XMLHttpRequest和ActiveXObject学习

//var xmlHttpReq = new ActiveXObject("MSXML2.XMLHTTP.3.0");

//定义变量，存储对象  
var xmlHttp;
// 创建XMLHttpRequest对象
if (window.ActiveXObject) {
    xmlHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
} else if (window.XMLHttpRequest) {
    xmlHttpReq = new XMLHttpRequest();
}

xmlHttpReq.open("GET", "http://localhost:9090/html5/test", false);
xmlHttpReq.onreadystatechange = handleStateChange;
xmlHttpReq.send();

// xmlHttpReq.responseText
// xmlHttpReq.responseXML

var htmlObj = "";
htmlObj += "=============状态码=================
";
htmlObj += "status=" + xmlHttpReq.status + "
";
htmlObj += "statusText=" + xmlHttpReq.statusText + "
";
htmlObj += "=============头信息=================
";
htmlObj += "heads=" + xmlHttpReq.getAllResponseHeaders() + "
";
htmlObj += "Content-Length=" + xmlHttpReq.getResponseHeader("Content-Length") + "
";
htmlObj += "=============返回信息=================
";
htmlObj += "responseStream=" + xmlHttpReq.responseStream + "
";

var obj = document.getElementById("showDiv");
obj.innerHTML = htmlObj;

function handleStateChange() {
    // 请求的状态有5个值：0=未初始化；1=正在加载；2=已经加载；3=交互中；4=完成；
    if (xmlHttpReq.readyState == 4) {
        // 200对应OK，如404=未找到网页
        if (xmlHttpReq.status == 200) {
            // alert(xmlHttpReq.responseText);
        }
    }
}