WebClient client = new WebClient();
client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
client.Proxy= new WebProxy("http://proxyserver:80/", true);
Stream data = client.OpenRead("请求页面地址");
StreamReader reader = new StreamReader(data);
string s = reader.ReadToEnd();
Console.WriteLine(s);
data.Close();
reader.Close();