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深入struts2.0(七)--ActionInvocation接口以及3DefaultActionInvocation类

2024-07-09 11:27:45   222人阅读

1.1.1       ActionInvocation类

ActionInvocation定义为一个接口，主要作用是表现action的执行状态。它拥有拦截器和action的实例。通过反复的执行invoke方法。首先被actionProxy,然后是拦截器，所有拦截器执行完后就是action和result .

图3.3.4 ActionInvocation类的主要方法

1.1.2       DefaultActionInvocation类

DefaultActionInvocation类是ActionInvocation接口的实现类. 一般都用该类实例化ActionInvocation。 主要的方法如下：

 

图3.3.5 DefaultActionInvocation类的主要方法

关键方法：invoke（）方法

executed = false; 默认为false，表示该action还没有执行。 如果执行就会抛出已经执行的异常。

然后判断拦截器是否已经配置，如果配置了拦截器就会从配置信息中获得拦截器配置类InterceptorMapping。此类中只包含两个属性，一个就是name和interceptor实例。

 

public String invoke() throws Exception {

        String profileKey = "invoke: ";

        try {

            UtilTimerStack.push(profileKey);

            if (executed) {

                throw new IllegalStateException("Action has already executed");

            }

            //递归执行interceptor

            if (interceptors.hasNext())

{          //interceptors是InterceptorMapping实际上是像一个像//FilterChain一样的Interceptor链    

            //通过调用Invocation.invoke()实现递归牡循环 

                final InterceptorMapping interceptor =interceptors.next();

                String interceptorMsg = "interceptor: " + interceptor.getName();

                UtilTimerStack.push(interceptorMsg);

                try {

//在每个Interceptor的方法中都会return invocation.invoke()                               

  resultCode = interceptor.getInterceptor().intercept(DefaultActionInvocation.this);

                            }

                finally {

                    UtilTimerStack.pop(interceptorMsg);

                }

            } else {

//当所有interceptor都执行完,最后执行Action,invokeActionOnly会调用//invokeAction()方法

                resultCode = invokeActionOnly();

            }

 

  // this is needed because the result will be executed, then control will return to the Interceptor, which will

            // return above and flow through again

   //在Result返回之前调用preResultListeners     

        //通过executed控制,只执行一次 

            if (!executed) {

                if (preResultListeners !=null) {

                    for (Object preResultListener :preResultListeners) {

                        PreResultListener listener = (PreResultListener) preResultListener;

 

                        String _profileKey = "preResultListener: ";

                        try {

                            UtilTimerStack.push(_profileKey);

                            listener.beforeResult(this,resultCode);

                        }

                        finally {

                            UtilTimerStack.pop(_profileKey);

                        }

                    }

                }

                // now execute the result, if we‘re supposed to

//执行result。

                if (proxy.getExecuteResult()) {

                    executeResult();

                }

                executed = true;

            }

            return resultCode;

        }

        finally {

            UtilTimerStack.pop(profileKey);

        }

    }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

  


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