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## 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

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.
`void` | `setFirstCallPrepareDo(String firstCallPrepareDo)` Sets if the `prepareDoXXX` method should be called first Default is `false` for backward compatibility

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`

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.

### 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`

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