通过DataOutputStream.writeUTF（）发送信息时出现奇怪的字符

Question

I'm trying to send information json format through socket but when the server sends and arrive at the beginning they have a certain special characters.

like ♠ * {Trace: {listfile ....}}

Class Client

public static void Connect() throws UnknownHostException, IOException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException{
    String OUTPUT = getProperties();
    try{
    Tunnel = new Socket( HOSTNAME , PORT );
    InputStream = new DataInputStream(Tunnel.getInputStream());
    OutputStream = new DataOutputStream(Tunnel.getOutputStream());
    String OutSerial = "{ Trace: { "+OUTPUT+"}}";
    OutputStream.writeUTF(OutSerial);
    Tunnel.close();
    }catch(Exception e){}
}

Class Server

public static void Listening(String port) throws IOException, InterruptedException{
        BufferedReader Input;
        int PORT = Integer.parseInt(port);
        sc =new ServerSocket(PORT);
        so =new Socket();
        so = sc.accept();
        Debug.DebugM("It is connected a bot.");
        Input = new BufferedReader(new InputStreamReader(so.getInputStream()));
        Output = new DataOutputStream(so.getOutputStream());
        String INPUT = null;
        while((INPUT = Input.readLine()) != null){

            System.out.println(INPUT);

        }}

How to solve? Thanks

Answer 1

What's happening is that the writeUTF() method is prepending some bytes. Use readUTF() instead of readLine() like you're doing.

See DataInput for the byte structure of the UTF representation.

Like so:

Input = new DataInputStream(so.getInputStream());
String INPUT = Input.readUTF();
System.out.println(INPUT);

Answer 2

You shouldn't use writeUTF() for strings of arbitrary size. It's limited to a 16-bit length. And you can't use it at all unless the peer is going to use readUTF() to read it.

I would use BufferedWriter.write()/newLine() to write, and BufferedReader.readLine() to read.