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    
015    package org.apache.tapestry.components;
016    
017    import org.apache.tapestry.AbstractComponent;
018    import org.apache.tapestry.IActionListener;
019    import org.apache.tapestry.IMarkupWriter;
020    import org.apache.tapestry.IRequestCycle;
021    import org.apache.tapestry.link.DirectLink;
022    import org.apache.tapestry.listener.ListenerInvoker;
023    
024    /**
025     * Invokes a listener method, passing listener parameters. This is used when a
026     * page or component needs some setup logic that can be best accomplished in
027     * Java code. If the listener parameter is not bound, attempt to locate an
028     * implicit listener named by the capitalized component id, prefixed by "do".
029     * 
030     * @author Howard M. Lewis Ship
031     * @since 4.0
032     */
033    public abstract class InvokeListener extends AbstractComponent
034    {
035    
036        protected void renderComponent(IMarkupWriter writer, IRequestCycle cycle)
037        {
038            Object[] parameters = DirectLink
039                    .constructServiceParameters(getParameters());
040    
041            try
042            {
043                cycle.setListenerParameters(parameters);
044    
045                    IActionListener listener = getListener();
046    
047                    if (listener == null)
048                        listener = getContainer().getListeners().getImplicitListener(this);
049    
050                getListenerInvoker().invokeListener(listener, this, cycle);
051            }
052            finally
053            {
054                cycle.setListenerParameters(null);
055            }
056        }
057    
058        /** Parameter. */
059        public abstract IActionListener getListener();
060    
061        /** Parameter. */
062        public abstract Object getParameters();
063    
064        /** Injected. */
065        public abstract ListenerInvoker getListenerInvoker();
066    }