org.apache.struts2.interceptor

## Class ScopeInterceptor

- java.lang.Object
- - com.opensymphony.xwork2.interceptor.AbstractInterceptor
  - - org.apache.struts2.interceptor.ScopeInterceptor

- All Implemented Interfaces:
    Interceptor, PreResultListener, Serializable

      public class ScopeInterceptor
      extends AbstractInterceptor
      implements PreResultListener

  This is designed to solve a few simple issues related to wizard-like functionality in Struts. One of those issues is that some applications have a application-wide parameters commonly used, such pageLen (used for records per page). Rather than requiring that each action check if such parameters are supplied, this interceptor can look for specified parameters and pull them out of the session.

  This works by setting listed properties at action start with values from session/application attributes keyed after the action's class, the action's name, or any supplied key. After action is executed all the listed properties are taken back and put in session or application context.

  To make sure that each execution of the action is consistent it makes use of session-level locking. This way it guarantees that each action execution is atomic at the session level. It doesn't guarantee application level consistency however there has yet to be enough reasons to do so. Application level consistency would also be a big performance overkill.

  Note that this interceptor takes a snapshot of action properties just before result is presented (using a `PreResultListener`), rather than after action is invoked. There is a reason for that: At this moment we know that action's state is "complete" as it's values may depend on the rest of the stack and specifically - on the values of nested interceptors.

  Interceptor parameters:

  - session - a list of action properties to be bound to session scope
  - application - a list of action properties to be bound to application scope
  - key - a session/application attribute key prefix, can contain following values:
    - CLASS - that creates a unique key prefix based on action namespace and action class, it's a default value
    - ACTION - creates a unique key prefix based on action namespace and action name
    - any other value is taken literally as key prefix
  - type - with one of the following
    - start - means it's a start action of the wizard-like action sequence and all session scoped properties are reset to their defaults
    - end - means that session scoped properties are removed from session after action is run
    - any other value throws IllegalArgumentException
  - sessionReset - name of a parameter (defaults to 'session.reset') which if set, causes all session values to be reset to action's default values or application scope values, note that it is similar to type="start" and in fact it does the same, but in our team it is sometimes semantically preferred. We use session scope in two patterns - sometimes there are wizard-like action sequences that have start and end, and sometimes we just want simply reset current session values.
  - reset - boolean, defaults to false, if set, it has the same effect as setting all session values to be reset to action's default values or application.
  - autoCreateSession - boolean value, sets if the session should be automatically created.

  Extending the interceptor:

  There are no know extension points for this interceptor.

  Example code:

       <!-- As the filter and orderBy parameters are common for all my browse-type actions,
            you can move control to the scope interceptor. In the session parameter you can list
            action properties that are going to be automatically managed over session. You can
            do the same for application-scoped variables-->
       <action name="someAction" class="com.examples.SomeAction">
           <interceptor-ref name="basicStack"/>
           <interceptor-ref name="hibernate"/>
           <interceptor-ref name="scope">
               <param name="session">filter,orderBy</param>
               <param name="autoCreateSession">true</param>
           </interceptor-ref>
           <result name="success">good_result.ftl</result>
       </action>

  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `ScopeInterceptor()` The constructor

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected void` | `after(ActionInvocation invocation, String result)`
    `protected void` | `before(ActionInvocation invocation)`
    `void` | `beforeResult(ActionInvocation invocation, String resultCode)` This callback method will be called after the `Action` execution and before the `Result` execution.
    `String` | `getSessionReset()`
    `String` | `getType()`
    `String` | `intercept(ActionInvocation invocation)` Override to handle interception
    `boolean` | `isReset()`
    `void` | `setApplication(String s)` Sets a list of application scoped properties
    `void` | `setAutoCreateSession(String value)` Sets if the session should be automatically created
    `void` | `setKey(String key)`
    `void` | `setReset(boolean reset)`
    `void` | `setSession(String s)` Sets a list of session scoped properties
    `void` | `setSessionReset(String sessionReset)`
    `void` | `setType(String type)` Sets the type of scope operation

    - ### 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

    - #### ScopeInterceptor

          public ScopeInterceptor()

      The constructor

  - ### Method Detail

    - #### setApplication

          public void setApplication(String s)

      Sets a list of application scoped properties
      Parameters:
        `s` - A comma-delimited list

    - #### setSession

          public void setSession(String s)

      Sets a list of session scoped properties
      Parameters:
        `s` - A comma-delimited list

    - #### setAutoCreateSession

          public void setAutoCreateSession(String value)

      Sets if the session should be automatically created
      Parameters:
        `value` - True if it should be created

    - #### after

          protected void after(ActionInvocation invocation,
                   String result)
                        throws Exception

      Throws:
        `Exception`

    - #### before

          protected void before(ActionInvocation invocation)
                         throws Exception

      Throws:
        `Exception`

    - #### setKey

          public void setKey(String key)

    - #### beforeResult

          public void beforeResult(ActionInvocation invocation,
                          String resultCode)

      Description copied from interface: `PreResultListener`
      This callback method will be called after the `Action` execution and before the `Result` execution.
      Specified by:
        `beforeResult` in interface `PreResultListener`
      Parameters:
        `invocation` - the action invocation
        `resultCode` - the result code returned by the action (eg. `success`).

    - #### getType

          public String getType()

      Returns:
        The type of scope operation, "start" or "end"

    - #### setType

          public void setType(String type)

      Sets the type of scope operation
      Parameters:
        `type` - Either "start" or "end"

    - #### getSessionReset

          public String getSessionReset()

      Returns:
        Gets the session reset parameter name

    - #### setSessionReset

          public void setSessionReset(String sessionReset)

      Parameters:
        `sessionReset` - The session reset parameter name

    - #### intercept

          public String intercept(ActionInvocation invocation)
                           throws Exception

      Description copied from class: `AbstractInterceptor`
      Override to handle interception
      Specified by:
        `intercept` in interface `Interceptor`
      Specified by:
        `intercept` in class `AbstractInterceptor`
      Parameters:
        `invocation` - the action invocation
      Returns:
        the return code, either returned from `ActionInvocation.invoke()`, or from the interceptor itself.
      Throws:
        `Exception` - any system-level error, as defined in `Action.execute()`.

    - #### isReset

          public boolean isReset()

      Returns:
        True if the scope is reset

    - #### setReset

          public void setReset(boolean reset)

      Parameters:
        `reset` - True if the scope should be reset

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