package org.apache.velocity.app.event; import org.apache.velocity.context.Context; import org.apache.velocity.util.ContextAware; /* * 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. */ /** * Event handler called when a method throws an exception. This gives the * application a chance to deal with it and either * return something nice, or throw. * * Please return what you want rendered into the output stream. * * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a> * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a> * @version $Id: MethodExceptionEventHandler.java 685685 2008-08-13 21:43:27Z nbubna $ */ public interface MethodExceptionEventHandler extends EventHandler { /** * Called when a method throws an exception. * Only the first registered MethodExceptionEventHandler is called. If * none are registered a MethodInvocationException is thrown. * * @param claz the class of the object the method is being applied to * @param method the method * @param e the thrown exception * @return an object to insert in the page * @throws Exception an exception to be thrown instead inserting an object */ public Object methodException( Class claz, String method, Exception e ) throws Exception; /** * Defines the execution strategy for methodException * @since 1.5 */ static class MethodExceptionExecutor implements EventHandlerMethodExecutor { private Context context; private Class claz; private String method; private Exception e; private Object result; private boolean executed = false; MethodExceptionExecutor( Context context, Class claz, String method, Exception e) { this.context = context; this.claz = claz; this.method = method; this.e = e; } /** * Call the method methodException() * * @param handler call the appropriate method on this handler * @exception Exception generic exception thrown by methodException event handler method call */ public void execute(EventHandler handler) throws Exception { MethodExceptionEventHandler eh = (MethodExceptionEventHandler) handler; if (eh instanceof ContextAware) ((ContextAware) eh).setContext(context); executed = true; result = ((MethodExceptionEventHandler) handler).methodException(claz, method, e); } public Object getReturnValue() { return result; } /** * Only run the first MethodExceptionEventHandler * * @return true after this is executed once. */ public boolean isDone() { return executed; } } }