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); 

    }

}