001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.lang3.event;
019
020 import org.apache.commons.lang3.reflect.MethodUtils;
021
022 import java.lang.reflect.InvocationHandler;
023 import java.lang.reflect.InvocationTargetException;
024 import java.lang.reflect.Method;
025 import java.lang.reflect.Proxy;
026 import java.util.Arrays;
027 import java.util.HashSet;
028 import java.util.Set;
029
030 /**
031 * Provides some useful event-based utility methods.
032 *
033 * @since 3.0
034 * @version $Id: EventUtils.java 967237 2010-07-23 20:08:57Z mbenson $
035 */
036 public class EventUtils
037 {
038 /**
039 * Adds an event listener to the specified source. This looks for an "add" method corresponding to the event
040 * type (addActionListener, for example).
041 * @param eventSource the event source
042 * @param listenerType the event listener type
043 * @param listener the listener
044 * @param <L> the event listener type
045 *
046 * @throws IllegalArgumentException if the object doesn't support the listener type
047 */
048 public static <L> void addEventListener(Object eventSource, Class<L> listenerType, L listener)
049 {
050 try
051 {
052 MethodUtils.invokeMethod(eventSource, "add" + listenerType.getSimpleName(), listener);
053 }
054 catch (NoSuchMethodException e)
055 {
056 throw new IllegalArgumentException("Class " + eventSource.getClass().getName() + " does not have a public add" + listenerType.getSimpleName() + " method which takes a parameter of type " + listenerType.getName() + ".");
057 }
058 catch (IllegalAccessException e)
059 {
060 throw new IllegalArgumentException("Class " + eventSource.getClass().getName() + " does not have an accessible add" + listenerType.getSimpleName () + " method which takes a parameter of type " + listenerType.getName() + ".");
061 }
062 catch (InvocationTargetException e)
063 {
064 throw new RuntimeException("Unable to add listener.", e.getCause());
065 }
066 }
067
068 /**
069 * Binds an event listener to a specific method on a specific object.
070 *
071 * @param <L> the event listener type
072 * @param target the target object
073 * @param methodName the name of the method to be called
074 * @param eventSource the object which is generating events (JButton, JList, etc.)
075 * @param listenerType the listener interface (ActionListener.class, SelectionListener.class, etc.)
076 * @param eventTypes the event types (method names) from the listener interface (if none specified, all will be
077 * supported)
078 */
079 public static <L> void bindEventsToMethod(Object target, String methodName, Object eventSource, Class<L> listenerType, String... eventTypes)
080 {
081 final L listener = listenerType.cast(Proxy.newProxyInstance(target.getClass().getClassLoader(), new Class[] { listenerType }, new EventBindingInvocationHandler(target, methodName, eventTypes)));
082 addEventListener(eventSource, listenerType, listener);
083 }
084
085 private static class EventBindingInvocationHandler implements InvocationHandler
086 {
087 private final Object target;
088 private final String methodName;
089 private final Set<String> eventTypes;
090
091 public EventBindingInvocationHandler(final Object target, final String methodName, String[] eventTypes)
092 {
093 this.target = target;
094 this.methodName = methodName;
095 this.eventTypes = new HashSet<String>(Arrays.asList(eventTypes));
096 }
097
098 public Object invoke(final Object proxy, final Method method, final Object[] parameters) throws Throwable
099 {
100 if ( eventTypes.isEmpty() || eventTypes.contains(method.getName()))
101 {
102 if (hasMatchingParametersMethod(method))
103 {
104 return MethodUtils.invokeMethod(target, methodName, parameters);
105 }
106 else
107 {
108 return MethodUtils.invokeMethod(target, methodName);
109 }
110 }
111 return null;
112 }
113
114 private boolean hasMatchingParametersMethod(final Method method)
115 {
116 return MethodUtils.getAccessibleMethod(target.getClass(), methodName, method.getParameterTypes()) != null;
117 }
118 }
119 }