JSP中用Ajax

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前台

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><TITLE>留学生系统</TITLE><META http-equiv=Content-Type content="text/html; charset=GBK"><SCRIPT language=JavaScript type=text/JavaScript>var XMLHttpReq = false;function createXMLHttpRequest(){    if(window.XMLHttpRequest){       XMLHttpReq = new XMLHttpRequest();    }else if(window.ActiveXObject){       try{           XMLHttpReq = new ActiveXObject("MSXML2.XMLHTTP");       }catch(e){           try{              XMLHttpReq = new ActiveXObject("Mircsoft.XMLHTTP");           }catch(e1){}       }    }}function sendRequest(url){    createXMLHttpRequest();    XMLHttpReq.open("GET",url,true);    XMLHttpReq.onreadystatechange = processResponse;    XMLHttpReq.send(null);}function processResponse(){    if(XMLHttpReq.readyState == 4){       if(XMLHttpReq.status == 200){           var res = XMLHttpReq.responseXML.getElementsByTagName("res")[0].firstChild.data;           window.alert(res);           document.myform.userid.value="";           document.myform.pwd.value="";       }else{           window.alert("你请求的页面有异常1");       }    }}function userCheck(){    var userid = document.myform.userid.value;    var pwd = document.myform.pwd.value;    if(userid == ""){       window.alert("用户名不能为空");       document.myform.pwd.value="";       document.myform.userid.focus();       return false;    }else{       sendRequest("login?userid="+userid);    }}function pwdCheck(){    var pwd = document.myform.pwd.value;    var pwd2 = document.myform.pwd2.value;    if(pwd!=pwd2){       window.alert("密码不一致");       document.myform.pwd.value="";       document.myform.pwd2.value="";       document.myform.pwd.focus();       return false;    }}</SCRIPT><LINK href="css/css.css" type=text/css rel=stylesheet></HEAD>    <body>  <table width="778" border="0" align="center" cellpadding="0" cellspacing="0" bgcolor="#FFFFFF" >  <tr>    <td width="17%"><img src="images/logo.jpg" width="124" height="101"></td>    <td width="558" height="101" background="images/banner.jpg"><div align="center">        <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,29,0" width="558" height="101">          <param name="movie" value="images/2.swf">          <param name="quality" value="high">          <embed src="images/2.swf" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" width="558" height="101"></embed>          <param name="wmode" value="transparent">        </object>    </div></td>    <td width="11%"><table width="100%" border="0" cellpadding="0" cellspacing="0" >        <tr>          <td height="30" class="style1"><div align="center">设为首页</div></td>        </tr>        <tr>          <td height="30" class="style1"><div align="center">收藏本站</div></td>        </tr>        <tr>          <td height="30" class="style1"><div align="center">联系我们</div></td>        </tr>    </table></td>  </tr></table>    <form method="post" action="control.jsp?action=register" name="myform">    <table width="300" border="0" align="center" bgcolor="#F0F0F0">        <tr>            <td align="center">用户名</td>            <td><input name="userid" type="text" size="20" onblur="userCheck()"></td>        </tr>        <tr>            <td align="center">真实姓名</td>            <td><input name="username" type="text" size="20"/></td>        </tr>        <tr>            <td align="center">性别</td>            <td>              <input type="radio" name="sex" value="0" checked="checked">男               <input type="radio" name="sex" value="1">女            </td>        </tr>        <tr>            <td align="center">密码</td>            <td><input name="pwd" type="password" size="20"/></td>        </tr>        <tr>            <td align="center">密码确认</td>            <td><input name="pwd2" type="password" size="20" onblur="pwdCheck()"/></td>        </tr>        <tr>            <td align="center">电子邮箱</td>            <td><input name="email" type="text" size="20"/></td>        </tr>        <tr>            <td align="center">学校</td>            <td><input name="school" type="text" size="20"/></td>        </tr>        <tr>            <td align="center">电话号码</td>            <td><input name="phonenum" type="text" size="20"/></td>        </tr>        <tr>            <td align="center"><img border=0 src="image.jsp"></td>            <td><input type=text name=in maxlength=4 size="8"></td>         </tr>                <tr>            <td align="center"><input type="submit" value="确定" /></td>        </tr>    </table>    </form>  </body></html>

后台连接MySql数据库

DB.java

package com.common;import java.sql.Connection;import java.sql.SQLException;import javax.naming.InitialContext;import javax.sql.DataSource;public class DBConfig{  public static boolean inited = false;  public static DataSource ds = null;  public static void Init()  {    InitialContext localInitialContext;    try    {      localInitialContext = new InitialContext();      ds = (DataSource)localInitialContext.lookup("java:/comp/env/jdbc/saDB");      inited = true;    }    catch (Exception exception)    {      System.err.println("DBConfig (): " + exception.getMessage());      exception.printStackTrace();    }  }  public static Connection getConn()  {    if (!(inited))      Init();    try    {      return ds.getConnection();    }    catch (SQLException localSQLException)    {      System.err.println("getConn ():" + localSQLException.getMessage());      localSQLException.printStackTrace(System.err);      Init();    }    return null;  }}

接受request和回应response

LoginAction.java

package com.common;import java.io.IOException;import java.io.PrintWriter;import java.sql.ResultSet;import java.sql.SQLException;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginAction extends HttpServlet {       @Override       protected void doGet(HttpServletRequest req, HttpServletResponse resp)                     throws ServletException, IOException {              // TODO Auto-generated method stub              req.setCharacterEncoding("UTF-8");              String userid = req.getParameter("userid");              resp.setContentType("text/xml;charset=UTF-8");              resp.setHeader("Cache-Control", "no-cache");              PrintWriter out = resp.getWriter();              out.println("<response>");              DB db = new DB();              ResultSet rs;              String strSql = null;              strSql = "select * from users where user_id='" + userid + "';";              rs = db.executeQuery(strSql);              try{                     if(rs.next()){                            out.println("<res>" + "用户名已存在" + "</res>");                     }else{                            out.println("<res></res>");                     }              }catch(SQLException e){                     e.printStackTrace();              }              out.println("</response>");              out.close();       }       @Override       protected void doPost(HttpServletRequest req, HttpServletResponse resp)                     throws ServletException, IOException {              // TODO Auto-generated method stub              super.doGet(req, resp);       }       @Override       public void init(ServletConfig config) throws ServletException {              // TODO Auto-generated method stub       }} 

转自：http://www.cnblogs.com/xchaos/archive/2012/02/26/2369168.html

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