(Ajax) Ajax的运行轨迹
一段Ajax的代码function checkUser(){ // Create xmlhttp objectvar xmlhttp;try{xmlhttp=new XMLHttpRequest();}catch(e){xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");} xmlhttp.onreadystatechange=function(){if(4==xmlhttp.readyState){alert('----');if(200==xmlhttp.status){// Get "data" which send back from Server..var message= xmlhttp.responseText;alert(message);if(message=="unique"){alert("Username is available!");}else{alert("Username is inavailable!");}}else{alert(" Oops...Inner occur");} }} xmlhttp.open("post", "LoginServlet", true);//Send Ajax Request to servletxmlhttp.setRequestHeader('Content-type','application/x-www-form-urlencoded');var paras = "usermane="+document.getElementById("ID").value;alert(paras);//Send Ajax with paras to Serverxmlhttp.send(paras);}
第一部分：从页面获取数据直接传到servlet
xmlhttp.open("post", "LoginServlet", true);//Send Ajax Request to servletxmlhttp.setRequestHeader('Content-type','application/x-www-form-urlencoded');var paras = "usermane="+document.getElementById("ID").value;alert(paras);//Send Ajax with paras to Serverxmlhttp.send(paras);
第二部分：从servlet中获取数据传到页面上
xmlhttp.onreadystatechange=function(){if(4==xmlhttp.readyState){alert('----');if(200==xmlhttp.status){// Get "data" which send back from Server..var message= xmlhttp.responseText;alert(message);if(message=="unique"){alert("Username is available!");}else{alert("Username is inavailable!");}}else{alert(" Oops...Inner occur");} }}第三部分：servlet的代码：
import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {PrintWriter out = response.getWriter();String usermane=request.getParameter("usermane");System.out.println(usermane);String res="";if(usermane.equals("justin")){res="occupied";}else{res="unique";}out.print(res);}} 运行的轨迹如下：
http://dl.iteye.com/upload/attachment/493475/df5e737f-6fd5-3e72-9ff4-98a625b3ca80.jpg
http://dl.iteye.com/upload/attachment/493477/087f47d1-2140-30da-87a7-848fcfc54e10.jpg
http://dl.iteye.com/upload/attachment/493479/d11836d4-7510-37d1-a43a-e4be7aeeaba6.jpg
http://dl.iteye.com/upload/attachment/493481/d6ad047d-dfa0-3608-b07a-86b3e1432322.jpg
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