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:
name. Provided that
the params interceptor is called twice (once before and once after this interceptor), you can load the User object using
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
includeMethodsparameters. See Workflow Interceptor 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
alwaysInvokePrepareparameter/property which is by default
true. This allows us to run some logic based on the method name we specify in the
com.opensymphony.xwork2.ActionProxy. For example, you can specify a
prepareInput()method that will be run before the invocation of the input method.
PrepareInterceptor applies only when action implements
1. if the action class have
prepare<MethodName>(), it will be invoked
2. else if the action class have
prepareDo<MethodName>(), it will be invoked
3. no matter if 1] or 2] is performed, if
alwaysInvokePrepare property of the interceptor is
true (which is by
prepare() will be invoked.
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.
<!-- 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>