C＃在TCP客户端/服务器上发送图像

Question

  im trying to make a client and server that the server sends image to the client

到目前为止，仅可能发送一个图像，而其他的则不被神秘的错误所接受，我试图找出错误但没有运气...这是服务器代码：public void SendImage（Image img）{

        TcpClient tempClient = _Client;

        if (tempClient.Connected) //If the client is connected
        {
            NetworkStream stream = tempClient.GetStream();
            Bitmap bmp = new Bitmap(img);
            BinaryWriter bw = new BinaryWriter(stream);
            MemoryStream ms = new MemoryStream();
            bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
            byte[] buffer = ms.ToArray();
          byte[] lengthbts=  Get8LengthByte(buffer);
          stream.Write(lengthbts,0,8);
          stream.Write(buffer, 0, buffer.Length );
          stream.Flush();
        //   bw.Close();



        }

    }
    byte[] Get8LengthByte(byte[] bytes)
    {
        string length = bytes.Length.ToString();
        while (length.Length < 8)
        {
            length = "0" + length;
        }
        return Encoding.Default.GetBytes(length);
    }

这是客户代码

       NetworkStream stream = client.GetStream();
            //Bitmap bmp = new Bitmap(img);
            BinaryReader br = new BinaryReader(stream);
            byte[] datalen = new byte[8];
            br.Read(datalen, 0, 8);
            string lenStr = (Encoding.Default.GetString(datalen));
            int len = int.Parse(lenStr);//BitConverter.ToInt32(datalen, 0);//
            Console.WriteLine(len);
            byte[] buffer = new byte[len];
            br.Read(buffer, 0, buffer.Length);
              MemoryStream ms = new MemoryStream(buffer, 0, buffer.Length);
            ms.Position = 0;
            Image img = Image.FromStream(ms);
            Invoke(new MethodInvoker(delegate()
            {
                pictureBox1.Image = img;
            }
            ));

想法是先发送图片字节的长度作为8字节长度，例如，如果字节长度为10，则8字节长度为“ 00000010”，则接收到的第一个图像非常好且快速，但是第二个返回的错误可以使8字节长度为整数，使byte []收到的内容更像是“？/// ???” 诸如此类的事情，如果有人可以帮助我弄清楚，我将非常感激

Answer 1

很难说。 我可以建议的一件事是：如果长度值正确，并且文件大于4K，则应继续读取直到长度结束，例如：

int offset=0;
int bLeft=len;
byte[] buffer = new byte[len];
while (bLeft > 0)
{
    int ret = br.read(buffer, offset, bLeft);
    if (ret > 0)
    {
         bLeft-=ret;
         offset+=ret; 
    }
    else if (ret == 0) 
    {
        // the socket has been closed
    }
    else {
       // there is an error in the socket
    }
}

如果您的问题是发送文件的长度，那么我不会弄乱字符串和编码，只需发送4个字节并读取4个字节，就像这样

    byte[] bLength = new byte[4];
    int len = 123456;
    bLength[0] = (byte)((len & 0xff000000) >> 24);
    bLength[1] = (byte)((len & 0x00ff0000) >> 16);
    bLength[2] = (byte)((len & 0x0000ff00) >> 8);
    bLength[3] = (byte)(len & 0xff);
    // Send 4 bytes

    // Read only 4 bytes
    byte[] buff = new byte[4];
    br.read(buff, 0, 4);
    int length = (int)(buff[0] << 24) | (int)(buff[1] << 16) | (int)(buff[2] << 8) | buff[3];