为什么我的客户套接字没有收到我的服务器套接字发送的内容

使用阻塞，stream.NET套接字我连接到服务器。 每当我读取less量的数据，一切顺利，数据被接收到我的缓冲区中：

using (var socket = new Socket(SocketType.Stream, ProtocolType.IP)) { socket.Connect(IPAddress.Parse("127.0.0.1"), 5000); byte[] buffer = new byte[BufferSize]; socket.Receive(buffer); // Here buffer doesn't always contain all data the server sent me? Console.WriteLine(Encoding.Default.GetString(buffer)); } 

但在某些情况下，我并没有收到服务器发给我的所有信息。 数据似乎被砍掉了。 这可能是什么原因？

Answer 1

这在Receive()方法中有logging ，重点是mine：

Receive方法将数据读入缓冲区参数并返回成功读取的字节数 。 您可以从面向连接和无连接的套接字调用接收。

当忽略返回值时，你将不知道你的缓冲区的哪一部分实际上包含了相关的数据。 根据使用的协议，您可能会提前或不知道内容的长度。 一些协议提供这个长度，其他协议完成时closures连接，另一个协议可以使用消息边界。

您必须将接收到的数据保存在另一个缓冲区中，并在没有更多数据可用或预期时返回或输出整个消息缓冲区。 这可以这样做：

 int BufferSize = 1024; using (var socket = new Socket(SocketType.Stream, ProtocolType.IP)) { socket.Connect(IPAddress.Parse("127.0.0.1"), 5000); byte[] buffer = new byte[BufferSize]; string message = ""; int bytesReceived; do { bytesReceived = socket.Receive(buffer); message += Encoding.ASCII.GetString(buffer, 0, bytesReceived); } while (bytesReceived > 0); Console.WriteLine(message); } 

接收到的字节是ASCII字符（按照制定的协议定义），所以每个接收到的字节表示一个字符（不能转换部分接收的多字节Unicode字符）。 字节被转换为一个string并附加到messagevariables。 代码循环直到服务器closures连接。

当事先知道消息大小时，根据使用的协议，您可以创build一个消息缓冲区，并在每个Receive()上复制数据：

 // Received using another Receive() call int messageSize = 1234; int totalBytesReceived = 0; byte[] messageBuffer = new byte[messageSize]; byte[] buffer = new byte[BufferSize]; int bytesReceived; do { bytesReceived = socket.Receive(buffer); // Copy the receive buffer into the message buffer, appending after // previously received data (totalBytesReceived). Buffer.BlockCopy(buffer, 0, messageBuffer, totalBytesReceived, bytesReceived); totalBytesReceived += bytesReceived; } while (bytesReceived > 0); // This assumes the connection wasn't closed prematurely. Console.WriteLine(Encoding.ASCII.GetString(messageBuffer)); 

这可以反过来被放在一个可重复的方法：

 public byte[] ReceiveMessage(Socket socket, int messageSize) { byte[] messageBuffer = new byte[messageSize]; int bytesReceived = 0; int totalBytesReceived = 0; do { byte[] buffer = new byte[BufferSize]; // Receive at most the requested number of bytes, or the amount the // buffer can hold, whichever is smaller. int toReceive = Math.Min(messageSize - totalBytesReceived, BufferSize); bytesReceived = socket.Receive(buffer, toReceive, SocketFlags.None); // Copy the receive buffer into the message buffer, appending after // previously received data (totalBytesReceived). Buffer.BlockCopy(buffer, 0, messageBuffer, totalBytesReceived, bytesReceived); totalBytesReceived += bytesReceived; } while (bytesReceived > 0); if (totalBytesReceived < messageSize) { throw new Exception("Server closed connection prematurely"); } return messageBuffer; } 

NetworkStream封装了一个套接字，但它与套接字本身具有相同的读取问题 。 您将不得不监视返回值，并保持调用Read()直到您收到所有字节。 具有GetStream()方法的TcpClient也一样 ，在你读完所有数据之前，你还必须继续读取其返回值。