author | darcy |
Wed, 23 Oct 2019 13:01:40 -0700 | |
changeset 58766 | 54ffb15c4839 |
parent 47216 | 71c04702a3d5 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package javax.management.openmbean; |
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import com.sun.jmx.mbeanserver.MXBeanLookup; |
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import com.sun.jmx.mbeanserver.MXBeanMapping; |
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import com.sun.jmx.mbeanserver.MXBeanMappingFactory; |
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import com.sun.jmx.mbeanserver.DefaultMXBeanMappingFactory; |
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import java.lang.reflect.InvocationHandler; |
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import java.lang.reflect.Method; |
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import java.lang.reflect.Proxy; |
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/** |
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<p>An {@link InvocationHandler} that forwards getter methods to a |
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{@link CompositeData}. If you have an interface that contains |
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only getter methods (such as {@code String getName()} or |
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{@code boolean isActive()}) then you can use this class in |
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conjunction with the {@link Proxy} class to produce an implementation |
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of the interface where each getter returns the value of the |
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corresponding item in a {@code CompositeData}.</p> |
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<p>For example, suppose you have an interface like this: |
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<blockquote> |
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<pre> |
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public interface NamedNumber { |
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public int getNumber(); |
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public String getName(); |
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} |
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</pre> |
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</blockquote> |
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and a {@code CompositeData} constructed like this: |
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<blockquote> |
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<pre> |
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CompositeData cd = |
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new {@link CompositeDataSupport}( |
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someCompositeType, |
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new String[] {"number", "name"}, |
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new Object[] {<b>5</b>, "five"} |
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); |
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</pre> |
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</blockquote> |
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then you can construct an object implementing {@code NamedNumber} |
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and backed by the object {@code cd} like this: |
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<blockquote> |
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<pre> |
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InvocationHandler handler = |
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new CompositeDataInvocationHandler(cd); |
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NamedNumber nn = (NamedNumber) |
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Proxy.newProxyInstance(NamedNumber.class.getClassLoader(), |
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new Class[] {NamedNumber.class}, |
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handler); |
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</pre> |
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</blockquote> |
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A call to {@code nn.getNumber()} will then return <b>5</b>. |
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<p>If the first letter of the property defined by a getter is a |
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capital, then this handler will look first for an item in the |
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{@code CompositeData} beginning with a capital, then, if that is |
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not found, for an item beginning with the corresponding lowercase |
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letter or code point. For a getter called {@code getNumber()}, the |
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handler will first look for an item called {@code Number}, then for |
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{@code number}. If the getter is called {@code getnumber()}, then |
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the item must be called {@code number}.</p> |
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<p>If the method given to {@link #invoke invoke} is the method |
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{@code boolean equals(Object)} inherited from {@code Object}, then |
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it will return true if and only if the argument is a {@code Proxy} |
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whose {@code InvocationHandler} is also a {@code |
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CompositeDataInvocationHandler} and whose backing {@code |
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CompositeData} is equal (not necessarily identical) to this |
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object's. If the method given to {@code invoke} is the method |
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{@code int hashCode()} inherited from {@code Object}, then it will |
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return a value that is consistent with this definition of {@code |
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equals}: if two objects are equal according to {@code equals}, then |
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they will have the same {@code hashCode}.</p> |
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@since 1.6 |
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*/ |
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public class CompositeDataInvocationHandler implements InvocationHandler { |
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/** |
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<p>Construct a handler backed by the given {@code |
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CompositeData}.</p> |
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@param compositeData the {@code CompositeData} that will supply |
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information to getters. |
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@throws IllegalArgumentException if {@code compositeData} |
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is null. |
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*/ |
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public CompositeDataInvocationHandler(CompositeData compositeData) { |
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this(compositeData, null); |
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} |
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/** |
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<p>Construct a handler backed by the given {@code |
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CompositeData}.</p> |
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@param compositeData the {@code CompositeData} that will supply |
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information to getters. |
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@throws IllegalArgumentException if {@code compositeData} |
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is null. |
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*/ |
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CompositeDataInvocationHandler(CompositeData compositeData, |
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MXBeanLookup lookup) { |
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if (compositeData == null) |
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throw new IllegalArgumentException("compositeData"); |
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this.compositeData = compositeData; |
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this.lookup = lookup; |
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} |
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/** |
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Return the {@code CompositeData} that was supplied to the |
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constructor. |
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@return the {@code CompositeData} that this handler is backed |
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by. This is never null. |
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*/ |
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public CompositeData getCompositeData() { |
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assert compositeData != null; |
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return compositeData; |
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} |
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public Object invoke(Object proxy, Method method, Object[] args) |
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throws Throwable { |
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final String methodName = method.getName(); |
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// Handle the methods from java.lang.Object |
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if (method.getDeclaringClass() == Object.class) { |
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if (methodName.equals("toString") && args == null) |
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return "Proxy[" + compositeData + "]"; |
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else if (methodName.equals("hashCode") && args == null) |
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return compositeData.hashCode() + 0x43444948; |
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else if (methodName.equals("equals") && args.length == 1 |
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&& method.getParameterTypes()[0] == Object.class) |
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return equals(proxy, args[0]); |
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else { |
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/* Either someone is calling invoke by hand, or |
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it is a non-final method from Object overriden |
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by the generated Proxy. At the time of writing, |
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the only non-final methods in Object that are not |
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handled above are finalize and clone, and these |
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are not overridden in generated proxies. */ |
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// this plain Method.invoke is called only if the declaring class |
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// is Object and so it's safe. |
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return method.invoke(this, args); |
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} |
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} |
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String propertyName = DefaultMXBeanMappingFactory.propertyName(method); |
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if (propertyName == null) { |
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throw new IllegalArgumentException("Method is not getter: " + |
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method.getName()); |
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} |
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Object openValue; |
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if (compositeData.containsKey(propertyName)) |
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openValue = compositeData.get(propertyName); |
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else { |
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String decap = DefaultMXBeanMappingFactory.decapitalize(propertyName); |
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if (compositeData.containsKey(decap)) |
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openValue = compositeData.get(decap); |
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else { |
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final String msg = |
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"No CompositeData item " + propertyName + |
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(decap.equals(propertyName) ? "" : " or " + decap) + |
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" to match " + methodName; |
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throw new IllegalArgumentException(msg); |
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} |
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} |
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MXBeanMapping mapping = |
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MXBeanMappingFactory.DEFAULT.mappingForType(method.getGenericReturnType(), |
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MXBeanMappingFactory.DEFAULT); |
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return mapping.fromOpenValue(openValue); |
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} |
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/* This method is called when equals(Object) is |
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* called on our proxy and hence forwarded to us. For example, if we |
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* are a proxy for an interface like this: |
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* public interface GetString { |
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* public String string(); |
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* } |
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* then we must compare equal to another CompositeDataInvocationHandler |
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* proxy for the same interface and where string() returns the same value. |
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* |
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* You might think that we should also compare equal to another |
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* object that implements GetString directly rather than using |
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* Proxy, provided that its string() returns the same result as |
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* ours, and in fact an earlier version of this class did that (by |
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* converting the other object into a CompositeData and comparing |
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* that with ours). But in fact that doesn't make a great deal of |
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* sense because there's absolutely no guarantee that the |
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* resulting equals would be reflexive (otherObject.equals(this) |
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* might be false even if this.equals(otherObject) is true), and, |
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* especially, there's no way we could generate a hashCode() that |
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* would be equal to otherObject.hashCode() when |
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* this.equals(otherObject), because we don't know how |
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* otherObject.hashCode() is computed. |
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*/ |
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private boolean equals(Object proxy, Object other) { |
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if (other == null) |
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return false; |
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final Class<?> proxyClass = proxy.getClass(); |
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final Class<?> otherClass = other.getClass(); |
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if (proxyClass != otherClass) |
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return false; |
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InvocationHandler otherih = Proxy.getInvocationHandler(other); |
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if (!(otherih instanceof CompositeDataInvocationHandler)) |
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return false; |
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CompositeDataInvocationHandler othercdih = |
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(CompositeDataInvocationHandler) otherih; |
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return compositeData.equals(othercdih.compositeData); |
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} |
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private final CompositeData compositeData; |
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private final MXBeanLookup lookup; |
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} |