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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 | +} | |