001/* 002 * Copyright 2002-2016 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.aopalliance.intercept; 018 019/** 020 * Intercepts calls on an interface on its way to the target. These 021 * are nested "on top" of the target. 022 * 023 * <p>The user should implement the {@link #invoke(MethodInvocation)} 024 * method to modify the original behavior. E.g. the following class 025 * implements a tracing interceptor (traces all the calls on the 026 * intercepted method(s)): 027 * 028 * <pre class=code> 029 * class TracingInterceptor implements MethodInterceptor { 030 * Object invoke(MethodInvocation i) throws Throwable { 031 * System.out.println("method "+i.getMethod()+" is called on "+ 032 * i.getThis()+" with args "+i.getArguments()); 033 * Object ret=i.proceed(); 034 * System.out.println("method "+i.getMethod()+" returns "+ret); 035 * return ret; 036 * } 037 * } 038 * </pre> 039 * 040 * @author Rod Johnson 041 */ 042public interface MethodInterceptor extends Interceptor { 043 044 /** 045 * Implement this method to perform extra treatments before and 046 * after the invocation. Polite implementations would certainly 047 * like to invoke {@link Joinpoint#proceed()}. 048 * @param invocation the method invocation joinpoint 049 * @return the result of the call to {@link Joinpoint#proceed()}; 050 * might be intercepted by the interceptor 051 * @throws Throwable if the interceptors or the target object 052 * throws an exception 053 */ 054 Object invoke(MethodInvocation invocation) throws Throwable; 055 056}