使用来自网络的编码 ISO-8859-1 解析 XML

Question

我需要从 Web 读取一个编码为 ISO-8859-1 的 XML 文件。用它创建一个 XmlDocument 后，我​​尝试将它的一些 InnerText 转换为 UTF。但这没有用。然后我尝试更改 HttpClient 上的编码。响应字符串的格式正确，但在创建 XmlDocument 时，应用程序崩溃并出现异常：HRESULT: 0xC00CE55F 或 XML 字符串上出现非预期字符。我该如何解决这个问题？

代码片段：

private static async Task<string> GetResultsAsync(string uri)
        {
            var client = new HttpClient();
            var response = await client.GetByteArrayAsync(uri);
            var responseString = Encoding.GetEncoding("iso-8859-1").GetString(response, 0, response.Length - 1);
            return responseString;
        }

public static async Task GetPodcasts(string url)
        {
            var progrmas = await GetGroupAsync("prog");
            HttpClient client = new HttpClient();

            //Task<string> pedido = client.GetStringAsync(url);
            //string res = await pedido; //Gets the string with the wrong chars, LoadXml doesn't fails

            res = await GetResultsAsync(url); //Gets the string properly formatted
            XmlDocument doc = new XmlDocument();

            doc.LoadXml(res);  //Crashes here
            XmlElement root = doc.DocumentElement;

            XmlNodeList nodes = root.SelectNodes("//item");

            //Title
            var node_titles = root.SelectNodes("//item/title");
            IEnumerable<string> query_titles = from nodess in node_titles select nodess.InnerText;
            List<string> list_titles = query_titles.ToList();
            //........

            for (int i = 0; i < list_titles.Count; i++)
            {
                PodcastItem podcast = new PodcastItem();
                string title = list_titles[i];


                //First attempt to convert a field from the XmlDocument, with the wrong chars. Only replaces the bad encoding with a '?':

                //Encoding iso = Encoding.GetEncoding("ISO-8859-1");
                //Encoding utf8 = Encoding.UTF8;
                //byte[] utfBytes = utf8.GetBytes(title);
                //byte[] isoBytes = Encoding.Convert(utf8, iso, utfBytes);
                //string msg = iso.GetString(isoBytes, 0, isoBytes.Length - 1);

                PodcastItem dataItem = new PodcastItem(title + pubdate, title, link, description, "", pubdate);
                progrmas.Items.Add(dataItem);
            }

        }

Answer 1

我不确定您为什么要尝试对自己进行编码，但它在您身上崩溃如此严重的原因可能是因为您忘记获取数组的最后一个字节。这段代码对我有用：

    static async Task<string> LoadDecoced()
    {
        var client = new HttpClient();
        var response = await client.GetByteArrayAsync("http://www.rtp.pt/play/podcast/469");
        var responseString = Encoding
           .GetEncoding("iso-8859-1")
           .GetString(response, 0, response.Length); // no -1 here, we want all bytes!
        return responseString;
    }

如果我让 HttpClient 弄清楚你的代码对我有用：

    static async Task<string> Load()
    {
        var hc = new HttpClient();
        string s = await hc.GetStringAsync("http://www.rtp.pt/play/podcast/469");
        return s;
    }

    static void Main(string[] args)
    {

        var xd = new XmlDocument();
        string res = Load().Result;
        xd.LoadXml(res);
        var node_titles = xd.DocumentElement.SelectNodes("//item/title");

        Console.WriteLine(node_titles.Count);
    }

如果您使用的是非移动设备/非 WinRT，XmlDocument.Load 接受流也是如此：

    static async Task<Stream> LoadStream()
    {
        var hc = new HttpClient();
        var stream = await hc.GetStreamAsync("http://www.rtp.pt/play/podcast/469");
        return stream;
    }

    static void Main(string[] args)
    {

        var xd2 = new XmlDocument();
        xd2.Load(LoadStream().Result);

        var node_titles2 = xd2.DocumentElement.SelectNodes("//item/title");

        Console.WriteLine(node_titles2.Count);
    }

这是我控制台中的结果：

你确定你没有在其他地方编码吗？

作为一般建议：框架类能够处理最常见的编码场景。尝试让它工作，而不必摆弄 Encoding 类。