function xhr() {
    var xhr;
    try {
        if (window.ActiveXObject) {
            for ( var i = 8; i; i--) {
                try {
                    if (i == 2) {
                        xhr = new ActiveXObject("Microsoft.XMLHTTP");
                    } else {
                        xhr = new ActiveXObject("Msxml2.XMLHTTP." + i + ".0");
                        // xhr.setRequestHeader("Content-Type","text/xml");
                        xhr.setRequestHeader("charset", "UTF-8");
                    }
                    break;
                } catch (e) {
                    xhr = false;
                }
            }
        } else if (window.XMLHttpRequest) {
            xhr = new XMLHttpRequest();
            if (xhr.overrideMimeType) {
                xhr.overrideMimeType('text/xml');
            }
        }
    } catch (e) {
        xhr = false;
        alert("您的浏览器不支持ajax");
    }
    return xhr;
}
function Ajax(callBackFunc, method, url, async, data, eFunc) {
    var req = xhr();
    if (req) {
        req.onreadystatechange = function() {
            if (req.readyState == 4 && req.status == 200) {
                if (callBackFunc) {
                    callBackFunc(req);
                }
            } else {
                if (req.readyState == 4 && req.readyState > 200) {
                    if (eFunc) {
                        eFunc(req);
                    }
                }
            }
            if (req.readyState == 4) {
                req.onreadystatechange = {};
            }
        };
        method = method.toUpperCase();
        req.open(method, url, async);
        if (method == "POST") {
            req.setRequestHeader("Content-type",
                    "application/x-www-form-urlencoded");
        }
        if (data) {
            req.send(data);
        } else {
            req.send(null);
        }
    }
}