Class PrepareInterceptor

  extended by com.opensymphony.xwork2.interceptor.AbstractInterceptor
      extended by com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
          extended by 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 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:

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>
Date: Nov 5, 2003 2:33:11 AM

Jason Carreira, Philip Luppens, tm_jee, Rene Gielen
See Also:
Preparable, Serialized Form

Field Summary
private static Log _log
private static String ALT_PREPARE_PREFIX
private  boolean alwaysInvokePrepare
private static String PREPARE_PREFIX
private static long serialVersionUID
Fields inherited from class com.opensymphony.xwork2.interceptor.MethodFilterInterceptor
excludeMethods, includeMethods, log
Constructor Summary
Method Summary
 String doIntercept(ActionInvocation invocation)
          Subclasses must override to implement the interceptor logic.
 void setAlwaysInvokePrepare(String alwaysInvokePrepare)
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


private static final long serialVersionUID
See Also:
Constant Field Values


private static final Log _log


private static final String PREPARE_PREFIX
See Also:
Constant Field Values


private static final String ALT_PREPARE_PREFIX
See Also:
Constant Field Values


private boolean alwaysInvokePrepare
Constructor Detail


public PrepareInterceptor()
Method Detail


public void setAlwaysInvokePrepare(String alwaysInvokePrepare)


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
invocation - the action invocation
the result of invocation

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