封装XMLHttpReuqest
//xmlHttp.js
var Request = new Object();
Request.reqList = [];
function createXMLRequest()
{
var xmlHttp=false;
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e){
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (E){
xmlHttp = false;
}
}
if (!xmlHttp && typeof XMLHttpRequest!='undefined')
{
xmlHttp = new XMLHttpRequest();
}
return xmlHttp;
}
Request.send = function(url, method, callback, data)
{
var xmlHttp=createXMLRequest();
xmlHttp.onreadystatechange = function()
{
if (xmlHttp.readyState == 4)
{
if (xmlHttp.status < 400)
{
callback(xmlHttp,data);
}
else
{
alert("当加载数据时发生错误 :\n" + xmlHttp.status+ "/" + xmlHttp.statusText);
}
//删除XMLHTTP，释放资源
try {
delete xmlHttp;
xmlHttp = null;
} catch (e) {}
}
}
//如果以POST方式回发服务器
if (method=="POST")
{
xmlHttp.open("POST", url, true);
xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlHttp.send(data);
Request.reqList.push(xmlHttp);
}
//以GET方式请求
else
{
xmlHttp.open("GET", url, true);
xmlHttp.send(null);
Request.reqList.push(xmlHttp);
}
return xmlHttp;
}
//全部清除XMLHTTP数组元素，释放资源
Request.clearReqList = function()
{
var ln = Request.reqList.length;
for(var i=0; i<ln; i++)
{
var xmlHttp = Request.reqList[i];
if(xmlHttp)
{
try{
delete xmlHttp;
} catch (e) {}
}
}
Request.reqList = [];
}
//进一步封装XMLHTTP以GET方式发送请求时的代码
Request.sendGET = function(url,callback)
{
Request.clearReqList();
return Request.send(url, "GET", callback, null);
}
//进一步封装XMLHTTP以POST方式发送请求时的代码
Request.sendPOST = function(url, callback,data)
{
Request.clearReqList();
Request.send(url, "POST", callback, data);
}
HelloWorld 示例:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>无标题页</title>
<script type="text/javascript" src="xmlHttp.js"></script>
<script type="text/javascript">
function callback(req,data)
{
document.getElementById("msg").innerHTML = req.responseText;
}
</script>
</head>
<body>
<input id="Button1" type="button" value="button" onclick="Request.sendGET('HelloWorld.txt', callback)" />
<div id="msg"></div>
</body>
</html>
HelloWorld.txt
就一行:HelloWorld
