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.proxy.invoker;
019
020 import org.apache.commons.proxy.Invoker;
021
022 import java.lang.reflect.Method;
023 import java.util.HashMap;
024 import java.util.Map;
025
026 /**
027 * An {@link Invoker} implementation which merely returns null for all method invocations. This class is
028 * useful for scenarios where the "null object" design pattern is needed.
029 *
030 * @author James Carman
031 * @since 1.0
032 */
033 public class NullInvoker implements Invoker
034 {
035 private static Map primitiveValueMap = new HashMap();
036 static
037 {
038 primitiveValueMap.put( Integer.TYPE, new Integer( 0 ) );
039 primitiveValueMap.put( Long.TYPE, new Long( 0 ) );
040 primitiveValueMap.put( Short.TYPE, new Short( ( short )0 ) );
041 primitiveValueMap.put( Byte.TYPE, new Byte( ( byte )0 ) );
042 primitiveValueMap.put( Float.TYPE, new Float( 0.0f ) );
043 primitiveValueMap.put( Double.TYPE, new Double( 0.0 ) );
044 primitiveValueMap.put( Character.TYPE, new Character( ( char )0 ) );
045 primitiveValueMap.put( Boolean.TYPE, Boolean.FALSE );
046 }
047 //----------------------------------------------------------------------------------------------------------------------
048 // InvocationHandler Implementation
049 //----------------------------------------------------------------------------------------------------------------------
050
051 public Object invoke( Object proxy, Method method, Object[] args ) throws Throwable
052 {
053 final Class returnType = method.getReturnType();
054 if( returnType.isPrimitive() )
055 {
056 return primitiveValueMap.get( returnType );
057 }
058 else
059 {
060 return null;
061 }
062 }
063 }
064