com.opensymphony.xwork2.interceptor
Class PrepareInterceptor

java.lang.Object
  com.opensymphony.xwork2.interceptor.AbstractInterceptor
      com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
          com.opensymphony.xwork2.interceptor.PrepareInterceptor

All Implemented Interfaces:

Interceptor, Serializable

public class PrepareInterceptor
extends MethodFilterInterceptor

This interceptor calls prepare() on actions which implement Preparable. This interceptor is very useful for any situation where you need to ensure some logic runs before the actual execute method runs.

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: id and name. 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 user.name will be set, as desired, on the actual object loaded from the database. See the example for more info.

Note: Since XWork 2.0.2, this interceptor extends MethodFilterInterceptor, therefore being able to deal with excludeMethods / includeMethods parameters. See [Workflow Interceptor] (class DefaultWorkflowInterceptor) for documentation and examples on how to use this feature.

Update: 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 ActionProxy. For example, you can specify a prepareInput() method that will be run before the invocation of the input method.

Interceptor parameters:

• alwaysInvokePrepare - Default to true. If true, prepare will always be invoked, otherwise it will not.

Extending the interceptor:

There are no known extension points to this interceptor.

Example code:

 
 <!-- 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>
 
 

Author:

Jason Carreira, Philip Luppens, tm_jee

See Also:

Preparable, Serialized Form

Field Summary

private static String	ALT_PREPARE_PREFIX
private boolean	alwaysInvokePrepare
private static Logger	LOG
private static String	PREPARE_PREFIX
private static long	serialVersionUID

Fields inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor

excludeMethods, includeMethods, log

Constructor Summary

PrepareInterceptor()

Method Summary

String	doIntercept(ActionInvocation invocation) Subclasses must override to implement the interceptor logic.
void	setAlwaysInvokePrepare(String alwaysInvokePrepare) Sets if the preapare method should always be executed.

Methods inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor

applyInterceptor, getExcludeMethodsSet, getIncludeMethodsSet, intercept, setExcludeMethods, setIncludeMethods

Methods inherited from class com.opensymphony.xwork2.interceptor.AbstractInterceptor

destroy, init

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

LOG

private static final Logger LOG

PREPARE_PREFIX

private static final String PREPARE_PREFIX

See Also:

Constant Field Values

ALT_PREPARE_PREFIX

private static final String ALT_PREPARE_PREFIX

See Also:

Constant Field Values

alwaysInvokePrepare

private boolean alwaysInvokePrepare

Constructor Detail

PrepareInterceptor

public PrepareInterceptor()

Method Detail

setAlwaysInvokePrepare

public void setAlwaysInvokePrepare(String alwaysInvokePrepare)

Sets if the preapare method should always be executed.

Default is true.

Parameters:

alwaysInvokePrepare - if prepare should always be executed or not.

doIntercept

public String doIntercept(ActionInvocation invocation)
                   throws Exception

Description copied from class: MethodFilterInterceptor

Subclasses must override to implement the interceptor logic.

Specified by:

doIntercept in class MethodFilterInterceptor

Parameters:

invocation - the action invocation

Returns:

the result of invocation

Throws:

Exception