weiweichen1985

//创建一个XMLHttpRequest对象
var xmlhttp;

//检测浏览器初始化XMLHttpRequest对象
function createXMLHttpRequest() {
if (window.ActiveXObject) {
var XmlHttpVersions = new Array("MSXML2.XMLHTTP.6.0", "MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0", "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP", "Microsoft.XMLHTTP");
for (var i = 0; i < XmlHttpVersions.length && !xmlhttp; i++) {
try {
// try to create XMLHttpRequest object
xmlhttp = new ActiveXObject(XmlHttpVersions[i]);
xmlhttp.validateOnParse = false;
}
catch (e) {
}
}
} else {
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
xmlhttp.validateOnParse = false;
if (xmlhttp.overrideMimeType) {
xmlhttp.overrideMimeType("text/xml");
}
}
}
// return the created object or display an error message
if (!xmlhttp) {
alert("Error creating the XMLHttpRequest object.");
} else {
return xmlhttp;
}
}
/**
发送AJAX请求的函数
webpage:一个WEB资源，可以是jsp页面,xml文档，servlet，action
key:传递的参数的名称[对于多个参数,可以写成"p1=aa&p2" ]
value:传递p2的值
callback:回调函数
*/
function sendAjaxRequest(webpage, key, value, callback) {
xmlhttp = createXMLHttpRequest();
if (xmlhttp) {
if (key != "" && value != "") {
if (webpage.indexOf("?") >= 0) {
xmlhttp.open("post", webpage + "&" + key + "=" + value + "&now=" + new Date().getTime(), true);
} else {
xmlhttp.open("post", webpage + "?" + key + "=" + value + "&now=" + new Date().getTime(), true);
}
} else {
xmlhttp.open("post", webpage, true);
}
//xmlhttp.setrequestheader("cache-control","no-cache");
xmlhttp.setRequestHeader("If-Modified-Since", "0");
xmlhttp.onreadystatechange = callback;
xmlhttp.send(null);
} else {
alert("XMLHttpRequest对象创建失败!!!");
}
}