Java TCP Socket Byte Heap Memory Issue

问题:

I have a Java TCP Server Socket program that is expecting about 64 bytes of data from a piece of remote hardware. The Server code is:

public void run () throws Exception
{


    //Open a socket on localhost at port 11111

    ServerSocket welcomeSocket = new ServerSocket(11111);

    while(true) {

        //Open and Accept on Socket

        Socket connectionSocket = welcomeSocket.accept();
        DataInputStream dIn = new DataInputStream(connectionSocket.getInputStream());


        int msgLen = dIn.readInt();
        System.out.println("RX Reported Length: "+ msgLen);
        byte[] msg = new byte[msgLen];

        if(msgLen > 0 ) {
            dIn.readFully(msg);

            System.out.println("Message Length: "+ msg.length);
            System.out.println("Recv[HEX]: " + StringTools.toHexString(msg));
        }
    }
}

This works correctly as I am able to test locally with a simple ACK program:

public class ACK_TEST { 

    public static void main (String[] args)
    {

        System.out.println("Byte Sender Running");


        try
        {   
            ACK_TEST obj = new ACK_TEST ();
            obj.run();
        }
        catch (Exception e)
        {
            e.printStackTrace ();
        }


    }


    public void run () throws Exception
    {

        Socket clientSocket = new Socket("localhost", 11111); 
        DataOutputStream dOut = new DataOutputStream(clientSocket.getOutputStream());

        byte rtn[] = null;
        rtn = new byte[1];
        rtn[0] = 0x06; // ACK


        dOut.writeInt(rtn.length); // write length of the message
        dOut.write(rtn);           // write the message

        System.out.println("Byte Sent");
        clientSocket.close();
    }
}

And this correctly produces this output from the Server side:

However, when I deploy the same Server code on the Raspberry Pi and the hardware sends data to it, the data length is far greater and causes a heap memory issue (Even with the Heap pre-set at 512MB, which is definitely incorrect and unnecessary)

My presumption is I am reading the data wrong from the TCP socket as from the debug from the hardware, it's certainly not sending packets of this size.

Update: I have no access to the Client source code. I do however need to take the input TCP data stream, place it into a byte array, and then another function (Not shown) parses out some known HEX codes. That function expects a byte array input.

Update: I reviewed the packet documentation. It is a 10 byte header. The first Byte is a protocol identifier. The next 2 bytes is the Packet Length (Total number of bytes in the packet, including all the header bytes and checksum) and the last 7 are a Unique ID. Therefore, I need to read those 2 bytes and create a byte array that size.

回答1:

Apparently the length from the header is about 1GB. Looks like the problem on the other end. Don't you mix low/big endian encoding?