标签：res request div 内容 length cep buffer man ons
你写的.NET（C#）下载程序是否会遇到过这样的问题？－－ContentLength=-1．
例如，有如下代码：
HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url); HttpWebResponse webResponse = null; webRequest.Timeout = 100000; webResponse = (HttpWebResponse)webRequest.GetResponse(); Stream resStream = webResponse.GetResponseStream(); StreamReader xtReader = new StreamReader(resStream); int DataSize = webResponse.ContentLength;//ContentLength 等于-1
会发现ContentLength=-1，这是为什么呢？！
用http分析工具会发现，原因原来是很简单的，这是因为某些网站服务器在发送响应内容时，会用gzip或 deflate等压缩算法压缩网页的内容，这样能使网页内容的数据包体积大大减小，从而加快了网络传输，这样客户端的浏览器显示网页也加快了。就是因为这 个gzip或 deflate功能，使得网页数据在进行http传输时不会在header里加上ContentLength属性，所以程序取回 来的ContentLength 的数值就默认为-1了（而 没有gzip或 deflate功能的网页肯定会ContentLength具体数值）
改进：
byte[] arraryByte = new byte[1024]; try { HttpWebRequest req = (HttpWebRequest)WebRequest.Create(filePath); req.Method = "Get"; ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Ssl3; ServicePointManager.ServerCertificateValidationCallback += (object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors) => true; using (HttpWebResponse wr = (HttpWebResponse)req.GetResponse()) { Stream stream = wr.GetResponseStream(); //读取到内存 MemoryStream stmMemory = new MemoryStream(); byte[] buffer1 = new byte[1024 * 100]; //每次从文件读取1024个字节。 int i; //将字节逐个放入到Byte 中 while ((i = stream.Read(buffer1, 0, buffer1.Length)) > 0) { stmMemory.Write(buffer1, 0, i); } arraryByte = stmMemory.ToArray(); stmMemory.Close(); stream.Close(); } }
标签：res request div 内容 length cep buffer man ons
原文地址：https://www.cnblogs.com/peterYong/p/9756477.html
