/*
* Copyright 2003,2004 The Apache Software Foundation.
*
* Licensed 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;
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.Constants;
/**
* <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>
*
* @author Craig R. McClanahan
* @version $Rev: 55324 $ $Date: 2004-10-22 19:55:27 +0100 (Fri, 22 Oct 2004) $
*/
public class ExceptionCatcher implements Filter {
// ------------------------------------------------------ Instance Variables
private String catalogName = null;
private String exceptionCommand = null;
private String exceptionKey = Constants.EXCEPTION_KEY;
private static final Log log = LogFactory.getLog(ExceptionCatcher.class);
// -------------------------------------------------------------- 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>
*/
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>
*/
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;
}
/**
* <p>Return the context attribute key under which any
* thrown exception will be stored.</p>
*/
public String getExceptionKey() {
return (this.exceptionKey);
}
/**
* <p>Set the context attribute key under which any
* thrown exception will be stored.</p>
*
* @param exceptionKey The new context attribute key
*/
public void setExceptionKey(String exceptionKey) {
this.exceptionKey = exceptionKey;
}
// ---------------------------------------------------------- Public Methods
/**
* <p>Clear any existing stored exception and pass the <code>context</code>
* on to the remainder of the current chain.</p>
*
* @param context The <code>Context</code> for the current request
*
* @return <code>false</code> so that processing continues
*/
public boolean execute(Context context) throws Exception {
context.remove(getExceptionKey());
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>
*/
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");
}
context.put(getExceptionKey(), exception);
// Execute the specified command
try {
String catalogName = getCatalogName();
Catalog catalog = null;
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");
}
Command command = catalog.getCommand(exceptionCommand);
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);
}
}