor())) {
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return false;
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}
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return
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(Arrays.equals(p.fastGetAttributes(), fastGetAttributes()) &&
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Arrays.equals(p.fastGetOperations(), fastGetOperations()) &&
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Arrays.equals(p.fastGetConstructors(), fastGetConstructors()) &&
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Arrays.equals(p.fastGetNotifications(), fastGetNotifications()));
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}
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@Override
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public int hashCode() {
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/* Since computing the hashCode is quite expensive, we cache it.
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If by some terrible misfortune the computed value is 0, the
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caching won't work and we will recompute it every time.
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We don't bother synchronizing, because, at worst, n different
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threads will compute the same hashCode at the same time. */
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if (hashCode != 0)
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return hashCode;
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hashCode = Objects.hash(getClassName(), getDescriptor())
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^ Arrays.hashCode(fastGetAttributes())
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^ Arrays.hashCode(fastGetOperations())
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^ Arrays.hashCode(fastGetConstructors())
|
|
^ Arrays.hashCode(fastGetNotifications());
|
|
|
|
return hashCode;
|
|
}
|
|
|
|
/**
|
|
* Cached results of previous calls to arrayGettersSafe. This is
|
|
* a WeakHashMap so that we don't prevent a class from being
|
|
* garbage collected just because we know whether it's immutable.
|
|
*/
|
|
private static final Map<Class<?>, Boolean> arrayGettersSafeMap =
|
|
new WeakHashMap<Class<?>, Boolean>();
|
|
|
|
/**
|
|
* Return true if <code>subclass</code> is known to preserve the
|
|
* immutability of <code>immutableClass</code>. The class
|
|
* <code>immutableClass</code> is a reference class that is known
|
|
* to be immutable. The subclass <code>subclass</code> is
|
|
* considered immutable if it does not override any public method
|
|
* of <code>immutableClass</code> whose name begins with "get".
|
|
* This is obviously not an infallible test for immutability,
|
|
* but it works for the public interfaces of the MBean*Info classes.
|
|
*/
|
|
static boolean arrayGettersSafe(Class<?> subclass, Class<?> immutableClass) {
|
|
if (subclass == immutableClass)
|
|
return true;
|
|
synchronized (arrayGettersSafeMap) {
|
|
Boolean safe = arrayGettersSafeMap.get(subclass);
|
|
if (safe == null) {
|
|
try {
|
|
ArrayGettersSafeAction action =
|
|
new ArrayGettersSafeAction(subclass, immutableClass);
|
|
safe = AccessController.doPrivileged(action);
|
|
} catch (Exception e) { // e.g. SecurityException
|
|
/* We don't know, so we assume it isn't. */
|
|
safe = false;
|
|
}
|
|
arrayGettersSafeMap.put(subclass, safe);
|
|
}
|
|
return safe;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* The PrivilegedAction stuff is probably overkill. We can be
|
|
* pretty sure the caller does have the required privileges -- a
|
|
* JMX user that can't do reflection can't even use Standard
|
|
* MBeans! But there's probably a performance gain by not having
|
|
* to check the whole call stack.
|
|
*/
|
|
private static class ArrayGettersSafeAction
|
|
implements PrivilegedAction<Boolean> {
|
|
|
|
private final Class<?> subclass;
|
|
private final Class<?> immutableClass;
|
|
|
|
ArrayGettersSafeAction(Class<?> subclass, Class<?> immutableClass) {
|
|
this.subclass = subclass;
|
|
this.immutableClass = immutableClass;
|
|
}
|
|
|
|
public Boolean run() {
|
|
Method[] methods = immutableClass.getMethods();
|
|
for (int i = 0; i < methods.length; i++) {
|
|
Method method = methods[i];
|
|
String methodName = method.getName();
|
|
if (methodName.startsWith("get") &&
|
|
method.getParameterTypes().length == 0 &&
|
|
method.getReturnType().isArray()) {
|
|
try {
|
|
Method submethod =
|
|
subclass.getMethod(methodName);
|
|
if (!submethod.equals(method))
|
|
return false;
|
|
} catch (NoSuchMethodException e) {
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
}
|
|
|
|
private static boolean isEqual(String s1, String s2) {
|
|
boolean ret;
|
|
|
|
if (s1 == null) {
|
|
ret = (s2 == null);
|
|
} else {
|
|
ret = s1.equals(s2);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* Serializes an {@link MBeanInfo} to an {@link ObjectOutputStream}.
|
|
* @serialData
|
|
* For compatibility reasons, an object of this class is serialized as follows.
|
|
* <p>
|
|
* The method {@link ObjectOutputStream#defaultWriteObject defaultWriteObject()}
|
|
* is called first to serialize the object except the field {@code descriptor}
|
|
* which is declared as transient. The field {@code descriptor} is serialized
|
|
* as follows:
|
|
* <ul>
|
|
* <li> If {@code descriptor} is an instance of the class
|
|
* {@link ImmutableDescriptor}, the method {@link ObjectOutputStream#write
|
|
* write(int val)} is called to write a byte with the value {@code 1},
|
|
* then the method {@link ObjectOutputStream#writeObject writeObject(Object obj)}
|
|
* is called twice to serialize the field names and the field values of the
|
|
* {@code descriptor}, respectively as a {@code String[]} and an
|
|
* {@code Object[]};</li>
|
|
* <li> Otherwise, the method {@link ObjectOutputStream#write write(int val)}
|
|
* is called to write a byte with the value {@code 0}, then the method
|
|
* {@link ObjectOutputStream#writeObject writeObject(Object obj)} is called
|
|
* to serialize the field {@code descriptor} directly.
|
|
* </ul>
|
|
*
|
|
* @since 1.6
|
|
*/
|
|
private void writeObject(ObjectOutputStream out) throws IOException {
|
|
out.defaultWriteObject();
|
|
|
|
if (descriptor.getClass() == ImmutableDescriptor.class) {
|
|
out.write(1);
|
|
|
|
final String[] names = descriptor.getFieldNames();
|
|
|
|
out.writeObject(names);
|
|
out.writeObject(descriptor.getFieldValues(names));
|
|
} else {
|
|
out.write(0);
|
|
|
|
out.writeObject(descriptor);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Deserializes an {@link MBeanInfo} from an {@link ObjectInputStream}.
|
|
* @serialData
|
|
* For compatibility reasons, an object of this class is deserialized as follows.
|
|
* <p>
|
|
* The method {@link ObjectInputStream#defaultReadObject defaultReadObject()}
|
|
* is called first to deserialize the object except the field
|
|
* {@code descriptor}, which is not serialized in the default way. Then the method
|
|
* {@link ObjectInputStream#read read()} is called to read a byte, the field
|
|
* {@code descriptor} is deserialized according to the value of the byte value:
|
|
* <ul>
|
|
* <li>1. The method {@link ObjectInputStream#readObject readObject()}
|
|
* is called twice to obtain the field names (a {@code String[]}) and
|
|
* the field values (a {@code Object[]}) of the {@code descriptor}.
|
|
* The two obtained values then are used to construct
|
|
* an {@link ImmutableDescriptor} instance for the field
|
|
* {@code descriptor};</li>
|
|
* <li>0. The value for the field {@code descriptor} is obtained directly
|
|
* by calling the method {@link ObjectInputStream#readObject readObject()}.
|
|
* If the obtained value is null, the field {@code descriptor} is set to
|
|
* {@link ImmutableDescriptor#EMPTY_DESCRIPTOR EMPTY_DESCRIPTOR};</li>
|
|
* <li>-1. This means that there is no byte to read and that the object is from
|
|
* an earlier version of the JMX API. The field {@code descriptor} is set to
|
|
* {@link ImmutableDescriptor#EMPTY_DESCRIPTOR EMPTY_DESCRIPTOR}.</li>
|
|
* <li>Any other value. A {@link StreamCorruptedException} is thrown.</li>
|
|
* </ul>
|
|
*
|
|
* @since 1.6
|
|
*/
|
|
|
|
private void readObject(ObjectInputStream in)
|
|
throws IOException, ClassNotFoundException {
|
|
|
|
in.defaultReadObject();
|
|
|
|
switch (in.read()) {
|
|
case 1:
|
|
final String[] names = (String[])in.readObject();
|
|
|
|
final Object[] values = (Object[]) in.readObject();
|
|
descriptor = (names.length == 0) ?
|
|
ImmutableDescriptor.EMPTY_DESCRIPTOR :
|
|
new ImmutableDescriptor(names, values);
|
|
|
|
break;
|
|
case 0:
|
|
descriptor = (Descriptor)in.readObject();
|
|
|
|
if (descriptor == null) {
|
|
descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR;
|
|
}
|
|
|
|
break;
|
|
case -1: // from an earlier version of the JMX API
|
|
descriptor = ImmutableDescriptor.EMPTY_DESCRIPTOR;
|
|
|
|
break;
|
|
default:
|
|
throw new StreamCorruptedException("Got unexpected byte.");
|
|
}
|
|
}
|
|
}
|