/*
* $Id$
* Copyright 2002-2007,2009 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 com.opensymphony.xwork2.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.Preparable;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import java.lang.reflect.InvocationTargetException;
/**
* <!-- START SNIPPET: description -->
*
* This interceptor calls <code>prepare()</code> on actions which implement
* {@link Preparable}. This interceptor is very useful for any situation where
* you need to ensure some logic runs before the actual execute method runs.
*
* <p/> A typical use of this is to run some logic to load an object from the
* database so that when parameters are set they can be set on this object. For
* example, suppose you have a User object with two properties: <i>id</i> and
* <i>name</i>. Provided that the params interceptor is called twice (once
* before and once after this interceptor), you can load the User object using
* the id property, and then when the second params interceptor is called the
* parameter <i>user.name</i> will be set, as desired, on the actual object
* loaded from the database. See the example for more info.
*
* <p/>
* <b>Note:</b> Since XWork 2.0.2, this interceptor extends {@link MethodFilterInterceptor}, therefore being
* able to deal with excludeMethods / includeMethods parameters. See [Workflow Interceptor]
* (class {@link DefaultWorkflowInterceptor}) for documentation and examples on how to use this feature.
*
* <p/><b>Update</b>: Added logic to execute a prepare{MethodName} and conditionally
* the a general prepare() Method, depending on the 'alwaysInvokePrepare' parameter/property
* which is by default true. This allows us to run some logic based on the method
* name we specify in the {@link com.opensymphony.xwork2.ActionProxy}. For example, you can specify a
* prepareInput() method that will be run before the invocation of the input method.
*
* <!-- END SNIPPET: description -->
*
* <p/> <u>Interceptor parameters:</u>
*
* <!-- START SNIPPET: parameters -->
*
* <ul>
*
* <li>alwaysInvokePrepare - Default to true. If true, prepare will always be invoked,
* otherwise it will not.</li>
*
* </ul>
*
* <!-- END SNIPPET: parameters -->
*
* <p/> <u>Extending the interceptor:</u>
*
* <p/>
*
* <!-- START SNIPPET: extending -->
*
* There are no known extension points to this interceptor.
*
* <!-- END SNIPPET: extending -->
*
* <p/> <u>Example code:</u>
*
* <pre>
* <!-- START SNIPPET: example -->
* <!-- Calls the params interceptor twice, allowing you to
* pre-load data for the second time parameters are set -->
* <action name="someAction" class="com.examples.SomeAction">
* <interceptor-ref name="params"/>
* <interceptor-ref name="prepare"/>
* <interceptor-ref name="basicStack"/>
* <result name="success">good_result.ftl</result>
* </action>
* <!-- END SNIPPET: example -->
* </pre>
*
* @author Jason Carreira
* @author Philip Luppens
* @author tm_jee
* @see com.opensymphony.xwork2.Preparable
*/
public class PrepareInterceptor extends MethodFilterInterceptor {
private static final long serialVersionUID = -5216969014510719786L;
private final static String PREPARE_PREFIX = "prepare";
private final static String ALT_PREPARE_PREFIX = "prepareDo";
private boolean alwaysInvokePrepare = true;
private boolean firstCallPrepareDo = false;
/**
* Sets if the <code>preapare</code> method should always be executed.
* <p/>
* Default is <tt>true</tt>.
*
* @param alwaysInvokePrepare if <code>prepare</code> should always be executed or not.
*/
public void setAlwaysInvokePrepare(String alwaysInvokePrepare) {
this.alwaysInvokePrepare = Boolean.parseBoolean(alwaysInvokePrepare);
}
/**
* Sets if the <code>prepareDoXXX</code> method should be called first
* <p/>
* Default is <tt>false</tt> for backward compatibility
*
* @param firstCallPrepareDo if <code>prepareDoXXX</code> should be called first
*/
public void setFirstCallPrepareDo(String firstCallPrepareDo) {
this.firstCallPrepareDo = Boolean.parseBoolean(firstCallPrepareDo);
}
@Override
public String doIntercept(ActionInvocation invocation) throws Exception {
Object action = invocation.getAction();
if (action instanceof Preparable) {
try {
String[] prefixes;
if (firstCallPrepareDo) {
prefixes = new String[] {ALT_PREPARE_PREFIX, PREPARE_PREFIX};
} else {
prefixes = new String[] {PREPARE_PREFIX, ALT_PREPARE_PREFIX};
}
PrefixMethodInvocationUtil.invokePrefixMethod(invocation, prefixes);
}
catch (InvocationTargetException e) {
/*
* The invoked method threw an exception and reflection wrapped it
* in an InvocationTargetException.
* If possible re-throw the original exception so that normal
* exception handling will take place.
*/
Throwable cause = e.getCause();
if (cause instanceof Exception) {
throw (Exception) cause;
} else if(cause instanceof Error) {
throw (Error) cause;
} else {
/*
* The cause is not an Exception or Error (must be Throwable) so
* just re-throw the wrapped exception.
*/
throw e;
}
}
if (alwaysInvokePrepare) {
((Preparable) action).prepare();
}
}
return invocation.invoke();
}
}