套接字重置异常-Java

Question

I am trying to send a ByteBuffer array over a socket on the port 25565 on the address "localhost". But for some reason, Java is throwing a connection reset exception when doing input.read() . Could someone please tell me whats going on?

Sender:

private static Socket socket;

public static void main(String[] args) throws IOException {
    socket = new Socket("localhost", 25565);
    String Password = "1234";
    ByteBuffer Buffer = ByteBuffer.allocate(1 + Password.getBytes().length);
    Buffer.put((byte) 0x00);
    Buffer.putShort((short) Password.getBytes().length);
    Buffer.put(Password.getBytes());
    DataOutputStream output = new DataOutputStream(socket.getOutputStream());
    output.write(Buffer.array());
}

public static void sendBytes(byte[] myByteArray) throws IOException {
    DataOutputStream output = new DataOutputStream(socket.getOutputStream());
    output.write("LOL".getBytes());
    output.flush();
}

Receiver:

public static void main(String[] args) {
    try {
        ServerSocket ServerSocket = new ServerSocket(25565);
        System.out.println("Waiting for connection...");
        Socket socket = ServerSocket.accept();
        DataInputStream Input = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
        System.out.println(Input.read());
        ServerSocket.close();
        socket.close();
    } catch (Exception e) {
        if(e instanceof SocketTimeoutException) {
            System.out.println("THE SOCKET TIMED OUT!");
        }
        else {
            e.printStackTrace();
        }
    }
}

Stack trace:

java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:189)
at java.net.SocketInputStream.read(SocketInputStream.java:121)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
at java.io.BufferedInputStream.read(BufferedInputStream.java:265)
at java.io.FilterInputStream.read(FilterInputStream.java:83)
at net.networking.Receiver.main(Receiver.java:17)

NOTE: Yes, I do know that just using input.read() will not get the whole ByteBuffer array I'm trying to send. But right now I just want to read the first byte and print it out to the console.

Answer 1

1. You're not closing the connection in the sender, so it gets reset when the process exits.

    private static Socket socket; public static void main(String[] args) throws IOException { socket = new Socket("localhost", 25565); String Password = "1234"; sendBytes(Password.getBytes()); output.close(); } public static void sendBytes(byte[] myByteArray) throws IOException { ByteBuffer Buffer = ByteBuffer.allocate(3 + myByteArray.length); Buffer.put((byte) 0x00); Buffer.putShort((short) myByteArray.length); Buffer.put(myByteArray); DataOutputStream output = new DataOutputStream(socket.getOutputStream()); output.write(Buffer.array()); output.flush(); } 

2. You're only reading one byte and then closing the connection. You need to read the entire transmission. If you close a socket with unread data still pending, the connection is reset. Also, if you want to handle exceptions separately, catch them separately. Don't use instanceof .

    public static void main(String[] args) { try { ServerSocket ServerSocket = new ServerSocket(25565); System.out.println("Waiting for connection..."); Socket socket = ServerSocket.accept(); DataInputStream Input = new DataInputStream(new BufferedInputStream(socket.getInputStream())); byte b = Input.readByte(); short dataLen = Input.readShort(); byte[] data = new byte[dataLen]; Input.readFully(data); // use data as needed... System.out.println("Data received"); Input.close(); ServerSocket.close(); } catch (SocketTimeoutException e) { System.out.println("THE SOCKET TIMED OUT!"); } catch (Exception e) { e.printStackTrace(); } }