org.apache.struts2

Interface ActionInvocation

All Known Subinterfaces:

ActionInvocation

All Known Implementing Classes:

ActionInvocation.LegacyAdapter, DefaultActionInvocation, MockActionInvocation

public interface ActionInvocation

An ActionInvocation represents the execution state of an Action. It holds the Interceptors and the Action instance. By repeated re-entrant execution of the invoke() method, initially by the ActionProxy, then by the Interceptors, the Interceptors are all executed, and then the Action and the Result.

Author:

Jason Carreira

See Also:

ActionProxy

Method Summary

Modifier and Type	Method and Description
void	addPreResultListener(PreResultListener listener) Register a PreResultListener to be notified after the Action is executed and before the Result is executed.
Object	getAction() Get the Action associated with this ActionInvocation.
ActionContext	getInvocationContext() Gets the ActionContext associated with this ActionInvocation.
ActionProxy	getProxy() Get the ActionProxy holding this ActionInvocation.
Result	getResult() If the ActionInvocation has been executed before and the Result is an instance of ActionChainResult, this method will walk down the chain of ActionChainResults until it finds a non-chain result, which will be returned.
String	getResultCode() Gets the result code returned from this ActionInvocation.
ValueStack	getStack() Gets the ValueStack associated with this ActionInvocation.
void	init(ActionProxy proxy)
String	invoke() Invokes the next step in processing this ActionInvocation.
String	invokeActionOnly() Invokes only the Action (not Interceptors or Results).
boolean	isExecuted() Gets whether this ActionInvocation has executed before.
void	setActionEventListener(ActionEventListener listener) Sets the action event listener to respond to key action events.
void	setResultCode(String resultCode) Sets the result code, possibly overriding the one returned by the action.

Method Detail

getAction

Object getAction()

Get the Action associated with this ActionInvocation.

Returns:

the Action

isExecuted

boolean isExecuted()

Gets whether this ActionInvocation has executed before. This will be set after the Action and the Result have executed.

Returns:

true if this ActionInvocation has executed before.

getInvocationContext

ActionContext getInvocationContext()

Gets the ActionContext associated with this ActionInvocation. The ActionProxy is responsible for setting this ActionContext onto the ThreadLocal before invoking the ActionInvocation and resetting the old ActionContext afterwards.

Returns:

the ActionContext.

getProxy

ActionProxy getProxy()

Get the ActionProxy holding this ActionInvocation.

Returns:

the ActionProxy.

getResult

Result getResult()
          throws Exception

If the ActionInvocation has been executed before and the Result is an instance of ActionChainResult, this method will walk down the chain of ActionChainResults until it finds a non-chain result, which will be returned. If the ActionInvocation's result has not been executed before, the Result instance will be created and populated with the result params.

Returns:

the result.

Throws:

Exception - can be thrown.

getResultCode

String getResultCode()

Gets the result code returned from this ActionInvocation.

Returns:

the result code

setResultCode

void setResultCode(String resultCode)

Sets the result code, possibly overriding the one returned by the action.

The "intended" purpose of this method is to allow PreResultListeners to override the result code returned by the Action.

If this method is used before the Action executes, the Action's returned result code will override what was set. However the Action could (if specifically coded to do so) inspect the ActionInvocation to see that someone "upstream" (e.g. an Interceptor) had suggested a value as the result, and it could therefore return the same value itself.

If this method is called between the Action execution and the Result execution, then the value set here will override the result code the action had returned. Creating an Interceptor that implements PreResultListener will give you this opportunity.

If this method is called after the Result has been executed, it will have the effect of raising an IllegalStateException.

Parameters:

resultCode - the result code.

Throws:

IllegalStateException - if called after the Result has been executed.

See Also:

isExecuted()

getStack

ValueStack getStack()

Gets the ValueStack associated with this ActionInvocation.

Returns:

the ValueStack

addPreResultListener

void addPreResultListener(PreResultListener listener)

Register a PreResultListener to be notified after the Action is executed and before the Result is executed.

The ActionInvocation implementation must guarantee that listeners will be called in the order in which they are registered.

Listener registration and execution does not need to be thread-safe.

Parameters:

listener - the listener to add.

invoke

String invoke()
       throws Exception

Invokes the next step in processing this ActionInvocation.

If there are more Interceptors, this will call the next one. If Interceptors choose not to short-circuit ActionInvocation processing and return their own return code, they will call invoke() to allow the next Interceptor to execute. If there are no more Interceptors to be applied, the Action is executed. If the ActionProxy.getExecuteResult() method returns true, the Result is also executed.

Returns:

the return code.

Throws:

Exception - can be thrown.

invokeActionOnly

String invokeActionOnly()
                 throws Exception

Invokes only the Action (not Interceptors or Results).

This is useful in rare situations where advanced usage with the interceptor/action/result workflow is being manipulated for certain functionality.

Returns:

the return code.

Throws:

Exception - can be thrown.

setActionEventListener

void setActionEventListener(ActionEventListener listener)

Sets the action event listener to respond to key action events.

Parameters:

listener - the listener.

init

void init(ActionProxy proxy)