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| 1 | /* | ||
| 2 | * Copyright (c) 1999, 2006, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.lang.reflect; | ||
| 27 | |||
| 28 | /** | ||
| 29 | * {@code InvocationHandler} is the interface implemented by | ||
| 30 | * the <i>invocation handler</i> of a proxy instance. | ||
| 31 | * | ||
| 32 | * <p>Each proxy instance has an associated invocation handler. | ||
| 33 | * When a method is invoked on a proxy instance, the method | ||
| 34 | * invocation is encoded and dispatched to the {@code invoke} | ||
| 35 | * method of its invocation handler. | ||
| 36 | * | ||
| 37 | * @author Peter Jones | ||
| 38 | * @see Proxy | ||
| 39 | * @since 1.3 | ||
| 40 | */ | ||
| 41 | public interface InvocationHandler { | ||
| 42 | |||
| 43 | /** | ||
| 44 | * Processes a method invocation on a proxy instance and returns | ||
| 45 | * the result. This method will be invoked on an invocation handler | ||
| 46 | * when a method is invoked on a proxy instance that it is | ||
| 47 | * associated with. | ||
| 48 | * | ||
| 49 | * @param proxy the proxy instance that the method was invoked on | ||
| 50 | * | ||
| 51 | * @param method the {@code Method} instance corresponding to | ||
| 52 | * the interface method invoked on the proxy instance. The declaring | ||
| 53 | * class of the {@code Method} object will be the interface that | ||
| 54 | * the method was declared in, which may be a superinterface of the | ||
| 55 | * proxy interface that the proxy class inherits the method through. | ||
| 56 | * | ||
| 57 | * @param args an array of objects containing the values of the | ||
| 58 | * arguments passed in the method invocation on the proxy instance, | ||
| 59 | * or {@code null} if interface method takes no arguments. | ||
| 60 | * Arguments of primitive types are wrapped in instances of the | ||
| 61 | * appropriate primitive wrapper class, such as | ||
| 62 | * {@code java.lang.Integer} or {@code java.lang.Boolean}. | ||
| 63 | * | ||
| 64 | * @return the value to return from the method invocation on the | ||
| 65 | * proxy instance. If the declared return type of the interface | ||
| 66 | * method is a primitive type, then the value returned by | ||
| 67 | * this method must be an instance of the corresponding primitive | ||
| 68 | * wrapper class; otherwise, it must be a type assignable to the | ||
| 69 | * declared return type. If the value returned by this method is | ||
| 70 | * {@code null} and the interface method's return type is | ||
| 71 | * primitive, then a {@code NullPointerException} will be | ||
| 72 | * thrown by the method invocation on the proxy instance. If the | ||
| 73 | * value returned by this method is otherwise not compatible with | ||
| 74 | * the interface method's declared return type as described above, | ||
| 75 | * a {@code ClassCastException} will be thrown by the method | ||
| 76 | * invocation on the proxy instance. | ||
| 77 | * | ||
| 78 | * @throws Throwable the exception to throw from the method | ||
| 79 | * invocation on the proxy instance. The exception's type must be | ||
| 80 | * assignable either to any of the exception types declared in the | ||
| 81 | * {@code throws} clause of the interface method or to the | ||
| 82 | * unchecked exception types {@code java.lang.RuntimeException} | ||
| 83 | * or {@code java.lang.Error}. If a checked exception is | ||
| 84 | * thrown by this method that is not assignable to any of the | ||
| 85 | * exception types declared in the {@code throws} clause of | ||
| 86 | * the interface method, then an | ||
| 87 | * {@link UndeclaredThrowableException} containing the | ||
| 88 | * exception that was thrown by this method will be thrown by the | ||
| 89 | * method invocation on the proxy instance. | ||
| 90 | * | ||
| 91 | * @see UndeclaredThrowableException | ||
| 92 | */ | ||
| 93 | public Object invoke(Object proxy, Method method, Object[] args) | ||
| 94 | throws Throwable; | ||
| 95 | } | ||