This interceptor calls
prepare()
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.
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 {@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.
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 {@link com.opensymphony.xwork2.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
@author Philip Luppens
@author tm_jee
@see com.opensymphony.xwork2.Preparable