Class PrepareInterceptor

All Implemented Interfaces:
Serializable, ConditionalInterceptor, Interceptor

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:
  • Constructor Details

    • PrepareInterceptor

      public PrepareInterceptor()
  • Method Details

    • setAlwaysInvokePrepare

      public void setAlwaysInvokePrepare(String alwaysInvokePrepare)
      Sets if the prepare method should always be executed.

      Default is true.

      Parameters:
      alwaysInvokePrepare - if prepare should always be executed or not.
    • setFirstCallPrepareDo

      public void setFirstCallPrepareDo(String firstCallPrepareDo)
      Sets if the prepareDoXXX method should be called first

      Default is false for backward compatibility

      Parameters:
      firstCallPrepareDo - if prepareDoXXX should be called first
    • 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 - in case of any errors