servlet与jsp交互问题

来源：互联网发布：suse网络配置编辑：程序博客网时间：2024/05/16 05:14

最近一直困扰我的一个问题：
问题描述：
在jsp页面使用ajax返回数据时，后台的servlet一直取不到数据。(userid一直为空)
index.jsp页面：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><html><head><!-- meta使用viewport以确保页面可自由缩放 --><meta name="viewport" content="width=device-width, initial-scale=1"><!-- 引入 jQuery Mobile 样式 --><link rel="stylesheet"    href="http://code.jquery.com/mobile/1.4.5/jquery.mobile-1.4.5.min.css"><!-- 引入 jQuery 库 --><script src="http://code.jquery.com/jquery-1.11.3.min.js"></script><!-- 引入 jQuery Mobile 库 --><script    src="http://code.jquery.com/mobile/1.4.5/jquery.mobile-1.4.5.min.js"></script><script type="text/javascript">        (function ($) {              //扩展方法获取url参数              $.getUrlParam = function (name) {                  var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)");                  var r = window.location.search.substr(1).match(reg);                  if (r != null) return unescape(r[2]); return null;              };        })(jQuery);            //得到url参数                var userid = $.getUrlParam('userid');            alert(userid);            //ajax            var options = {                      url: "${pageContext.request.contextPath}/servlet/UserMsgServlet",                      type: "GET",                                          dataType: "String",                                          data:userid ,                      async:true,                     success: function (data) {                          alert(data.detail);                      }                  };                 $.ajax(options);    </script><script type="text/javascript">/*  $("#panelButton").click(function(){                 $.getUrlParam = function (name) {                  var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)");                  var r = window.location.search.substr(1).match(reg);                  if (r != null) return unescape(r[2]); return null;              };        })(jQuery);        var userid = $.getUrlParam('userid');        $.ajax({                url:'${pageContext.request.contextPath}/servlet/UserMsgServlet',                type:'get',                async:true,                data:{userid:userid},                datatype:'text/json',                success:function(data){                    $("#myPanels").append("p"+data+"</p>");                }                });    }); */</script></head><body>    <div data-role="page" id="pageone">        <!-- 面板内容 -->        <div data-role="panel" id="myPanels">        <ul data-role="listview">                <li><a href="#">列表项</a></li>                <li><a href="#">列表项</a></li>        </ul>        </div>        <!-- 头部 -->        <div data-role="header">            <!--头部功能-->            <div class="ui-grid-a">                    <div class="ui-block-a">                        <a id="panelButton" href="#myPanels"   data-role="button" data-inline="true" data-icon="bars"  >面板</a>                    </div>                <div class="ui-block-b" style="text-align:right">                    <a id="Search" href="${pageContext.request.contextPath }/servlet/UserMsgServlet" data-role="button" data-icon="Search">获取用户</a>                </div>                <!-- <div class="ui-block-c">                    <input type="search" name="search" id="search"                        placeholder="搜索内容...">                </div> -->            </div>        </div>        <!-- 中部 -->        <div id= "middle "data-role="main" class="ui-content"></div>        <!-- 底部 -->        <div data-role="footer" style="text-align:center " data-position="fixed">         <div data-role="navbar" data-iconpos="bottom">         <ul>             <li><a href="#"  data-role="button"  data-icon="info" >收件箱</a></li>             <li><a href="#"  data-role="button"   data-icon="grid"  >待阅</a></li>             <li><a href="#"  data-role="button"   data-icon="star" >待办</a></li>         </ul>        </div>        </div>    </div></body></html>

UserMsgservlet的代码如下：

package oa.webservice.web;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import oa.webservice.test.ClientTest1;public class UserMsgServlet extends HttpServlet {    /**     * The doGet method of the servlet. <br>     *     * This method is called when a form has its tag value method equals to get.     *      * @param request the request send by the client to the server     * @param response the response send by the server to the client     * @throws ServletException if an error occurred     * @throws IOException if an error occurred     */    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("application/json,charse=utf-8");        String userid = request.getParameter("userid");        System.out.println(userid);        String userName = ClientTest1.getClientTest1().oa_IsUserExist();        request.setAttribute("userName", userName);        request.getRequestDispatcher("/index.jsp").forward(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

先记录下来看看能不能解决。
知识点：ajax,servlet的作用域。

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