org.apache.struts.chain.commands.generic.WrappingLookupCommand Maven / Gradle / Ivy
/*
* $Id: WrappingLookupCommand.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.generic;
import org.apache.commons.beanutils.ConstructorUtils;
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.commands.util.ClassUtils;
import java.lang.reflect.InvocationTargetException;
/**
* Variant on chain LookupCommand which can optionally wrap the context it
* passes to the looked up command in an alternative class.
*/
public class WrappingLookupCommand implements Filter {
/**
* Provide Commons Logging instance for this class.
*/
private static final Log LOG =
LogFactory.getLog(WrappingLookupCommand.class);
// ------------------------------------------------------ Instance Variables
/**
* Field for property.
*/
private String catalogName = null;
/**
* Field for property.
*/
private String name = null;
/**
* Field for property.
*/
private String nameKey = null;
/**
* Field for property.
*/
private String wrapperClassName = null;
/**
* Field for property.
*/
private boolean optional = false;
/**
* Zero-argument constructor.
*/
public WrappingLookupCommand() {
catalogName = null;
name = null;
nameKey = null;
optional = false;
}
/**
* Return CatalogName property.
*
* @return Value of CatalogName property.
*/
public String getCatalogName() {
return catalogName;
}
/**
* Set CatalogName property.
*
* @param catalogName New value for CatalogName
*/
public void setCatalogName(String catalogName) {
this.catalogName = catalogName;
}
/**
* Retrieve Name property.
*
* @return Value of Name property
*/
public String getName() {
return name;
}
/**
* Set Name property.
*
* @param name New value for Name
*/
public void setName(String name) {
this.name = name;
}
/**
* Return NameKey property.
*
* @return Value of NameKey property.
*/
public String getNameKey() {
return nameKey;
}
/**
* Set NameKey property.
*
* @param nameKey New value for NameKey
*/
public void setNameKey(String nameKey) {
this.nameKey = nameKey;
}
/**
* Test Optional property.
*
* @return TRUE if Optional is TRUE.
*/
public boolean isOptional() {
return optional;
}
/**
* Set Optional property.
*
* @param optional New value for Optional
*/
public void setOptional(boolean optional) {
this.optional = optional;
}
/**
* Return the WrapperClass property.
*
* @return The WrapperClass property
*/
public String getWrapperClassName() {
return wrapperClassName;
}
/**
* Set WrappClassName property.
*
* @param wrapperClassName The name of a WrapperClass
*/
public void setWrapperClassName(String wrapperClassName) {
this.wrapperClassName = wrapperClassName;
}
/**
* Invoke the Command for a Context, returning TRUE if processing
* should halt.
*
* @param context Our ActionContext
* @return TRUE if processing should halt
* @throws Exception On any error
*/
public boolean execute(Context context)
throws Exception {
if (LOG.isTraceEnabled()) {
LOG.trace("execute [" + this + "]");
}
Command command = getCommand(context);
if (command != null) {
return command.execute(getContext(context));
} else {
return false;
}
}
/**
* Process the Exception for any Command that is a filter.
*
* @param context Our ActionContext
* @param exception The Exception thrown by another Comamnd in a Chain
* @return TRUE if there is a Filter to process
*/
public boolean postprocess(Context context, Exception exception) {
Command command = getCommand(context);
if ((command != null) && (command instanceof Filter)) {
try {
return ((Filter) command).postprocess(getContext(context),
exception);
} catch (NoSuchMethodException ex) {
LOG.error("Error wrapping context in postprocess", ex);
} catch (IllegalAccessException ex) {
LOG.error("Error wrapping context in postprocess", ex);
} catch (InvocationTargetException ex) {
LOG.error("Error wrapping context in postprocess", ex);
} catch (InstantiationException ex) {
LOG.error("Error wrapping context in postprocess", ex);
} catch (ClassNotFoundException ex) {
LOG.error("Error wrapping context in postprocess", ex);
}
}
return false;
}
/**
* Return the Command to process for this Context.
*
* @param context The Context we are processing
* @return The Command to process for this Context
*/
protected Command getCommand(Context context) {
CatalogFactory catalogFactory = CatalogFactory.getInstance();
String catalogName = getCatalogName();
Catalog catalog;
if (catalogName == null) {
catalog = catalogFactory.getCatalog();
catalogName = "{default}"; // for debugging purposes
} else {
catalog = catalogFactory.getCatalog(catalogName);
}
if (catalog == null) {
throw new IllegalArgumentException("Cannot find catalog '"
+ catalogName + "'");
}
Command command;
String name = getName();
if (name == null) {
name = (String) context.get(getNameKey());
}
if (name != null) {
if (LOG.isDebugEnabled()) {
LOG.debug("Lookup command " + name + " in catalog "
+ catalogName);
}
command = catalog.getCommand(name);
if (LOG.isDebugEnabled()) {
LOG.debug("Found command " + command + ";" + " optional: "
+ isOptional());
}
if ((command == null) && !isOptional()) {
throw new IllegalArgumentException("Cannot find command " + "'"
+ name + "' in catalog '" + catalogName + "'");
} else {
return command;
}
} else {
throw new IllegalArgumentException("No command name");
}
}
/**
* If the wrapperClassName property is not null, return a Context of
* the type specified by wrapperClassName, instantiated using a single-arg
* constructor which takes the context passed as an argument to this
* method.
*
* This method throws an exception if the wrapperClass cannot be found,
* or if there are any errors instantiating the wrapping context.
*
* @param context Context we are processing
* @return Context wrapper
* @throws ClassNotFoundException On failed instantiation
* @throws InstantiationException On failed instantiation
* @throws InvocationTargetException On failed instantiation
* @throws IllegalAccessException On failed instantiation
* @throws NoSuchMethodException On failed instantiation
*/
protected Context getContext(Context context)
throws ClassNotFoundException, InstantiationException,
InvocationTargetException, IllegalAccessException,
NoSuchMethodException {
if (wrapperClassName == null) {
if (LOG.isDebugEnabled()) {
LOG.debug("No defined wrapper class; "
+ "returning original context.");
}
return context;
}
if (LOG.isDebugEnabled()) {
LOG.debug("Looking for wrapper class: " + wrapperClassName);
}
Class wrapperClass = ClassUtils.getApplicationClass(wrapperClassName);
if (LOG.isDebugEnabled()) {
LOG.debug("Instantiating wrapper class");
}
return (Context) ConstructorUtils.invokeConstructor(wrapperClass,
new Object[] { context });
}
}