Jsp属性范围

IDE:MyEclipse 2014(自带Tomcat 7)

Web项目路径：

Web项目配置信息：

WebRoot

　　--WEB-INF

　　　　--web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>MyPro02</display-name>

  <servlet>
    <servlet-name>MyServlet</servlet-name>
    <servlet-class>com.zhiyuan.web.MyServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>MultiMappingServlet</servlet-name>
    <servlet-class>com.zhiyuan.web.MultiMappingServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>MyServlet</servlet-name>
    <url-pattern>/servlet/MyServlet</url-pattern>
  </servlet-mapping>

 <!--  一个Servlet映射多个Mapping -->
  <servlet-mapping>
    <servlet-name>MultiMappingServlet</servlet-name>
    <url-pattern>/admin/multiMappingServlet.do</url-pattern>
    <url-pattern>/user/multiMappingServlet.do</url-pattern>
  </servlet-mapping>

  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>

</web-app>

　　admin

　　　　--index.jsp

<%@ page language="java" import="java.util.*" 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>管理员角色</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">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>

  <body>
      <%request.setAttribute("jiaose", "admin");// 服务端跳转
      request.getRequestDispatcher("multiMappingServlet.do").forward(request, response);
       %>
  </body>
</html>

src

　　--com.zhiyuan.web

　　　　--MultiMappingServlet.java

 package com.zhiyuan.web;
 import java.io.IOException;
 import java.io.PrintWriter;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 public class MultiMappingServlet extends HttpServlet {

     /**
      * 串行号
      */
     private static final long serialVersionUID = 7091664030094770793L;
     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         this.doPost(request, response);
     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         response.setCharacterEncoding("gbk");
         PrintWriter pw=response.getWriter();
         pw.write("角色管理:");
         String jiaose=(String) request.getAttribute("jiaose");
         if ("admin".equals(jiaose)) {
             pw.write("管理员");
         }else if ("user".equals(jiaose)) {
             pw.write("用户");
         }
     }

 }

MultiMappingServlet

Web项目运行结果：

注意：如果使用了下面的跳转形式：

<%@ page language="java" import="java.util.*" 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>管理员角色</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">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>

  <body>
      <%
    　　request.setAttribute("jiaose", "admin");
       %>
    <a href="multiMappingServlet.do">管理员角色</a>
  </body>
</html>

或者

<%@ page language="java" import="java.util.*" 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>管理员角色</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">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>

  <body>
      <%
      request.setAttribute("jiaose", "admin");
      // 重定向(客户端跳转)
      response.sendRedirect("multiMappingServlet.do");
       %>
  </body>
</html>

MultiMappingServlet.java代码不变的情况下，

发现Web项目启动时，地址栏改变了，设置的属性也消失了。

如果希望无论怎样跳转，属性都可以被保存下来，可以扩大到session范围。

修改后的代码：

<%@ page language="java" import="java.util.*" 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>管理员角色</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">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>

  <body>
      <%
      pageContext.setAttribute("jiaose", "admin", pageContext.SESSION_SCOPE);
      // 重定向(客户端跳转)
      response.sendRedirect("multiMappingServlet.do");
       %>
  </body>
</html>

或者

<%@ page language="java" import="java.util.*" 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>管理员角色</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">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->

  </head>

  <body>
      <%
      pageContext.setAttribute("jiaose", "admin", pageContext.SESSION_SCOPE);
       %>
    <a href="multiMappingServlet.do">管理员角色</a>
  </body>
</html>

MultiMappingServlet.java的代码：

 package com.zhiyuan.web;
 import java.io.IOException;
 import java.io.PrintWriter;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 public class MultiMappingServlet extends HttpServlet {

     /**
      * 串行号
      */
     private static final long serialVersionUID = 7091664030094770793L;
     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         this.doPost(request, response);
     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         response.setCharacterEncoding("gbk");
         PrintWriter pw=response.getWriter();
         pw.write("角色管理:");
         String jiaose=(String) request.getSession().getAttribute("jiaose");
         if ("admin".equals(jiaose)) {
             pw.write("管理员");
         }else if ("user".equals(jiaose)) {
             pw.write("用户");
         }
     }

 }

MultiMappingServlet

巴特西

Jsp属性范围

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