Question

这就是场景：我正在建立TCP连接（对自己）以字符串格式发送一些数据。我创建一个连接，我发送数据，我立即关闭连接（我不想同步等待数据）。在发送字符串之前，我将其长度（data.Length）附加到字符串的前面，因此我知道在接收字符串时要读取多少数据。我有StreamSocketListener监听来自TCP连接的传入数据，我为外界制作了一些＆＃34; helper＆＃34; -class来简化内容。该类被实例化一次，并调用方法Start以开始侦听连接。这就是场景。当我发送数据（对我自己，但这不重要）时，我在方法System.OutOfMemoryException中得到StreamReadLine。

对我而言，为什么会发生这种情况并不是很明显，所以这就是我在这里的原因。我希望有人之前已经解决了这个问题并且知道问题是什么。

public delegate void TCPRequestHandler(string data, string sender);
public class TCPSocketListener
{
    private int port;
    private StreamSocketListener listener;
    private bool mIsActive = false;
    private event TCPRequestHandler requestHandlerCallback;

    public bool isActive
    {
        get { return mIsActive; }
    }

    public TCPSocketListener(int port, TCPRequestHandler requestHandlerCallback)
    {
        this.port = port;
        this.requestHandlerCallback = requestHandlerCallback;
    }

    public async void Start()
    {
        if (!mIsActive)
        {
            mIsActive = true;
            listener = new StreamSocketListener();
            listener.Control.QualityOfService = SocketQualityOfService.Normal;
            listener.ConnectionReceived += Listener_ConnectionReceived;
            await listener.BindServiceNameAsync(port.ToString());
        }
    }

    public void Stop()
    {
        if (mIsActive)
        {
            listener.Dispose();
            mIsActive = false;
        }
    }

    async void Listener_ConnectionReceived(StreamSocketListener sender, StreamSocketListenerConnectionReceivedEventArgs args)
    {
        string data = await ExtractRequestData(args.Socket);
        await Task.Run(() => requestHandlerCallback(data, args.Socket.Information.RemoteHostName.CanonicalName));
    }

    private async Task<string> ExtractRequestData(StreamSocket socket)
    {
        //Initialize IO classes
        DataReader reader = new DataReader(socket.InputStream);
        //DataWriter writer = new DataWriter(socket.OutputStream);
        //writer.UnicodeEncoding = Windows.Storage.Streams.UnicodeEncoding.Utf8;

        // get the data on the stream
        string data = await StreamReadLine(reader);

        socket.Dispose();
        return data;
    }

    private static async Task<string> StreamReadLine(DataReader reader)
    {
        System.Diagnostics.Debug.WriteLine("reading data");
        var stringHeader = await reader.LoadAsync(4);

        if (stringHeader == 0)
        {
            System.Diagnostics.Debug.WriteLine("Header of the data was 0, for whatever reason");
            return "null";
        }
        int strLength = reader.ReadInt32();
        uint numStrBytes = await reader.LoadAsync((uint)strLength);
        string data = reader.ReadString(numStrBytes);
        System.Diagnostics.Debug.WriteLine("read " + data);
        return data;
    }
}

Answer 1

感谢Lasse和Stephen（对问题的评论），因为他们是对的。数据长度确实首先以数据为前缀，然后作为字节复制，而不是先将文本作为字节，然后将长度作为字节加前缀。

所以我所做的是创建一个总长度（有效载荷）的新字节数组，然后获取数据的字节，然后用数据长度填充前4个字节。像这样：

转让前：

// Add the length of the data at the start, so we know how much characters to read when receiving this
Int32 dataLength = data.Length;
// Add the data to be sent into the buffer
byte[] payload = new byte[sizeof(Int32) + (dataLength * sizeof(char))];
byte[] dataBytes = System.Text.Encoding.UTF8.GetBytes(data);
System.Buffer.BlockCopy(dataBytes, 0, payload, 4, dataBytes.Length);

payload[0] = (byte)(dataLength >> 24);
payload[1] = (byte)(dataLength >> 16);
payload[2] = (byte)(dataLength >> 8);
payload[3] = (byte)dataLength;

收到时：

var stringHeader = await reader.LoadAsync(4);
Int32 strLength = reader.ReadInt32();
uint numStrBytes = await reader.LoadAsync((uint)strLength);
string data = reader.ReadString(numStrBytes);

从DataReader读取数据时出现OutOfMemoryException

1 个答案: