Question

这是我的JS代码。这在IE中完美工作。如果我在浏览器中粘贴请求链接，那么我确实会得到JSON回复，但是当我运行此代码时。我没有收到任何雅虎或Google请求的回复。虽然在IE中工作得很好。

//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]); 
} 

这是越来越显示错误在Chrome调试器

的XMLHttpRequest不能加载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响应预检请求未通过访问控制检查：否“访问控制允许来源”标题存在于请求的资源。因此不允许原产地'null'访问。

Answer 1

我有使用WebClient替代的解决方案，调用此方法使用AJAX货币转换

 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"); 
      } 
     }