author | smarks |
Mon, 20 Dec 2010 13:47:04 -0800 | |
changeset 7803 | 56bc97d69d93 |
parent 5506 | 202f599c92aa |
child 9035 | 1255eb81cc2f |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1999, 2008, 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 java.lang.reflect; |
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import java.lang.ref.Reference; |
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import java.lang.ref.WeakReference; |
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import java.util.Arrays; |
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import java.util.Collections; |
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import java.util.HashMap; |
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import java.util.HashSet; |
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import java.util.Map; |
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import java.util.Set; |
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import java.util.List; |
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import java.util.WeakHashMap; |
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import sun.misc.ProxyGenerator; |
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/** |
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* {@code Proxy} provides static methods for creating dynamic proxy |
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* classes and instances, and it is also the superclass of all |
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* dynamic proxy classes created by those methods. |
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* |
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* <p>To create a proxy for some interface {@code Foo}: |
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* <pre> |
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* InvocationHandler handler = new MyInvocationHandler(...); |
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* Class proxyClass = Proxy.getProxyClass( |
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* Foo.class.getClassLoader(), new Class[] { Foo.class }); |
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* Foo f = (Foo) proxyClass. |
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* getConstructor(new Class[] { InvocationHandler.class }). |
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* newInstance(new Object[] { handler }); |
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* </pre> |
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* or more simply: |
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* <pre> |
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* Foo f = (Foo) Proxy.newProxyInstance(Foo.class.getClassLoader(), |
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* new Class[] { Foo.class }, |
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* handler); |
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* </pre> |
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* |
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* <p>A <i>dynamic proxy class</i> (simply referred to as a <i>proxy |
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* class</i> below) is a class that implements a list of interfaces |
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* specified at runtime when the class is created, with behavior as |
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* described below. |
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* |
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* A <i>proxy interface</i> is such an interface that is implemented |
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* by a proxy class. |
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* |
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* A <i>proxy instance</i> is an instance of a proxy class. |
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* |
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* Each proxy instance has an associated <i>invocation handler</i> |
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* object, which implements the interface {@link InvocationHandler}. |
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* A method invocation on a proxy instance through one of its proxy |
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* interfaces will be dispatched to the {@link InvocationHandler#invoke |
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* invoke} method of the instance's invocation handler, passing the proxy |
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* instance, a {@code java.lang.reflect.Method} object identifying |
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* the method that was invoked, and an array of type {@code Object} |
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* containing the arguments. The invocation handler processes the |
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* encoded method invocation as appropriate and the result that it |
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* returns will be returned as the result of the method invocation on |
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* the proxy instance. |
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* |
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* <p>A proxy class has the following properties: |
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* |
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* <ul> |
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* <li>Proxy classes are public, final, and not abstract. |
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* |
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* <li>The unqualified name of a proxy class is unspecified. The space |
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* of class names that begin with the string {@code "$Proxy"} |
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* should be, however, reserved for proxy classes. |
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* |
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* <li>A proxy class extends {@code java.lang.reflect.Proxy}. |
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* |
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* <li>A proxy class implements exactly the interfaces specified at its |
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* creation, in the same order. |
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* |
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* <li>If a proxy class implements a non-public interface, then it will |
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* be defined in the same package as that interface. Otherwise, the |
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* package of a proxy class is also unspecified. Note that package |
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* sealing will not prevent a proxy class from being successfully defined |
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* in a particular package at runtime, and neither will classes already |
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* defined by the same class loader and the same package with particular |
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* signers. |
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* |
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* <li>Since a proxy class implements all of the interfaces specified at |
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* its creation, invoking {@code getInterfaces} on its |
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* {@code Class} object will return an array containing the same |
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* list of interfaces (in the order specified at its creation), invoking |
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* {@code getMethods} on its {@code Class} object will return |
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* an array of {@code Method} objects that include all of the |
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* methods in those interfaces, and invoking {@code getMethod} will |
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* find methods in the proxy interfaces as would be expected. |
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* |
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* <li>The {@link Proxy#isProxyClass Proxy.isProxyClass} method will |
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* return true if it is passed a proxy class-- a class returned by |
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* {@code Proxy.getProxyClass} or the class of an object returned by |
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* {@code Proxy.newProxyInstance}-- and false otherwise. |
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* |
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* <li>The {@code java.security.ProtectionDomain} of a proxy class |
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* is the same as that of system classes loaded by the bootstrap class |
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* loader, such as {@code java.lang.Object}, because the code for a |
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* proxy class is generated by trusted system code. This protection |
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* domain will typically be granted |
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* {@code java.security.AllPermission}. |
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* |
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* <li>Each proxy class has one public constructor that takes one argument, |
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* an implementation of the interface {@link InvocationHandler}, to set |
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* the invocation handler for a proxy instance. Rather than having to use |
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* the reflection API to access the public constructor, a proxy instance |
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* can be also be created by calling the {@link Proxy#newProxyInstance |
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* Proxy.newProxyInstance} method, which combines the actions of calling |
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* {@link Proxy#getProxyClass Proxy.getProxyClass} with invoking the |
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* constructor with an invocation handler. |
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* </ul> |
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* |
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* <p>A proxy instance has the following properties: |
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* |
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* <ul> |
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* <li>Given a proxy instance {@code proxy} and one of the |
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* interfaces implemented by its proxy class {@code Foo}, the |
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* following expression will return true: |
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* <pre> |
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* {@code proxy instanceof Foo} |
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* </pre> |
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* and the following cast operation will succeed (rather than throwing |
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* a {@code ClassCastException}): |
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* <pre> |
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* {@code (Foo) proxy} |
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* </pre> |
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* |
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* <li>Each proxy instance has an associated invocation handler, the one |
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* that was passed to its constructor. The static |
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* {@link Proxy#getInvocationHandler Proxy.getInvocationHandler} method |
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* will return the invocation handler associated with the proxy instance |
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* passed as its argument. |
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* |
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* <li>An interface method invocation on a proxy instance will be |
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* encoded and dispatched to the invocation handler's {@link |
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* InvocationHandler#invoke invoke} method as described in the |
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* documentation for that method. |
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* |
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* <li>An invocation of the {@code hashCode}, |
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* {@code equals}, or {@code toString} methods declared in |
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* {@code java.lang.Object} on a proxy instance will be encoded and |
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* dispatched to the invocation handler's {@code invoke} method in |
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* the same manner as interface method invocations are encoded and |
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* dispatched, as described above. The declaring class of the |
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* {@code Method} object passed to {@code invoke} will be |
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* {@code java.lang.Object}. Other public methods of a proxy |
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* instance inherited from {@code java.lang.Object} are not |
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* overridden by a proxy class, so invocations of those methods behave |
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* like they do for instances of {@code java.lang.Object}. |
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* </ul> |
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* |
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* <h3>Methods Duplicated in Multiple Proxy Interfaces</h3> |
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* |
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* <p>When two or more interfaces of a proxy class contain a method with |
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* the same name and parameter signature, the order of the proxy class's |
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* interfaces becomes significant. When such a <i>duplicate method</i> |
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* is invoked on a proxy instance, the {@code Method} object passed |
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* to the invocation handler will not necessarily be the one whose |
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* declaring class is assignable from the reference type of the interface |
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* that the proxy's method was invoked through. This limitation exists |
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* because the corresponding method implementation in the generated proxy |
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* class cannot determine which interface it was invoked through. |
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* Therefore, when a duplicate method is invoked on a proxy instance, |
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* the {@code Method} object for the method in the foremost interface |
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* that contains the method (either directly or inherited through a |
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* superinterface) in the proxy class's list of interfaces is passed to |
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* the invocation handler's {@code invoke} method, regardless of the |
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* reference type through which the method invocation occurred. |
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* |
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* <p>If a proxy interface contains a method with the same name and |
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* parameter signature as the {@code hashCode}, {@code equals}, |
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* or {@code toString} methods of {@code java.lang.Object}, |
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* when such a method is invoked on a proxy instance, the |
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* {@code Method} object passed to the invocation handler will have |
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* {@code java.lang.Object} as its declaring class. In other words, |
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* the public, non-final methods of {@code java.lang.Object} |
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* logically precede all of the proxy interfaces for the determination of |
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* which {@code Method} object to pass to the invocation handler. |
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* |
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* <p>Note also that when a duplicate method is dispatched to an |
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* invocation handler, the {@code invoke} method may only throw |
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* checked exception types that are assignable to one of the exception |
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* types in the {@code throws} clause of the method in <i>all</i> of |
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* the proxy interfaces that it can be invoked through. If the |
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* {@code invoke} method throws a checked exception that is not |
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* assignable to any of the exception types declared by the method in one |
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* of the proxy interfaces that it can be invoked through, then an |
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* unchecked {@code UndeclaredThrowableException} will be thrown by |
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* the invocation on the proxy instance. This restriction means that not |
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* all of the exception types returned by invoking |
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* {@code getExceptionTypes} on the {@code Method} object |
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* passed to the {@code invoke} method can necessarily be thrown |
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* successfully by the {@code invoke} method. |
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* |
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* @author Peter Jones |
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* @see InvocationHandler |
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* @since 1.3 |
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*/ |
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public class Proxy implements java.io.Serializable { |
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private static final long serialVersionUID = -2222568056686623797L; |
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/** prefix for all proxy class names */ |
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private final static String proxyClassNamePrefix = "$Proxy"; |
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/** parameter types of a proxy class constructor */ |
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private final static Class[] constructorParams = |
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{ InvocationHandler.class }; |
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/** maps a class loader to the proxy class cache for that loader */ |
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private static Map<ClassLoader, Map<List<String>, Object>> loaderToCache |
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= new WeakHashMap<>(); |
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/** marks that a particular proxy class is currently being generated */ |
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private static Object pendingGenerationMarker = new Object(); |
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/** next number to use for generation of unique proxy class names */ |
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private static long nextUniqueNumber = 0; |
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private static Object nextUniqueNumberLock = new Object(); |
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/** set of all generated proxy classes, for isProxyClass implementation */ |
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private static Map<Class<?>, Void> proxyClasses = |
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Collections.synchronizedMap(new WeakHashMap<Class<?>, Void>()); |
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/** |
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* the invocation handler for this proxy instance. |
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* @serial |
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*/ |
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protected InvocationHandler h; |
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/** |
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* Prohibits instantiation. |
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*/ |
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private Proxy() { |
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} |
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/** |
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* Constructs a new {@code Proxy} instance from a subclass |
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* (typically, a dynamic proxy class) with the specified value |
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* for its invocation handler. |
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* |
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* @param h the invocation handler for this proxy instance |
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*/ |
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protected Proxy(InvocationHandler h) { |
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this.h = h; |
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} |
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/** |
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* Returns the {@code java.lang.Class} object for a proxy class |
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* given a class loader and an array of interfaces. The proxy class |
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* will be defined by the specified class loader and will implement |
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* all of the supplied interfaces. If a proxy class for the same |
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* permutation of interfaces has already been defined by the class |
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* loader, then the existing proxy class will be returned; otherwise, |
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* a proxy class for those interfaces will be generated dynamically |
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* and defined by the class loader. |
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* |
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* <p>There are several restrictions on the parameters that may be |
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* passed to {@code Proxy.getProxyClass}: |
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* |
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* <ul> |
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* <li>All of the {@code Class} objects in the |
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* {@code interfaces} array must represent interfaces, not |
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* classes or primitive types. |
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* |
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* <li>No two elements in the {@code interfaces} array may |
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* refer to identical {@code Class} objects. |
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* |
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* <li>All of the interface types must be visible by name through the |
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* specified class loader. In other words, for class loader |
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* {@code cl} and every interface {@code i}, the following |
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* expression must be true: |
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* <pre> |
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* Class.forName(i.getName(), false, cl) == i |
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* </pre> |
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* |
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* <li>All non-public interfaces must be in the same package; |
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* otherwise, it would not be possible for the proxy class to |
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* implement all of the interfaces, regardless of what package it is |
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* defined in. |
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* |
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* <li>For any set of member methods of the specified interfaces |
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* that have the same signature: |
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* <ul> |
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* <li>If the return type of any of the methods is a primitive |
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* type or void, then all of the methods must have that same |
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* return type. |
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* <li>Otherwise, one of the methods must have a return type that |
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* is assignable to all of the return types of the rest of the |
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* methods. |
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* </ul> |
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* |
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* <li>The resulting proxy class must not exceed any limits imposed |
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* on classes by the virtual machine. For example, the VM may limit |
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* the number of interfaces that a class may implement to 65535; in |
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* that case, the size of the {@code interfaces} array must not |
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* exceed 65535. |
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* </ul> |
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* |
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* <p>If any of these restrictions are violated, |
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* {@code Proxy.getProxyClass} will throw an |
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* {@code IllegalArgumentException}. If the {@code interfaces} |
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* array argument or any of its elements are {@code null}, a |
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* {@code NullPointerException} will be thrown. |
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* |
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* <p>Note that the order of the specified proxy interfaces is |
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* significant: two requests for a proxy class with the same combination |
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* of interfaces but in a different order will result in two distinct |
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* proxy classes. |
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* |
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* @param loader the class loader to define the proxy class |
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* @param interfaces the list of interfaces for the proxy class |
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* to implement |
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* @return a proxy class that is defined in the specified class loader |
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* and that implements the specified interfaces |
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* @throws IllegalArgumentException if any of the restrictions on the |
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* parameters that may be passed to {@code getProxyClass} |
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* are violated |
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* @throws NullPointerException if the {@code interfaces} array |
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* argument or any of its elements are {@code null} |
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*/ |
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public static Class<?> getProxyClass(ClassLoader loader, |
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Class<?>... interfaces) |
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throws IllegalArgumentException |
|
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{ |
|
349 |
if (interfaces.length > 65535) { |
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350 |
throw new IllegalArgumentException("interface limit exceeded"); |
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351 |
} |
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Class<?> proxyClass = null; |
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/* collect interface names to use as key for proxy class cache */ |
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String[] interfaceNames = new String[interfaces.length]; |
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51 | 358 |
// for detecting duplicates |
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Set<Class<?>> interfaceSet = new HashSet<>(); |
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for (int i = 0; i < interfaces.length; i++) { |
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/* |
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363 |
* Verify that the class loader resolves the name of this |
|
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* interface to the same Class object. |
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*/ |
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String interfaceName = interfaces[i].getName(); |
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Class<?> interfaceClass = null; |
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try { |
369 |
interfaceClass = Class.forName(interfaceName, false, loader); |
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} catch (ClassNotFoundException e) { |
|
371 |
} |
|
372 |
if (interfaceClass != interfaces[i]) { |
|
373 |
throw new IllegalArgumentException( |
|
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interfaces[i] + " is not visible from class loader"); |
|
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} |
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||
377 |
/* |
|
378 |
* Verify that the Class object actually represents an |
|
379 |
* interface. |
|
380 |
*/ |
|
381 |
if (!interfaceClass.isInterface()) { |
|
382 |
throw new IllegalArgumentException( |
|
383 |
interfaceClass.getName() + " is not an interface"); |
|
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} |
|
385 |
||
386 |
/* |
|
387 |
* Verify that this interface is not a duplicate. |
|
388 |
*/ |
|
389 |
if (interfaceSet.contains(interfaceClass)) { |
|
390 |
throw new IllegalArgumentException( |
|
391 |
"repeated interface: " + interfaceClass.getName()); |
|
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} |
|
393 |
interfaceSet.add(interfaceClass); |
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394 |
||
395 |
interfaceNames[i] = interfaceName; |
|
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} |
|
397 |
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/* |
|
399 |
* Using string representations of the proxy interfaces as |
|
400 |
* keys in the proxy class cache (instead of their Class |
|
401 |
* objects) is sufficient because we require the proxy |
|
402 |
* interfaces to be resolvable by name through the supplied |
|
403 |
* class loader, and it has the advantage that using a string |
|
404 |
* representation of a class makes for an implicit weak |
|
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* reference to the class. |
|
406 |
*/ |
|
51 | 407 |
List<String> key = Arrays.asList(interfaceNames); |
2 | 408 |
|
409 |
/* |
|
410 |
* Find or create the proxy class cache for the class loader. |
|
411 |
*/ |
|
51 | 412 |
Map<List<String>, Object> cache; |
2 | 413 |
synchronized (loaderToCache) { |
51 | 414 |
cache = loaderToCache.get(loader); |
2 | 415 |
if (cache == null) { |
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|
416 |
cache = new HashMap<>(); |
2 | 417 |
loaderToCache.put(loader, cache); |
418 |
} |
|
419 |
/* |
|
420 |
* This mapping will remain valid for the duration of this |
|
421 |
* method, without further synchronization, because the mapping |
|
422 |
* will only be removed if the class loader becomes unreachable. |
|
423 |
*/ |
|
424 |
} |
|
425 |
||
426 |
/* |
|
427 |
* Look up the list of interfaces in the proxy class cache using |
|
428 |
* the key. This lookup will result in one of three possible |
|
429 |
* kinds of values: |
|
430 |
* null, if there is currently no proxy class for the list of |
|
431 |
* interfaces in the class loader, |
|
432 |
* the pendingGenerationMarker object, if a proxy class for the |
|
433 |
* list of interfaces is currently being generated, |
|
434 |
* or a weak reference to a Class object, if a proxy class for |
|
435 |
* the list of interfaces has already been generated. |
|
436 |
*/ |
|
437 |
synchronized (cache) { |
|
438 |
/* |
|
439 |
* Note that we need not worry about reaping the cache for |
|
440 |
* entries with cleared weak references because if a proxy class |
|
441 |
* has been garbage collected, its class loader will have been |
|
442 |
* garbage collected as well, so the entire cache will be reaped |
|
443 |
* from the loaderToCache map. |
|
444 |
*/ |
|
445 |
do { |
|
446 |
Object value = cache.get(key); |
|
447 |
if (value instanceof Reference) { |
|
51 | 448 |
proxyClass = (Class<?>) ((Reference) value).get(); |
2 | 449 |
} |
450 |
if (proxyClass != null) { |
|
451 |
// proxy class already generated: return it |
|
452 |
return proxyClass; |
|
453 |
} else if (value == pendingGenerationMarker) { |
|
454 |
// proxy class being generated: wait for it |
|
455 |
try { |
|
456 |
cache.wait(); |
|
457 |
} catch (InterruptedException e) { |
|
458 |
/* |
|
459 |
* The class generation that we are waiting for should |
|
460 |
* take a small, bounded time, so we can safely ignore |
|
461 |
* thread interrupts here. |
|
462 |
*/ |
|
463 |
} |
|
464 |
continue; |
|
465 |
} else { |
|
466 |
/* |
|
467 |
* No proxy class for this list of interfaces has been |
|
468 |
* generated or is being generated, so we will go and |
|
469 |
* generate it now. Mark it as pending generation. |
|
470 |
*/ |
|
471 |
cache.put(key, pendingGenerationMarker); |
|
472 |
break; |
|
473 |
} |
|
474 |
} while (true); |
|
475 |
} |
|
476 |
||
477 |
try { |
|
478 |
String proxyPkg = null; // package to define proxy class in |
|
479 |
||
480 |
/* |
|
481 |
* Record the package of a non-public proxy interface so that the |
|
482 |
* proxy class will be defined in the same package. Verify that |
|
483 |
* all non-public proxy interfaces are in the same package. |
|
484 |
*/ |
|
485 |
for (int i = 0; i < interfaces.length; i++) { |
|
486 |
int flags = interfaces[i].getModifiers(); |
|
487 |
if (!Modifier.isPublic(flags)) { |
|
488 |
String name = interfaces[i].getName(); |
|
489 |
int n = name.lastIndexOf('.'); |
|
490 |
String pkg = ((n == -1) ? "" : name.substring(0, n + 1)); |
|
491 |
if (proxyPkg == null) { |
|
492 |
proxyPkg = pkg; |
|
493 |
} else if (!pkg.equals(proxyPkg)) { |
|
494 |
throw new IllegalArgumentException( |
|
495 |
"non-public interfaces from different packages"); |
|
496 |
} |
|
497 |
} |
|
498 |
} |
|
499 |
||
500 |
if (proxyPkg == null) { // if no non-public proxy interfaces, |
|
501 |
proxyPkg = ""; // use the unnamed package |
|
502 |
} |
|
503 |
||
504 |
{ |
|
505 |
/* |
|
506 |
* Choose a name for the proxy class to generate. |
|
507 |
*/ |
|
508 |
long num; |
|
509 |
synchronized (nextUniqueNumberLock) { |
|
510 |
num = nextUniqueNumber++; |
|
511 |
} |
|
512 |
String proxyName = proxyPkg + proxyClassNamePrefix + num; |
|
513 |
/* |
|
514 |
* Verify that the class loader hasn't already |
|
515 |
* defined a class with the chosen name. |
|
516 |
*/ |
|
517 |
||
518 |
/* |
|
519 |
* Generate the specified proxy class. |
|
520 |
*/ |
|
521 |
byte[] proxyClassFile = ProxyGenerator.generateProxyClass( |
|
522 |
proxyName, interfaces); |
|
523 |
try { |
|
524 |
proxyClass = defineClass0(loader, proxyName, |
|
525 |
proxyClassFile, 0, proxyClassFile.length); |
|
526 |
} catch (ClassFormatError e) { |
|
527 |
/* |
|
528 |
* A ClassFormatError here means that (barring bugs in the |
|
529 |
* proxy class generation code) there was some other |
|
530 |
* invalid aspect of the arguments supplied to the proxy |
|
531 |
* class creation (such as virtual machine limitations |
|
532 |
* exceeded). |
|
533 |
*/ |
|
534 |
throw new IllegalArgumentException(e.toString()); |
|
535 |
} |
|
536 |
} |
|
537 |
// add to set of all generated proxy classes, for isProxyClass |
|
538 |
proxyClasses.put(proxyClass, null); |
|
539 |
||
540 |
} finally { |
|
541 |
/* |
|
542 |
* We must clean up the "pending generation" state of the proxy |
|
543 |
* class cache entry somehow. If a proxy class was successfully |
|
544 |
* generated, store it in the cache (with a weak reference); |
|
545 |
* otherwise, remove the reserved entry. In all cases, notify |
|
546 |
* all waiters on reserved entries in this cache. |
|
547 |
*/ |
|
548 |
synchronized (cache) { |
|
549 |
if (proxyClass != null) { |
|
51 | 550 |
cache.put(key, new WeakReference<Class<?>>(proxyClass)); |
2 | 551 |
} else { |
552 |
cache.remove(key); |
|
553 |
} |
|
554 |
cache.notifyAll(); |
|
555 |
} |
|
556 |
} |
|
557 |
return proxyClass; |
|
558 |
} |
|
559 |
||
560 |
/** |
|
561 |
* Returns an instance of a proxy class for the specified interfaces |
|
562 |
* that dispatches method invocations to the specified invocation |
|
563 |
* handler. This method is equivalent to: |
|
564 |
* <pre> |
|
565 |
* Proxy.getProxyClass(loader, interfaces). |
|
566 |
* getConstructor(new Class[] { InvocationHandler.class }). |
|
567 |
* newInstance(new Object[] { handler }); |
|
568 |
* </pre> |
|
569 |
* |
|
570 |
* <p>{@code Proxy.newProxyInstance} throws |
|
571 |
* {@code IllegalArgumentException} for the same reasons that |
|
572 |
* {@code Proxy.getProxyClass} does. |
|
573 |
* |
|
574 |
* @param loader the class loader to define the proxy class |
|
575 |
* @param interfaces the list of interfaces for the proxy class |
|
576 |
* to implement |
|
577 |
* @param h the invocation handler to dispatch method invocations to |
|
578 |
* @return a proxy instance with the specified invocation handler of a |
|
579 |
* proxy class that is defined by the specified class loader |
|
580 |
* and that implements the specified interfaces |
|
581 |
* @throws IllegalArgumentException if any of the restrictions on the |
|
582 |
* parameters that may be passed to {@code getProxyClass} |
|
583 |
* are violated |
|
584 |
* @throws NullPointerException if the {@code interfaces} array |
|
585 |
* argument or any of its elements are {@code null}, or |
|
586 |
* if the invocation handler, {@code h}, is |
|
587 |
* {@code null} |
|
588 |
*/ |
|
589 |
public static Object newProxyInstance(ClassLoader loader, |
|
590 |
Class<?>[] interfaces, |
|
591 |
InvocationHandler h) |
|
592 |
throws IllegalArgumentException |
|
593 |
{ |
|
594 |
if (h == null) { |
|
595 |
throw new NullPointerException(); |
|
596 |
} |
|
597 |
||
598 |
/* |
|
599 |
* Look up or generate the designated proxy class. |
|
600 |
*/ |
|
51 | 601 |
Class<?> cl = getProxyClass(loader, interfaces); |
2 | 602 |
|
603 |
/* |
|
604 |
* Invoke its constructor with the designated invocation handler. |
|
605 |
*/ |
|
606 |
try { |
|
607 |
Constructor cons = cl.getConstructor(constructorParams); |
|
51 | 608 |
return cons.newInstance(new Object[] { h }); |
2 | 609 |
} catch (NoSuchMethodException e) { |
610 |
throw new InternalError(e.toString()); |
|
611 |
} catch (IllegalAccessException e) { |
|
612 |
throw new InternalError(e.toString()); |
|
613 |
} catch (InstantiationException e) { |
|
614 |
throw new InternalError(e.toString()); |
|
615 |
} catch (InvocationTargetException e) { |
|
616 |
throw new InternalError(e.toString()); |
|
617 |
} |
|
618 |
} |
|
619 |
||
620 |
/** |
|
621 |
* Returns true if and only if the specified class was dynamically |
|
622 |
* generated to be a proxy class using the {@code getProxyClass} |
|
623 |
* method or the {@code newProxyInstance} method. |
|
624 |
* |
|
625 |
* <p>The reliability of this method is important for the ability |
|
626 |
* to use it to make security decisions, so its implementation should |
|
627 |
* not just test if the class in question extends {@code Proxy}. |
|
628 |
* |
|
629 |
* @param cl the class to test |
|
630 |
* @return {@code true} if the class is a proxy class and |
|
631 |
* {@code false} otherwise |
|
632 |
* @throws NullPointerException if {@code cl} is {@code null} |
|
633 |
*/ |
|
634 |
public static boolean isProxyClass(Class<?> cl) { |
|
635 |
if (cl == null) { |
|
636 |
throw new NullPointerException(); |
|
637 |
} |
|
638 |
||
639 |
return proxyClasses.containsKey(cl); |
|
640 |
} |
|
641 |
||
642 |
/** |
|
643 |
* Returns the invocation handler for the specified proxy instance. |
|
644 |
* |
|
645 |
* @param proxy the proxy instance to return the invocation handler for |
|
646 |
* @return the invocation handler for the proxy instance |
|
647 |
* @throws IllegalArgumentException if the argument is not a |
|
648 |
* proxy instance |
|
649 |
*/ |
|
650 |
public static InvocationHandler getInvocationHandler(Object proxy) |
|
651 |
throws IllegalArgumentException |
|
652 |
{ |
|
653 |
/* |
|
654 |
* Verify that the object is actually a proxy instance. |
|
655 |
*/ |
|
656 |
if (!isProxyClass(proxy.getClass())) { |
|
657 |
throw new IllegalArgumentException("not a proxy instance"); |
|
658 |
} |
|
659 |
||
660 |
Proxy p = (Proxy) proxy; |
|
661 |
return p.h; |
|
662 |
} |
|
663 |
||
664 |
private static native Class defineClass0(ClassLoader loader, String name, |
|
665 |
byte[] b, int off, int len); |
|
666 |
} |