C# 读取网页源代码

using System.Net;
using System.IO;

WebRequest

private string GetWebRequest(string url)
{
    Uri uri = new Uri(url);
    WebRequest myReq = WebRequest.Create(uri);
    WebResponse result = myReq.GetResponse();
    Stream receviceStream = result.GetResponseStream();
    StreamReader readerOfStream = new StreamReader(receviceStream, System.Text.Encoding.GetEncoding("utf-8"));
    string strHTML = readerOfStream.ReadToEnd();
    readerOfStream.Close();
    receviceStream.Close();
    result.Close();
    return strHTML;
}

HttpWebRequest 

private string GetHttpWebRequest(string url)
{
    Uri uri = new Uri(url);
    HttpWebRequest myReq = (HttpWebRequest)WebRequest.Create(uri);
    myReq.UserAgent = "User-Agent:Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705";
    myReq.Accept = "*/*";
    myReq.KeepAlive = true;
    myReq.Headers.Add("Accept-Language", "zh-cn,en-us;q=0.5");
    HttpWebResponse result = (HttpWebResponse)myReq.GetResponse();
    Stream receviceStream = result.GetResponseStream();
    StreamReader readerOfStream = new StreamReader(receviceStream, System.Text.Encoding.GetEncoding("utf-8"));
    string strHTML = readerOfStream.ReadToEnd();
    readerOfStream.Close();
    receviceStream.Close();
    result.Close();
    return strHTML;
}

WebClient

private string GetWebClient(string url)
{
    string strHTML = "";
    WebClient myWebClient = new WebClient();
    Stream myStream = myWebClient.OpenRead(url);
    StreamReader sr = new StreamReader(myStream, System.Text.Encoding.GetEncoding("utf-8"));
    strHTML = sr.ReadToEnd();
    myStream.Close();
    return strHTML;
}

还有一种使用WebBrower的方法，这里就不讨论了。

另外编码方式，比如“utf-8”要填写具体网页的编码方式。

可以用正则表达式将网页中的编码方式进行提取，再写入网页内容流时加个判断就好了。

可以看到HttpWebRequest 方式最复杂，但确提供了更多的选择性。

有的网站检测客户端的UserAgent！如163.com，你如果使用WebClient WebRequest方式获取时，将获取到的是错误提示页面内容。

而通过HttpWebRequest 就没问题。