1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package java.lang.reflect; 19 20 /** 21 * Implementors of this interface dispatch methods invoked on proxy instances. 22 * 23 * @see Proxy 24 */ 25 public interface InvocationHandler { 26 27 /** 28 * Handles the method which was originally invoked on the proxy instance. A 29 * typical usage pattern follows below: 30 * 31 * <pre> 32 * public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 33 * //do some processing before the method invocation 34 * 35 * //invoke the method 36 * Object result = method.invoke(proxy, args); 37 * 38 * //do some processing after the method invocation 39 * return result; 40 * }</pre> 41 * 42 * @param proxy 43 * the proxy instance on which the method was invoked 44 * @param method 45 * the method invoked on the proxy instance 46 * @param args 47 * an array of objects containing the parameters passed to the 48 * method, or {@code null} if no arguments are expected. 49 * Primitive types are boxed. 50 * 51 * @return the result of executing the method. Primitive types are boxed. 52 * 53 * @throws Throwable 54 * the exception to throw from the invoked method on the proxy. 55 * The exception must match one of the declared exception types 56 * of the invoked method or any unchecked exception type. If not 57 * then an {@code UndeclaredThrowableException} is thrown 58 */ invoke(Object proxy, Method method, Object[] args)59 public Object invoke(Object proxy, Method method, Object[] args) throws Throwable; 60 } 61