JS实现AJAX提交数据到后台,实现验证用户名是否存在功能详解

来源：互联网发布：mac误删除文件恢复编辑：程序博客网时间：2024/05/20 06:26

ajaxmanul.js代码如下:

checkUserAjax.html代码如下:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
      <title>My JSP 'checkUser starting page</title>

   <meta http-equiv="pragma" content="no-cache">
   <meta http-equiv="cache-control" content="no-cache">
   <meta http-equiv="expires" content="0">
   <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
   <meta http-equiv="description" content="This is my page">
   <script type="text/javascript" src="js/ajaxmanul.js" ></script>
</head>

<body>
    <center>
       <br />
       用户名:<input type="text" id="userName" />
       <input type="button" value="校验" onclick="validate()" />
       <div id="showResult"></div>
    </center>
</body>
</html>

后台(CheckUserName.java)servlet代码如下:

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CheckUserName extends HttpServlet {


   public void doGet(HttpServletRequest request, HttpServletResponse response)
           throws ServletException, IOException {
       //HttpServletResponse.setContentType("text/html:charset=utf-8");
       request.setCharacterEncoding("utf-8");
       response.setCharacterEncoding("utf-8");
       PrintWriter out=response.getWriter();
       //获取页面参数
       String userName=request.getParameter("userName");
       //检测参数是否与DB中相应数据相匹配
       if(userName==null||userName.length()==0){
           out.println("用户名不能为空");
       }else{
           //校验操作
           if(userName.equals("tfq")){
               //返回页面数据
               out.println("用户名已经存在");
           }else{
               out.println("恭喜你!此用户可用");
           }
       }

   }

}

以上代码绝对能实现验证用户名是否存在功能。