ajax验证用户名是否存在

js代码

function validatorloginName(){  

    var loginName=document.getElementById("suser").value; 

    var reg=new RegExp("^[a-zA-Z]{1}[a-zA-Z0-9]{5,11}$");

    if(loginName == "")  

    {  $("input[name='sname']").next().removeClass("ok");

       $("input[name='sname']").next().html("用户名不能为空!");

       $("input[name='sname']").next().addClass("err");  

       return;  

    }  

    else if(!reg.exec(loginName)){

        $("input[name='sname']").next().removeClass("ok");

        $("input[name='sname']").next().html("用户名格式错误,首位必须是字母长度不能小于六位!");

        $("input[name='sname']").next().addClass("err");

        return false;

    }else{

        $("input[name='sname']").next().html("");

         $.ajax({  

               type: "POST",      

                url: "../servlet/ValidateName",      

                 data: "loginName="+loginName,   

                success: function(data){  

               if(data=="true"){ 

                   $("input[name='sname']").next().html("");

                   $("input[name='sname']").next().addClass("ok");

                   return true;

                

               }else{ 

                   $("input[name='sname']").next().removeClass("ok");

                   $("input[name='sname']").next().html("抱歉！用户名已存在！");

                   $("input[name='sname']").next().addClass("err");

                   return false;

               }   

               }            

               });     

        

    }

}

web.xml配置

  <servlet>

  <servlet-name>ValidateName</servlet-name>

    <servlet-class>Util.ValidateName</servlet-class>

  </servlet>

  <servlet-mapping>

    <servlet-name>ValidateName</servlet-name>

    <url-pattern>/servlet/ValidateName</url-pattern>

  </servlet-mapping>

java代码

package Util;

import java.io.IOException;

import java.io.PrintWriter;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;



import javax.naming.Context;

import javax.naming.InitialContext;

import javax.naming.NamingException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.sql.DataSource;





public class ValidateName extends HttpServlet {

    public ValidateName(){

        super();

    }



    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {



        response.setContentType("text/html");

        String loginName=request.getParameter("loginName").toString();

    

        try {

            Context ctx = new InitialContext();

            DataSource    ds = (DataSource)ctx.lookup("java:/comp/env/jdbc/oracle");

            Connection conn = ds.getConnection();

            PreparedStatement pst = conn.prepareStatement("select * from huiyuan where suser='"+loginName+"' ");

            ResultSet res=pst.executeQuery();

            boolean flog=res.next();

            if(!flog){

            response.getWriter().write("true");//此值jquery可以接收到  

            }

        } catch (NamingException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

        

        }



    

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {



        this.doGet(request, response); 

        

    }



}