1、get
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> <script type="text/javascript"> function checkusername() { // 1.获取ajax引擎 var xhr = getXHR(); // 2.调用open方法准备发送 var url = 'checkUsername_ajax?username='+document.getElementById('username').value; console.log(url); xhr.open('get',url,true); // 3.发送请求 xhr.send(); // 4.指定回调函数 xhr.onreadystatechange = function () { // readystate是4并且status是200 if(xhr.readyState == 4 && xhr.status == 200){ document.getElementById("msg").innerHTML = xhr.responseText; } }; } function getXHR() { if(window.XMLHttpRequest) { return new window.XMLHttpRequest(); } else { return new window.ActiveXObject("Microsoft.XMLHTTP"); } } </script> </head> <body> <form action="" method="get"> <input type="text" name="username" id="username" onblur="checkusername()"/><br/><div id="msg"></div> <input type="text" name="address"/><br/> <input type="submit" value="login"/><br/> </form> </body> </html>
2、post
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</title> <script type="text/javascript"> function checkusername() { // 1.获取ajax引擎 var xhr = getXHR(); // 2.调用open方法准备发送 xhr.open('post','checkUsername_ajax',true); // 3.发送请求 (多个参数使用&符号连接) // xhr.send('username='+document.getElementById('username').value+'&address=nj'); xhr.send('username='+document.getElementById('username').value); // 4.指定回调函数 xhr.onreadystatechange = function () { // readystate是4并且status是200 if(xhr.readyState == 4 && xhr.status == 200){ document.getElementById("msg").innerHTML = xhr.responseText; } }; } function getXHR() { if(window.XMLHttpRequest) { return new window.XMLHttpRequest(); } else { return new window.ActiveXObject("Microsoft.XMLHTTP"); } } </script> </head> <body> <form action="" method="get"> <input type="text" name="username" id="username" onblur="checkusername()"/><br/><div id="msg"></div> <input type="text" name="address"/><br/> <input type="submit" value="login"/><br/> </form> </body> </html>
文中checkUsername_ajax是url地址