【图】简单的ajax+servlet表单数据验证

一、用户注册的JSP页面

%@ page contentType="text/html;charset=UTF-8" language="java" %
head
META http-equiv=Content-Type content="text/html; charset=UTF-8"
/head
script language="javascript"

 var XMLHttpReq;  //创建XMLHttpRequest对象   function createXMLHttpRequest() {  if(window.XMLHttpRequest) { //Mozilla 浏览器   XMLHttpReq = new XMLHttpRequest();  }  else if (window.ActiveXObject) { // IE浏览器   try {XMLHttpReq = new ActiveXObject("Msxml2.XMLHTTP");   } catch (e) {try { XMLHttpReq = new ActiveXObject("Microsoft.XMLHTTP");} catch (e) {}   }  } } //发送请求函数 function sendRequest(url) {  createXMLHttpRequest();  XMLHttpReq.open("GET", url, true);  XMLHttpReq.onreadystatechange = processResponse;//指定响应函数  XMLHttpReq.send(null);  // 发送请求 } // 处理返回信息函数function processResponse() { if (XMLHttpReq.readyState == 4) { // 判断对象状态 if (XMLHttpReq.status == 200) { // 信息已经成功返回，开始处理信息 var res=XMLHttpReq.responseXML.getElementsByTagName("res")[0].firstChild.data;  window.alert(res); } else { //页面不正常  window.alert("您所请求的页面有异常。");}}} // 注册函数function signUp() {  var uname = document.myform.uname.value;  var psw = document.myform.psw.value;  var psw2 = document.myform.psw2.value;  if(uname=="") {   window.alert("用户名不能为空。");   document.myform.uname.focus();   return false;  }  else if(psw!=psw2) {   window.alert("两次输入密码不同。");   document.myform.psw.focus();   return false;  }  else {   sendRequest('signUp？uname='+ uname + '&psw=' + psw);  } }/script

body vLink="#006666" link="#003366" bgColor="#E0F0F8"
  img height="33" src="enter.gif" width="148"
  form action="" method="post" name="myform"
    用户名： input size="15" name="uname"p
    密  码： input type="password" size="15" name="psw"p
    重输密码： input type="password" size="20" name="psw2"p
    input type="button" value="注册" onclick="signUp()"
  /form

/body

运行图：

二、处理AJAX请求的servlet

package classmate;
import java.io.IOException;
import java.io.PrintWriter;

ntln("res" + "注册失败！" + "/res");
  }

  out.println("/response");
  out.close();
    }
}

三、数据库操作类：

package classmate;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DB {
Connection connect = null;
ResultSet rs = null;
public DB() {
  try {
   Class.forName("org.gjt.mm.mysql.Driver"); //设置驱动程序类型
  }
  catch(java.lang.ClassNotFoundException e) {
   e.printStackTrace();
  }
}
//执行查询语句的方法
public ResultSet executeQuery(String sql) {
  try {
//建立与数据库服务器的连接
     onnect = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test1", "root", "");br     tatement stmt = connect.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
   rs = stmt.executeQuery(sql);//执行指定的数据查询语句
  }
  catch(SQLException ex) {
   ex.printStackTrace();
  }
  return rs;
}
    //执行增、删改语句的方法
public int executeUpdate(String sql) {
  int result = 0;
  try {
   connect = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/test1", "root", "");
   Statement stmt = connect.createStatement();
   result = stmt.executeUpdate(sql);//执行指定的数据操作语句
  }
  catch(SQLException ex) {
   System.err.println(ex.getMessage());
  }
  return result;
}
//关闭数据库连接的方法
public void close(){
  if(connect!=null){
   try{
    connect.close();
    connect = null;
   }catch(SQLException ex) {
    System.err.println(ex.getMessage());
   }
  }
}

}

四、web.xml文件中配置servlet

？xml version="1.0" encoding="UTF-8"？
web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"

servlet
servlet-namems1/servlet-name
servlet-classclassmate.SignUpAction/servlet-class
/servlet

servlet-mapping
servlet-namems1/servlet-name
url-pattern/signUp/url-pattern
/servlet-mapping

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 SignUpAction extends HttpServlet {
   public void init(ServletConfig config) throws ServletException {
}
    /*
     * 处理GET 请求方法.
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    //设置接收信息的字符集
    request.setCharacterEncoding("UTF-8");
    //接收浏览器端提交的信息
  String uname = request.getParameter("uname");
  String psw = request.getParameter("psw");
  //设置输出信息的格式及字符集
        response.setContentType("text/xml; charset=UTF-8");
        response.setHeader("Cache-Control", "no-cache");
        //创建输出流对象
        PrintWriter out = response.getWriter();
        //依据验证结果输出不同的数据信息
        out.println("response");

        //数据库操作
        DB db = new DB();
  ResultSet rs;
  int insRes = 0;
        String strSql=null;
        //判断用户名是否重复
        strSql = "select * from classuser where username='"
   + uname + "'";
  rs = db.executeQuery(strSql);
  boolean bnoRepeat = false;
  try {
   if ( !rs.next()) {
    bnoRepeat = true;
   }
  } catch (SQLException e) {
   e.printStackTrace();
  }
        //用户名不重复,插入记录
  if (bnoRepeat){
            strSql = "Insert Into classuser values('"+ uname + "','" + psw + "')";
   insRes = db. executeUpdate(strSql);
        }
        if(!bnoRepeat){
   out.println("res" + "注册失败!用户名已存在，重新输入用户名" + "/res");
  }else if(insRes0){
   out.println("res" + "注册成功！" + "/res");
  }else{
   out.pri