AJAX调用REST API返回NULL

各位大侠，小弟最近遇到一个难题，请各位不吝帮忙，先谢过，问题如下：

我可以通过IE8浏览器调用以下API
# Request
GET https://www.
# Response
{
    "date": "1410431279",
    "ticker": {
        "buy": "33.15",
        "high": "34.15",
        "last": "33.15",
        "low": "32.05",
        "sell": "33.16",
        "vol": "10532696.39199642"
    }
}
这个API还有以下的说明：All requests go over https protocol, The field 'contentType' in request header should be: 'application/x-www-form-urlencoded'. The root url is: https://www.

然后我在JS中想通过AJAX调用，缺发现跳出的信息窗是"用户名：null"，源代码如下：
 <script src="Js/jquery-1.4.2.js" type="text/javascript"></script>
    <script type="text/javascript">
        $(function () {
            $("#btnSave").click(
               function () {
                $.ajax({
                    type: "get",
                    contentType: "application/x-www-form-urlencoded",
                    dataType: "json",
                    url: "https://www.,
                    success: function (data) {
                        alert("用户名：" + data);
                    },
                    error: function (error) {
                        alert("出错：" + error.responseText);
                    }
                });
            }
            );

        })
    </script>