001// Copyright 2005 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.tapestry.listener; 016 017import org.apache.hivemind.util.Defense; 018import org.apache.tapestry.IActionListener; 019import org.apache.tapestry.IComponent; 020import org.apache.tapestry.IRequestCycle; 021 022/** 023 * Terminator implementation for the tapestry.listener.InvokeListener pipeline; this is what finally 024 * turns around and invokes 025 * {@link org.apache.tapestry.IActionListener#actionTriggered(IComponent, IRequestCycle)}. 026 * 027 * @author Howard M. Lewis Ship 028 * @since 4.0 029 */ 030public class ListenerInvokerTerminator implements ListenerInvoker 031{ 032 033 /** 034 * @param listener 035 * to be invoked, may be null if no listener is found (a convienience for all the 036 * places where listeners are optional) 037 * @param source 038 * the component generating the listener "event", to be passed to the listener. Not 039 * generally used, but may not be null. 040 * @param cycle 041 * the current request cycle, to be passed to the listener. 042 * @param delegate 043 * the next invoker in the pipeline 044 */ 045 public void invokeListener(IActionListener listener, IComponent source, IRequestCycle cycle) 046 { 047 Defense.notNull(source, "source"); 048 Defense.notNull(cycle, "cycle"); 049 050 if (listener != null) 051 listener.actionTriggered(source, cycle); 052 } 053 054}