struts中的action是单态的

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一 action特性

action是单态的，包括ActionServlet。

单态是指：在整个程序运行过程中，始终是一个对象。

 

二 action单态特性证明

1  LoginAction

package com.cakin.actions;

//这是一个action（表示小队长，需要继承Action）

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;

import org.apache.struts.action.ActionForm;

import org.apache.struts.action.ActionForward;

import org.apache.struts.action.ActionMapping;

import com.cakin.forms.UserForm;

public class LoginAction extends Action {

    private int num=0;

    //我们需要重新编写一个方法：execute会被自动调用，有点类似servlet的service方法。

    @Override

    public ActionForward execute(ActionMapping mapping, ActionForm form,

            HttpServletRequest request, HttpServletResponse response)

            throws Exception {

            //把form转成对应的UserForm对象

        UserForm userForm=(UserForm)form;

        num++;

        //简单验证

        if("123".equals(userForm.getPassword())){

            //把名字存放到request对象域

            //request.setAttribute("username", userForm.getUsername());

            request.setAttribute("num",num+"");

            return mapping.findForward("ok");

        }

        else{

            return mapping.findForward("err");

        }

    }

}

 

2  wel.jsp

<%@ page language = "java" import = "java.util.*" import = "com.cakin.forms.*" pageEncoding = "utf-8" %>

<%

String path = request.getContextPath();

String basePath = request.getScheme()+ "://" +request.getServerName()+ ":" +request.getServerPort()+path+ "/" ;

%>

 

DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

< html >

  < head >

    < base href = " <%= basePath %> " >

   

    < title > My JSP 'wel.jsp' starting page title >

   

         < meta http-equiv = "pragma" content = "no-cache" >

         < meta http-equiv = "cache-control" content = "no-cache" >

         < meta http-equiv = "expires" content = "0" >    

         < meta http-equiv = "keywords" content = "keyword1,keyword2,keyword3" >

         < meta http-equiv = "description" content = "This is my page" >

        

 

  head >

 

  < body >

    welcome <%= ((UserForm)session.getAttribute( "userForm" )).getUsername() %> < br >

    < a href = "/strutslogin/" > 返回重新登录 a >

    num = <%= request.getAttribute( "num" ) %>

  body >

html >

 

三 测试结果

 

 

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