ajax 基本用法

来源：互联网发布：ant编译java项目编辑：程序博客网时间：2024/06/05 02:28

index.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"%><html> <head> <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <SCRIPT type="text/javascript"> var req; window.onload=function(){ } function validate() { var zhi=document.getElementById('uname').value; var url="validate.jsp?uname="+escape(zhi); if(window.XMLHttpRequest){req = new XMLHttpRequest();} else if (window.ActiveXObject) {req = new ActiveXObject("Microsoft.XMLHTTP");}req.open("GET", url, true);req.onreadystatechange = callback;req.send(null); } function callback() { if(req.readyState == 4) { if(req.status == 200)////////////////////////////////////////////////////////////////////////////////////8+* { alert("req.status"+req.status); alert("req.readyState"+req.readyState); alert("req.responseText"+req.responseText); //alert("req.responseXML"+req.responseXML); var msg = req.responseXML.getElementsByTagName("msg")[0];setMsg(msg.childNodes[0].nodeValue); }else{ alert("Not able to retrieve description"+req.statusText); } } } function setMsg(msg) { alert(msg);mdiv = document.getElementById("usermsg");if(msg == "invalid") {mdiv.innerHTML = "<font color='red'>username exists</font>";} else {mdiv.innerHTML = "<font color='green'>congratulations! you can user this user</font>";}} </SCRIPT> </head> <body> <div align="center"> name:<input type="text" name = "uname" id="uname" onblur="validate()"><span id="usermsg"></span> pwd:<input type="password" name = "uid" > </div> </body></html>

validate.jsp

<%response.setContentType("text/xml");response.setHeader("Cache-Control", "no-store");response.setHeader("Pragma", "no-cache");response.setDateHeader("Expires", 0);response.getWriter().write("<msg>valid</msg>");%>

流行的ajax框架 DOJO，DWR， BUFFLO， JSON