Windows Phone get value from url with xml code

问题

I am trying to get live currency rate from this url: http://www.webservicex.net/CurrencyConvertor.asmx/ConversionRate?FromCurrency=GBP&ToCurrency=LTL

This is what I tried:

public void getRate(string howmuch, string from, string to)
    {
        int hmuch = int.Parse(howmuch);
        string url = "http://www.webservicex.net/CurrencyConvertor.asmx/ConversionRate?FromCurrency=GBP&ToCurrency=LTL";
        var xml = XDocument.Load(url);
        var result = xml.Descendants("double");
        btn.Content = result;
    }

I get an error from XDocument.Load that I need to pass URI from filesystem, not URL from web. I didn't found correct way on the web to do this in windows phone, only with full C#. How to properly get that value between double tags?

回答1:

You can try using WebClient to download XML content from internet :

WebClient wc = new WebClient();
wc.DownloadStringCompleted += DownloadCompleted;
wc.DownloadStringAsync(new Uri(" http://www.webservicex.net/CurrencyConvertor.asmx/ConversionRate?FromCurrency=GBP&ToCurrency=LTL"));

Then use XDocument.Parse() to load it to XDocument object :

private void DownloadCompleted(object sender, DownloadStringCompletedEventArgs e)
{
    if (e.Error == null)
    {
        XDocument xdoc = XDocument.Parse(e.Result);
        var result = xml.Root;
        btn.Content = result;
    }
}

Note that your XML has default namespace so it should be handled a bit differently (your current try won't work even if the XDocument was created successfully).

回答2:

Found a solution after ~4 hours:

This is how I call my function and convert result:

double rate = await getRate("GBP", "LTL");
string res = System.Convert.ToString(rate);
output.Text = res;

Note that method from which you call this function must be declared async as function itself, otherwise you can't use await operator.

Function:

public async Task<double> getRate(string from, string to)
        {
            string xml = string.Empty;
            Uri url = new Uri("http://www.webservicex.net/CurrencyConvertor.asmx/ConversionRate?FromCurrency="+from+"&ToCurrency="+to);
            HttpClient httpClient = new HttpClient();
            httpClient.DefaultRequestHeaders.TryAddWithoutValidation("Accept", "text/html,application/xhtml+xml,application/xml");
            var response = await httpClient.GetAsync(url);
            using (var responseStream = await response.Content.ReadAsStreamAsync())
            using (var streamReader = new StreamReader(responseStream))
            {
               xml = streamReader.ReadToEnd();
            }
            XDocument xDoc = XDocument.Parse(xml);
            XNamespace xmlns = "http://www.webserviceX.NET/";
            string value = (string)xDoc.Element(xmlns + "double");
            return System.Convert.ToDouble(value);
        }

Also don't forget to include needed headers:

using System.Net;
using System.Xml;
using System.Xml.Linq;
using System.Net.Http;
using System.Threading.Tasks;

来源：https://stackoverflow.com/questions/24971191/windows-phone-get-value-from-url-with-xml-code

标签

xml

windows-phone

rate