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);

}

}