org.apache.struts2.ActionInvocation Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.struts2;
import org.apache.struts2.action.Action;
import org.apache.struts2.interceptor.PreResultListener;
import org.apache.struts2.result.ActionChainResult;
import org.apache.struts2.result.Result;
import org.apache.struts2.util.ValueStack;
/**
* An {@link ActionInvocation} represents the execution state of an {@link Action}. It holds the Interceptors and the Action instance.
* By repeated re-entrant execution of the invoke() method, initially by the {@link ActionProxy}, then by the Interceptors, the
* Interceptors are all executed, and then the {@link Action} and the {@link Result}.
*
* @author Jason Carreira
* @see ActionProxy
*/
public interface ActionInvocation {
/**
* Get the Action associated with this ActionInvocation.
*
* @return the Action
*/
Object getAction();
/**
* Gets whether this ActionInvocation has executed before.
* This will be set after the Action and the Result have executed.
*
* @return true if this ActionInvocation has executed before.
*/
boolean isExecuted();
/**
* 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.
*
* @return the ActionContext.
*/
ActionContext getInvocationContext();
/**
* Get the ActionProxy holding this ActionInvocation.
*
* @return the ActionProxy.
*/
ActionProxy getProxy();
/**
* If the ActionInvocation has been executed before and the Result is an instance of {@link 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.
*
* @return the result.
* @throws Exception can be thrown.
*/
Result getResult() throws Exception;
/**
* Gets the result code returned from this ActionInvocation.
*
* @return the result code
*/
String getResultCode();
/**
* 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
* {@link 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.
*
*
* @param resultCode the result code.
* @throws IllegalStateException if called after the Result has been executed.
* @see #isExecuted()
*/
void setResultCode(String resultCode);
/**
* Gets the ValueStack associated with this ActionInvocation.
*
* @return the ValueStack
*/
ValueStack getStack();
/**
* Register a {@link 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.
*
*
* @param listener the listener to add.
*/
void addPreResultListener(PreResultListener listener);
/**
* 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 {@link ActionProxy#getExecuteResult()} method returns true, the Result is also executed.
*
*
* @throws Exception can be thrown.
* @return the return code.
*/
String invoke() 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.
*
*
* @return the return code.
* @throws Exception can be thrown.
*/
String invokeActionOnly() throws Exception;
/**
* Sets the action event listener to respond to key action events.
*
* @param listener the listener.
*/
void setActionEventListener(ActionEventListener listener);
void init(ActionProxy proxy);
}