黑马day17 ajax&实现用户名自动刷新

1. regist.jsp文件

<%@ page language="java" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <title>校验用户名是否存在</title>
        <script type="text/javascript" src="./regist.js"> </script>
    </head>
    <body>
    <center>
    <form action="" enctype="application/x-www-form-urlencoded" method="post">
        <h3>请填写用户注册信息</h3>
        <table border="1">
            <tr>
                <td>用户名:</td>
                <td><input type="text" name="username" value="" id="username">
                  <div id="divcheck"></div>
                  <input type="button" name="checkusername" value="查看用户名" id="checkusername"></td>
            </tr>
            <tr>
                <td>密码:</td>
                <td><input type="password" name="psw" value=""></td>
            </tr>
            <tr>
                <td>确认密码:</td>
                <td><input type="password" name="confpsw" value=""></td>
            </tr>
            <tr>
                <td>出生日期:</td>
                <td><input type="text" name="birthday" value=""></td>
            </tr>
        </table>
         </form>
         </center>
    </body>

</html>

运行界面：

2.regist文件

window.onload=function(){
    document.getElementById("checkusername").onclick=function(){
        var username=document.getElementById("username").value;//获取text文本框中输入的值
        //1.获取xhr对象
        var xhr=ajaxFunction();
        //2.监听
        xhr.onreadystatechange=function(){
            if(xhr.readyState==4){
                if(xhr.status==200){
                    var data=xhr.responseText;
                    document.getElementById("divcheck").innerHTML=data;
                }
            }
        }
        //3.建立连接
        xhr.open("post","../servlet/ValidateUsernameServlet");
        //4.发送数据
        //如果请求类型是POST方式的话,需要设置请求首部信息
        xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
        xhr.send("username="+username);//把文本框中输入的用户名当做参数发送给服务器
    }
}
function ajaxFunction(){
   var xmlHttp;
   try{ // Firefox,Opera 8.0+,Safari
        xmlHttp=new XMLHttpRequest();
    }
    catch (e){
       try{// Internet Explorer
             xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
          }
        catch (e){
          try{
             xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
          }
          catch (e){}
          }
    }

    return xmlHttp;
 }

3.ValidateUsernameServlet

package app.servlet;

import java.io.IOException;

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

public class ValidateUsernameServlet extends HttpServlet {

    public void doGet(HttpServletRequest request,HttpServletResponse response)
            throws ServletException,IOException {
        response.setContentType("text/html;charset=utf-8");
        request.setCharacterEncoding("utf-8");
        String username = request.getParameter("username");
        //模拟数据库
        if(username==null||"".equals(username)){
            response.getWriter().write("用户名不能为空！");
        }else if("sa".equals(username)){
            response.getWriter().write("用户名已经存在");
        }else{
            response.getWriter().write("用户名可以使用");
        }
    }

    public void doPost(HttpServletRequest request,IOException {
        doGet(request,response);
    }

}

黑马day17 ajax&实现用户名自动刷新

猜你在找的Ajax相关文章