c# - 无法下载 utf-8 网页内容

Question

我有简单的代码可以从越南网站获得响应:http://vnexpress.net ，但是有一个小问题。第一次，它下载正常，但之后，内容包含这样的未知符号:�\b\0\0\0\0\0\0�\a`I�%&/m....有什么问题？

    string address = "http://vnexpress.net";
    WebClient webClient = new WebClient();
    webClient.Headers.Add("user-agent", "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11 AlexaToolbar/alxg-3.1");
    webClient.Encoding = System.Text.Encoding.UTF8;
    return webClient.DownloadString(address);

Answer 1

您会发现响应是 GZip 压缩的。似乎没有办法使用 WebClient 下载它，除非您创建派生类并修改基础 HttpWebRequest 以允许自动解压缩。

这是你应该如何做到的:

    public class MyWebClient : WebClient
    {
        protected override WebRequest GetWebRequest(Uri address)
        {
            var req = base.GetWebRequest(address) as HttpWebRequest;
            req.AutomaticDecompression = DecompressionMethods.GZip;
            return req;
        }
    }

并使用它:

string address = "http://vnexpress.net";
MyWebClient webClient = new MyWebClient();
webClient.Headers.Add("user-agent", "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11 AlexaToolbar/alxg-3.1");
webClient.Encoding = System.Text.Encoding.UTF8;
return webClient.DownloadString(address);