post请求 url后面加参数 接收不到的，必须 放到send（"use"=user）形式
还要加上
xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
servlet
1 package cn.itcast.controller; 2 3 import java.io.IOException; 4 import javax.servlet.ServletException; 5 import javax.servlet.annotation.WebServlet; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 @WebServlet("/servlet/ServletDemo2") 11 public class ServletDemo2 extends HttpServlet { 12 private static final long serialVersionUID = 1L; 13 14 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 15 } 16 17 public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 18 //System.out.println("ServletDemo2 doPost running"); 19 String username = request.getParameter("username"); 20 String password = request.getParameter("password"); 21 System.out.println(username+":"+password); 22 } 23 24 }
jsp
1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2 <html> 3 <head> 4 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5 <title>AJAX进行post方式的请求测试</title> 6 </head> 7 <body> 8 <input type="button" id="b1" name="b1" value="测试与服务器的通信"/> 9 <div id="d1"> 10 11 </div> 12 <script type="text/javascript"> 13 14 window.onload=function(){ 15 document.getElementById("b1").onclick = function(){ 16 //获取xmlhttpRequest对象 17 var xhr = createXmlHttpRequest(); 18 //注册状态变化的回调函数 19 xhr.onreadystatechange = function(){ 20 if (xhr.readyState == 4) { 21 if (xhr.status == 200 || xhr.status == 304) { 22 //什么都不做 23 } 24 } 25 } 26 //初始化xmlhttpRequest对象，即open 27 xhr.open("POST", "/ajaxday02/servlet/ServletDemo2?time=" + new Date().getTime()); 28 //设置请求消息头，告知服务器，发送的正文数据的类型。 29 xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 30 //发送数据 31 xhr.send("username=admin&password=123"); 32 } 33 } 34 function createXmlHttpRequest(){ 35 var xmlHttp; 36 try{ //Firefox, Opera 8.0+, Safari 37 xmlHttp=new XMLHttpRequest(); 38 }catch (e){ 39 try{ //Internet Explorer 40 xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); 41 }catch (e){ 42 try{ 43 xmlHttp=new ActiveXObject("Microsoft.XMLHTTP"); 44 }catch (e){} 45 } 46 } 47 return xmlHttp; 48 } 49 50 </script> 51 </body> 52 </html>