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/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package groovy.lang;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.Writer;

/*
 * This {@link Interceptor} traces method calls on the proxied object to a log. 
 * By default, the log is simply 
System.out
; however, that can be * changed with the
setWriter(Writer)
method. *

* A message will be written to output before a method is invoked and after a method * is invoked. If methods are nested, and invoke one another, then indentation * of two spaces is written. *

* Here is an example usage on the ArrayList object:
*

 * def proxy = ProxyMetaClass.getInstance(ArrayList.class)
 * proxy.interceptor = new TracingInterceptor()
 * proxy.use {
 *     def list = [1, 2, 3]
 *     assert 3 == list.size()
 *     assert list.contains(1)
 * }
 * 
* Running this code produces this output: *
 * before java.util.ArrayList.size()
 * after  java.util.ArrayList.size()
 * before java.util.ArrayList.contains(java.lang.Integer)
 * after  java.util.ArrayList.contains(java.lang.Integer)
 * 
*/ public class TracingInterceptor implements Interceptor { protected Writer writer = new PrintWriter(System.out); private int indent = 0; /** * Returns the writer associated with this interceptor. */ public Writer getWriter() { return writer; } /** * Changes the writer associated with this interceptor. */ public void setWriter(Writer writer) { this.writer = writer; } public Object beforeInvoke(Object object, String methodName, Object[] arguments) { write(object, methodName, arguments, "before"); indent++ ; return null; } public Object afterInvoke(Object object, String methodName, Object[] arguments, Object result) { indent--; write(object, methodName, arguments, "after "); return result; } public boolean doInvoke() { return true; } private String indent(){ StringBuilder result = new StringBuilder(); for (int i=0; i 0) writer.write(", "); Object argument = arguments[i]; writer.write(argument.getClass().getName()); } writer.write(")"); } }




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