C#TCP读取所有数据-服务器端问题

我正在使用C#v4.0（.Net Framework v4）开发一个简单的TCP服务器应用程序：

我想完成这两个步骤：

客户端向服务器发送消息1（客户端可以是.net或java应用程序）
服务器将消息2作为对消息1的响应发送回客户端

我的服务器有问题，无法正确读取message1，除非我使用不合适的解决方案之一：

1）使用缓冲区只有1字节的MemoryStream（有效但缓慢）：

while (true)
{
    TcpClient tcpClient = tcpListener.AcceptTcpClient();
    NetworkStream networkStream = tcpClient.GetStream();
    MemoryStream memoryStream = new MemoryStream();
    int numberOfBytesRead = 0;
    byte[] buffer = new byte[1]; // works but slow in case of big messages
    do
    {
        numberOfBytesRead = networkStream.Read(buffer, 0, buffer.Length);   
        memoryStream.Write(buffer, 0, numberOfBytesRead);
    } while (networkStream.DataAvailable);
    if (memoryStream.Length > 0)
    {
        string message1 = new StreamReader(memoryStream).ReadToEnd();
        if (message1 == "message1")
        {
            using (StreamWriter streamWriter = new StreamWriter(networkStream))
            {
                string message2 = "message2";
                streamWriter.Write(message2);
                streamWriter.Flush();
            }
        }
    }
}

示例：如果message1.Length==12501并且我使用1024的缓冲区NetworkStream。Read（）循环只读取2048字节的message1，我认为NetworkStream。DataAvailable未返回正确的值！

2）使用线程。从NetworkStream读取到缓冲区后休眠（1000）（有效但缓慢）：

while (true)
{
    TcpClient tcpClient = tcpListener.AcceptTcpClient();
    NetworkStream networkStream = tcpClient.GetStream();
    MemoryStream memoryStream = new MemoryStream();
    int numberOfBytesRead = 0;
    byte[] buffer = new byte[8192]; 
    do
    {
        numberOfBytesRead = networkStream.Read(buffer, 0, buffer.Length);   
        memoryStream.Write(buffer, 0, numberOfBytesRead);
        Thread.Sleep(1000); // works but receiving gets slow
    } while (networkStream.DataAvailable);
    if (memoryStream.Length > 0)
    {
        string message1 = new StreamReader(memoryStream).ReadToEnd();
        if (message1 == "message1")
        {
            using (StreamWriter streamWriter = new StreamWriter(networkStream))
            {
                string message2 = "message2";
                streamWriter.Write(message2);
                streamWriter.Flush();
            }
        }
    }
}

3）使用StreamReader。ReadToEnd（）并在发送消息后关闭客户端的套接字1（有效，但服务器无法用消息2响应客户端）：

while (true)
{
    TcpClient tcpClient = tcpListener.AcceptTcpClient();
    NetworkStream networkStream = tcpClient.GetStream();
    StreamReader streamReader = new StreamReader(networkStream, true);
    string message1 = streamReader.ReadToEnd(); // blocks until client close its socket
    if (message1 == "message1")
    {
        using (StreamWriter streamWriter = new StreamWriter(networkStream))
        {
            string message2 = "message2";
            streamWriter.Write(message2); // if client close its sockets, the server cannot send this message
            streamWriter.Flush();
        }
    }
}

4）使用StreamReader循环。ReadLine（）并关闭客户端的套接字

while (true)
{
    TcpClient tcpClient = tcpListener.AcceptTcpClient();
    NetworkStream networkStream = tcpClient.GetStream();
    StreamReader streamReader = new StreamReader(networkStream);
    StringBuilder stringBuilder = new StringBuilder();
    while (!streamReader.EndOfStream)
    {
        stringBuilder.AppendLine(streamReader.ReadLine()); // blocks until client close its socket
    }
    string message1 = stringBuilder.ToString();
    if (message1 == "message1")
    {
        using (StreamWriter streamWriter = new StreamWriter(networkStream))
        {
            string message2 = "message2";
            streamWriter.Write(message2); // if client close its sockets, the server cannot send this message
            streamWriter.Flush();
        }
    }
}

5）为message1添加长度前缀（有效，但需要客户端向消息添加额外的字节，这对现有的java客户端不起作用）

while (true)
{
    TcpClient tcpClient = tcpListener.AcceptTcpClient();
    NetworkStream networkStream = tcpClient.GetStream();
    MemoryStream memoryStream = new MemoryStream();
    byte[] bufferMessageLength = new byte[4];   // sizeof(int)
    networkStream.Read(bufferMessageLength, 0, bufferMessageLength.Length);  
    int messageLength = BitConverter.ToInt32(bufferMessageLength, 4);
    byte[] bufferMessage = new byte[messageLength]; 
    networkStream.Read(bufferMessage, 0, bufferMessage.Length); 
    memoryStream.Write(buffer, 0, bufferMessage.Length);
    if (memoryStream.Length > 0)
    {
        string message1 = new StreamReader(memoryStream).ReadToEnd();
        if (message1 == "message1")
        {
            using (StreamWriter streamWriter = new StreamWriter(networkStream))
            {
                string message2 = "message2";
                streamWriter.Write(message2);
                streamWriter.Flush();
            }
        }
    }
}

关于这些问题，在不使用上述解决方案的情况下，从客户端读取所有数据的最佳方法是什么？

而不是使用networkStream.DataAvailable，在消息的开头附加数据大小。例如，您的消息长度为12501使用前4个字节作为消息长度。

首先定义从缓冲区读取数据的方法

public static void ReadStream(NetworkStream reader, byte[] data)
{
    var offset = 0;
    var remaining = data.Length;
    while (remaining > 0)
    {
        var read = reader.Read(data, offset, remaining);
        if (read <= 0)
            throw new EndOfStreamException
                (String.Format("End of stream reached with {0} bytes left to read", remaining));
        remaining -= read;
        offset += read;
    }
}

然后从流中读取数据。

var bytesRead = 0;
var offset = 0;
TcpClient tcpClient = tcpListener.AcceptTcpClient();
NetworkStream networkStream = tcpClient.GetStream();
var bufferMessageSize = new byte[4]; // int32
ReadStream(networkStream, bufferMessageSize);
var messageSize = BitConverter.ToInt32(bufferMessageSize, 4); // bytesToRead
var bufferMessage = new byte[messageSize];
ReadStream(networkStream, bufferMessage);

// Now Respond back Client here
// networkStream.Write();

如果通信是面向线路的，那么StreamReader.ReadLine()可能是合适的。

ReadLine（）；从当前流中读取一行字符，并返回数据作为字符串。

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