向指定url发送请求与获取响应

            string url = @"https://www.baidu.com";

            //向指定服务器发起请求
            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
            //request.Proxy = null;
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            //获取响应内容长度
            long contentLength = response.ContentLength;
            //获取响应内容格式
            string contentType = response.ContentType;
            //获取服务器返回的响应流
            Stream receiveStream = response.GetResponseStream();
            //使用指定的编码创建文本读取流
            StreamReader readStream = new StreamReader(receiveStream, Encoding.UTF8);
            //读取响应内容
            string contentText = readStream.ReadToEnd();
            //关闭流
            response.Close();
            readStream.Close();