/*
* $Id: ExceptionCatcher.java 471754 2006-11-06 14:55:09Z husted $
*
* 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.
*/
package org.apache.struts.chain.commands;
import org.apache.commons.chain.Catalog;
import org.apache.commons.chain.CatalogFactory;
import org.apache.commons.chain.Command;
import org.apache.commons.chain.Context;
import org.apache.commons.chain.Filter;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts.chain.contexts.ActionContext;
/**
* <p>Intercept any exception thrown by a subsequent <code>Command</code> in
* this processing chain, and fire the configured exception handler chain
* after storing the exception that has occurred into the
* <code>Context</code>. </p>
*
* @version $Rev: 471754 $ $Date: 2005-11-12 13:01:44 -0500 (Sat, 12 Nov 2005)
* $
*/
public class ExceptionCatcher extends ActionCommandBase implements Filter {
/**
* <p> Provide Commons Logging instance for this class. </p>
*/
private static final Log LOG = LogFactory.getLog(ExceptionCatcher.class);
// ------------------------------------------------------ Instance Variables
/**
* <p> Field for CatalogName property. </p>
*/
private String catalogName = null;
/**
* <p> Field for ExceptionCommand property. </p>
*/
private String exceptionCommand = null;
// -------------------------------------------------------------- Properties
/**
* <p> Return the name of the <code>Catalog</code> in which to perform
* lookups, or <code>null</code> for the default <code>Catalog</code>.
* </p>
*
* @return Name of catalog to use, or null
*/
public String getCatalogName() {
return (this.catalogName);
}
/**
* <p>Set the name of the <code>Catalog</code> in which to perform
* lookups, or <code>null</code> for the default <code>Catalog</code>.</p>
*
* @param catalogName The new catalog name or <code>null</code>
*/
public void setCatalogName(String catalogName) {
this.catalogName = catalogName;
}
/**
* <p> Return the name of the command to be executed if an exception
* occurs. </p>
*
* @return The name of the command to be executed on an exception
*/
public String getExceptionCommand() {
return (this.exceptionCommand);
}
/**
* <p>Set the name of the command to be executed if an exception
* occurs.</p>
*
* @param exceptionCommand The name of the chain to be executed
*/
public void setExceptionCommand(String exceptionCommand) {
this.exceptionCommand = exceptionCommand;
}
// ---------------------------------------------------------- Public Methods
/**
* <p>Clear any existing stored exception and pass the
* <code>context</code> on to the remainder of the current chain.</p>
*
* @param actionCtx The <code>Context</code> for the current request
* @return <code>false</code> so that processing continues
* @throws Exception On any error
*/
public boolean execute(ActionContext actionCtx)
throws Exception {
actionCtx.setException(null);
return (false);
}
/**
* <p>If an exception was thrown by a subsequent <code>Command</code>,
* pass it on to the specified exception handling chain. Otherwise, do
* nothing.</p>
*
* @param context The {@link Context} to be processed by this {@link
* Filter}
* @param exception The <code>Exception</code> (if any) that was thrown by
* the last {@link Command} that was executed; otherwise
* <code>null</code>
* @return TRUE if post processing an exception occurred and the exception
* processing chain invoked
* @throws IllegalStateException If exception throws exception
*/
public boolean postprocess(Context context, Exception exception) {
// Do nothing if there was no exception thrown
if (exception == null) {
return (false);
}
// Stash the exception in the specified context attribute
if (LOG.isDebugEnabled()) {
LOG.debug("Attempting to handle a thrown exception");
}
ActionContext actionCtx = (ActionContext) context;
actionCtx.setException(exception);
// Execute the specified command
try {
Command command = lookupExceptionCommand();
if (command == null) {
LOG.error("Cannot find exceptionCommand '" + exceptionCommand
+ "'");
throw new IllegalStateException(
"Cannot find exceptionCommand '" + exceptionCommand + "'");
}
if (LOG.isTraceEnabled()) {
LOG.trace("Calling exceptionCommand '" + exceptionCommand + "'");
}
command.execute(context);
} catch (Exception e) {
LOG.warn("Exception from exceptionCommand '" + exceptionCommand
+ "'", e);
throw new IllegalStateException("Exception chain threw exception");
}
return (true);
}
/**
* <p> Return the command to be executed if an exception occurs. </p>
*
* @return The command to be executed if an exception occurs
* @throws IllegalArgumentException If catalog cannot be found
* @throws IllegalStateException If command property is not specified
*/
protected Command lookupExceptionCommand() {
String catalogName = getCatalogName();
Catalog catalog;
if (catalogName == null) {
catalog = CatalogFactory.getInstance().getCatalog();
if (catalog == null) {
LOG.error("Cannot find default catalog");
throw new IllegalArgumentException(
"Cannot find default catalog");
}
} else {
catalog = CatalogFactory.getInstance().getCatalog(catalogName);
if (catalog == null) {
LOG.error("Cannot find catalog '" + catalogName + "'");
throw new IllegalArgumentException("Cannot find catalog '"
+ catalogName + "'");
}
}
String exceptionCommand = getExceptionCommand();
if (exceptionCommand == null) {
LOG.error("No exceptionCommand property specified");
throw new IllegalStateException(
"No exceptionCommand property specfied");
}
return catalog.getCommand(exceptionCommand);
}
}