XMLHttpRequest 对象相关

XMLHttpRequest 对象用于在后台与服务器交换数据。

后台

package com.java1234.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;

import net.sf.json.JSONArray;

import net.sf.json.JSONObject;

public class GetAjaxInfoServlet extends HttpServlet{

    /**

     *

     */

    private static final long serialVersionUID = 1L;

    @Override

    protected void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        this.doPost(request, response);

    }

    @Override

    protected void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        response.setContentType("text/html;charset=utf-8");

        String action=request.getParameter("action");

        if("checkUserName".equals(action)){

            this.checkUserName(request, response);

        }else if("ejld".equals(action)){

            this.ejld(request, response);

        }

    }

    private void checkUserName(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        PrintWriter out=response.getWriter();

        String userName=request.getParameter("userName");

        JSONObject resultJson=new JSONObject();

        if("jack".equals(userName)){

            resultJson.put("exist", true);

        }else{

            resultJson.put("exist", false);

        }

        out.println(resultJson);

        out.flush();

        out.close();

    }

    private void ejld(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        PrintWriter out=response.getWriter();

        String shengId=request.getParameter("shengId");

        JSONObject resultJson=new JSONObject();

        JSONArray jsonArray=new JSONArray();

        JSONObject temp=null;

        switch(Integer.parseInt(shengId)){

            case 1:{

                temp=new JSONObject();temp.put("id", 1);temp.put("text", "南京");jsonArray.add(temp);

                temp=new JSONObject();temp.put("id", 2);temp.put("text", "南通");jsonArray.add(temp);

                temp=new JSONObject();temp.put("id", 3);temp.put("text", "泰兴");jsonArray.add(temp);

                break;

            }

            case 2:{

                temp=new JSONObject();temp.put("id", 4);temp.put("text", "济南");jsonArray.add(temp);

                temp=new JSONObject();temp.put("id", 5);temp.put("text", "烟台");jsonArray.add(temp);

                temp=new JSONObject();temp.put("id", 6);temp.put("text", "蓬莱");jsonArray.add(temp);

                break;

            }

            case 3:{

                temp=new JSONObject();temp.put("id", 7);temp.put("text", "杭州");jsonArray.add(temp);

                temp=new JSONObject();temp.put("id", 8);temp.put("text", "宁波");jsonArray.add(temp);

                temp=new JSONObject();temp.put("id", 9);temp.put("text", "温州");jsonArray.add(temp);

                break;

            }

        }

        resultJson.put("rows", jsonArray);

        out.println(resultJson);

        out.flush();

        out.close();

    }

}

首页

<%@ 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>My JSP 'insex.jsp' starting page</title>

    <!-- 控制缓存 -->

    <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>

    <br/>

    <br/>

    <br/>

    <a href="ejld.jsp">二级联动</a>

    <br/>

    <br/>

    <br/>

    <a href="checkUserName.jsp">ajax&json验证</a>

  </body>

</html>

验证姓名是否存在

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

<script type="text/javascript">

    function checkUserName(){

        var userName=document.getElementById("userName").value;

        var xmlHttp;

        if(window.XMLHttpRequest){

            xmlHttp=new XMLHttpRequest();

        }else{

            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");

        }

        xmlHttp.onreadystatechange=function(){

            if(xmlHttp.readyState==4 && xmlHttp.status==200){

                alert(xmlHttp.responseText);

                var dataObj=eval("("+xmlHttp.responseText+")");

                if(dataObj.exist){

                    document.getElementById("tip").innerHTML="<img src='no.png'/>&nbsp;该用户名已经存在";

                }else{

                    document.getElementById("tip").innerHTML="<img src='ok.png'/>&nbsp;该用户名可用";

                }

            }

        };

        xmlHttp.open("get", "getAjaxInfo?action=checkUserName&userName="+userName, true);

        xmlHttp.send();

    }

</script>

</head>

<body>

<table>

    <tr>

        <th>用户注册</th>

    </tr>

    <tr>

        <td>用户名：</td>

        <td><input type="text" id="userName" name="userName" onblur="checkUserName()"/>&nbsp;&nbsp;<font id="tip"></font></td>

    </tr>

    <tr>

        <td>密码：</td>

        <td><input type="text" id="password" name="password"/></td>

    </tr>

    <tr>

        <td>确认密码：</td>

        <td><input type="text" id="password2" name="password2"/></td>

    </tr>

    <tr>

        <td><input type="submit" value="注册"/></td>

        <td><input type="button" value="重置"/></td>

    </tr>

</table>

</body>

</html>

二级联动

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

<script type="text/javascript">

    function loadInfo(){

        var shengId=document.getElementById("sheng").value;

        shi.options.length=0;  // 删除所有市下拉框的选项

        var xmlHttp;

        if(window.XMLHttpRequest){

            xmlHttp=new XMLHttpRequest();

        }else{

            xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");

        }

        xmlHttp.onreadystatechange=function(){

            if(xmlHttp.readyState==4 && xmlHttp.status==200){

                //alert(xmlHttp.responseText);

                var dataObj=eval("("+xmlHttp.responseText+")");

                for(var i=0;i<dataObj.rows.length;i++){

                    var o=dataObj.rows[i];

                    shi.options.add(new Option(o.text,o.id));

                }

            }

        };

        xmlHttp.open("get", "getAjaxInfo?action=ejld&shengId="+shengId, true);

        xmlHttp.send();

    }

</script>

</head>

<body>

省：

<select id="sheng" onchange="loadInfo()">

    <option value="1">江苏省</option>

    <option value="2">山东省</option>

    <option value="3">浙江省</option>

</select>

&nbsp;&nbsp;

市：

<select id="shi">

</select>

</body>

</html>

巴特西

XMLHttpRequest 对象相关

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