c# - 如何以二进制帧格式发送数据(TCP)

Question

我需要将数据流式传输到 TCP 服务器并且之前没有做过。数据应为二进制帧格式。我用谷歌搜索并找到了这个教程，我认为它描述了我需要做的事情:

http://msdn.microsoft.com/en-us/library/system.net.sockets.tcpclient(v=vs.71).aspx

但我不知道如何以所需的格式创建数据，以便以正确的方式发送它。它应该是这种格式:

Field|Offset|    Type  | size(octets)
id   |  0   |unsign int|      1
name |  1   |Byte Array|      40
grade|  41  |sign float|      8 

例子:

Field| Data | InBytes  |
id   |  133 | 133      |
name |  247 | 247 0    |
grade|  0   | 0        |

我应该将 int、字节数组、 float 存储在什么数据类型中，我应该在哪里指定偏移量和大小，最后应该如何将它发送到服务器(在示例中，它们只发送一个字节数组)。

一个 C# 示例如何使用上面提供的链接中的代码发送这样的数据将不胜感激。

Answer 1

要表示要序列化(和反序列化)的数据，您可以使用结构并设置适当的元数据，让 CLR 为您完成剩下的工作。就像其他人在这里所说的那样，您需要处理端点上的数据包接收。此外，您还必须考虑接收方期望的字符集，因为您的数据中有一个字符串字段。以下代码是一个示例，说明如何实现该结构以将托管数据转换为二进制格式，并带有注释。

// setting the layout to sequential will prevent the compiler/JIT
// to reorder the struct fields
// NOTE: Observe here that the Charset used is Ansi. You may need to
// change this depending on the format expected by the receiver.
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
struct DataPacket
{

    [MarshalAs(UnmanagedType.U4)]
    public uint Id;

    // As I understood from your question, the Name field
    // has a prefixed size of 40 bytes. Attention here:
    // the SizeConst actually means '40 characters', not bytes
    // If you choose to use the Unicode charset, set SizeConst = 20
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 40)]
    public String Name;

    // This will be serialized in little endian format
    // in your question this field is 8 bytes long, which 
    // in c# corresponds to the double type. If you really mean
    // the float type (4 bytes), change here.
    public double Grade;

    // Calling this method will return a byte array with the contents
    // of the struct ready to be sent via the tcp socket.
    public byte[] Serialize()
    {
        // allocate a byte array for the struct data
        var buffer = new byte[Marshal.SizeOf(typeof(DataPacket))];

        // Allocate a GCHandle and get the array pointer
        var gch = GCHandle.Alloc(buffer, GCHandleType.Pinned);
        var pBuffer = gch.AddrOfPinnedObject();

        // copy data from struct to array and unpin the gc pointer
        Marshal.StructureToPtr(this, pBuffer, false);
        gch.Free();

        return buffer;
    }

    // this method will deserialize a byte array into the struct.
    public void Deserialize(ref byte[] data)
    {
        var gch = GCHandle.Alloc(data, GCHandleType.Pinned);
        this = (DataPacket)Marshal.PtrToStructure(gch.AddrOfPinnedObject(), typeof(DataPacket));
        gch.Free();
    }
}

用法:

DataPacket packet;
packet.Id = 1234;
packet.Name = "Marvin the paranoid robot";
packet.Grade = 9.2;

// serialize
var bytes = packet.Serialize();

// send via tcp
var tcp = new TcpClient(...); 
tcp.GetStream().Write(bytes, 0, bytes.Length);


// deserializing;
DataPacket receivedPacket;
receivedPacket.Deserialize(bytes);

您已经有了数据包，现在您需要处理接收器上的数据包接收。这部分你不需要全部手工完成，你可以使用一些工具，就像@jgauffin 说的。