ActionDispatcher 辅助类学习

ActionDispatcher

是行动 辅助类，在一个行动调度到一个公共方法。   .这个类是作为一种替代机制，使用DispatchAction及其各种口味和手段， 调度行为可以很容易地提供到任何Action执行，而不必从一个特定的继承超级Action 。实例Action 持有该类的对象，可以根据参数的不同，实现和MappingDispatcherAction、DispatchAction的类似的功能。

实现代码

             protected ActionDispatcher dispatcher
                                = new ActionDispatcher( this, ActionDispatcher.MAPPING_FLAVOR);

             public ActionForward execute(ActionMapping mapping,
                                                                        ActionForm form,
                                                                        HttpServletRequest request,
                                                                        HttpServletResponse response)
                                                     throws Exception {
                     return dispatcher.execute(mapping, form, request, response);
             }

 

new ActionDispatcher(this, ActionDispatcher.MAPPING_FLAVOR) 的时候，可以根据实际需要，指定不同的MAPPING_FLAVOR，实现不同类型的Action功能。

包含：

DEFAULT_FLAVOR

DISPATCH_FLAVOR

MAPPING_FLAVOR

 

1.Struts-config.xml

                <action path= "/actionDispatcher-submit"    
                                type= "org.apache.struts.webapp.dispatch.ActionDispatcherExample"
                                parameter= "actionDispatcherMethod"
                                name= "testForm"
                                scope= "request">
                        <exception key= "dispatch.NoSuchMethodException"
                                             type= "java.lang.NoSuchMethodException"
                                             path= "/actionDispatcher.jsp"/>
                        <exception key= "dispatch.ServletException"
                                             type= "javax.servlet.ServletException"
                                             path= "/actionDispatcher.jsp"/>
                        <forward name= "success" path= "/actionDispatcher.jsp"/>
                </action>

 

这里的parameter="actionDispatcherMethod" 与DispatcherAction 意义相同

 

2.Action代码 也与DispatcherAction 例子中代码一致。只多了以下代码

     private ActionDispatcher dispatcher
                                        = new ActionDispatcher( this,
                                                                ActionDispatcher.DISPATCH_FLAVOR);
         public ActionForward execute(ActionMapping mapping,
                                                                 ActionForm form,
                                                                 HttpServletRequest request,
                                                                 HttpServletResponse response)
                 throws Exception {
                 return dispatcher.execute(mapping, form, request, response);

        }

 

 

如果没有execute()方法，会出现空白页页面。

 

1.出现的异常也和LookupDispatcherAction、MappingDispatcherAction 一样。