org.apache.struts2.interceptor
Class ScopeInterceptor

java.lang.Object
  extended by com.opensymphony.xwork2.interceptor.AbstractInterceptor
      extended by 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:

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

Nested Class Summary
private static class ScopeInterceptor.NULLClass
           
 
Field Summary
private  String[] application
           
private  boolean autoCreateSession
           
private  String key
           
private static Map locks
           
private static Logger LOG
           
private static Object NULL
           
private  boolean reset
           
private static long serialVersionUID
           
private  String[] session
           
private  String sessionReset
           
private  String type
           
 
Constructor Summary
ScopeInterceptor()
          The constructor
 
Method Summary
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.
private  String getKey(ActionInvocation invocation)
           
 String getSessionReset()
           
 String getType()
           
 String intercept(ActionInvocation invocation)
          Override to handle interception
 boolean isReset()
           
(package private) static void lock(Object o, ActionInvocation invocation)
           
private static Object nullConvert(Object o)
           
 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
(package private) static void unlock(Object o)
           
 
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
 

Field Detail

serialVersionUID

private static final long serialVersionUID
See Also:
Constant Field Values

LOG

private static final Logger LOG

application

private String[] application

session

private String[] session

key

private String key

type

private String type

autoCreateSession

private boolean autoCreateSession

sessionReset

private String sessionReset

reset

private boolean reset

NULL

private static final Object NULL

locks

private static Map locks
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

getKey

private String getKey(ActionInvocation invocation)

nullConvert

private static final Object nullConvert(Object o)

lock

static final void lock(Object o,
                       ActionInvocation invocation)
                throws Exception
Throws:
Exception

unlock

static final void unlock(Object o)

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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