雅虎/谷歌财务 JSON 在 Chrome 中不起作用

Question

这是我的 JS 代码。这在 IE 中完美运行。如果我将请求链接粘贴到浏览器中，那么我确实会收到 JSON 回复，但是当我运行此代码时。我没有得到任何雅虎或谷歌请求的回复。不过在 IE 中效果很好。

//var url1 = "http://finance.google.com/finance/info?client=ig&q=AAPL";
var yah_url1 = 'http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20yahoo.finance.quotes%20where%20symbol%20in%20("';
var yah_url2 = '")%0A%09%09&format=json&diagnostics=true&env=http%3A%2F%2Fdatatables.org%2Falltables.env&callback=';

function btn_stocks_click()
{
    var div_table = document.getElementById("div_stock_table");
    var btn_stocks = document.getElementById("btn_stocks");
    div_table.style.display =  (div_table.style.display == 'none') ? 'block' : 'none'; 
    btn_stocks.value = (btn_stocks.value == "Show Stocks") ? "Hide Stocks" : "Show Stocks";
    getJSONReply("AAPL");
}

function getJSONReply() 
{
    var req = yah_url1.concat(arguments[0]);
    var url_req = req.concat(yah_url2);
    alert(url_req);
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function() 
    {
        if (xhr.readyState == 4 && xhr.status == 200) 
        {
            alert(xhr.responseText.length);
        }
    }
    xhr.open('GET', url_req, true);
    xhr.setRequestHeader('Access-Control-Allow-Headers', '*');
    xhr.setRequestHeader('Access-Control-Allow-Origin', '*');
    xhr.setRequestHeader('Access-Control-Allow-Methods', 'GET');
    xhr.addEventListener("load", reqListener);
    xhr.send();
}

function reqListener() // This was coded for Google Finance reply as it had other characters apart from reply.
{
    var sub1 = this.responseText.substring(5,this.responseText.length);
    var sub2 = sub1.substring(0, sub1.length - 2);
    parse_JSON(sub2);
}

function parse_JSON()
{
    var response = arguments[0];
    alert(arguments[0]);
}

这是 Chrome 调试器中显示的错误

XMLHttpRequest 无法加载 http://query.yahooapis.com/v1/public/yql?q=select%20%2a%20from%20yahoo.finance.quotes%20where%20symbol%20in%20%28%22AAPL%22%29%0A%09%09&env=http%3A%2F%2Fdatatables.org%2Falltables.env&format=json 对预检请求的响应未通过访问控制检查：请求的资源上不存在“Access-Control-Allow-Origin”标头。因此不允许访问 Origin 'null'。

Answer 1

我有使用WebClient的替代解决方案，使用ajax调用这个方法来转换货币

        public JsonResult convertCurrencyUsingGoogle(decimal amount, string from, string to)
        {
            try
            {
                WebClient WebClient = new WebClient();
                from = from.ToUpper();
                to = to.ToUpper();

                try
                {

                    var CurrencyQuery = new StringBuilder();
                    CurrencyQuery.Append("https://www.google.com/finance/converter");
                    CurrencyQuery.AppendFormat("?a={0}", amount);
                    CurrencyQuery.AppendFormat("&from={0}", from);
                    CurrencyQuery.AppendFormat("&to={0}", to);

                    string response = WebClient.DownloadString(CurrencyQuery.ToString()); //response returns as page
                    var responsestring = response.Split(new string[] { "class=bld>" }, StringSplitOptions.None); // get element which contains money 
                    var finalresponse = responsestring[1].Split(new string[] { to }, StringSplitOptions.None); // split curreny type 

                    return Json(String.Format("{0:G29}", Convert.ToDecimal(finalresponse[0].Trim()))); //return currency
                }
                catch (Exception e)
                {
                  return Json("error");
                }
            }
            catch (Exception e)
            {
                return Json("error");
            }
        }