Onkyo eISCP

package com.example.onkyorc;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.os.StrictMode;
import android.view.View;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.EOFException;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void buttonClicked(View view) {
        MainActivity instance = new MainActivity();

        if (view.getId() == R.id.btnPWR) {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);

            //instance.queryCommand("PWRQSTN",true);
            instance.sendCommand("PWR01", true);
        }
    }

    private static final String DEFAULT_EISCP_IP = "192.168.1.33";
    private static final int DEFAULT_EISCP_PORT = 60128;
    private static Socket eiscpSocket_ = null;
    private static DataOutputStream out_ = null;
    private static DataInputStream in_ = null;
    private static boolean connected_ = false;

    public boolean connectSocket() {
        return connectSocket(DEFAULT_EISCP_IP, DEFAULT_EISCP_PORT);
    }

    public boolean connectSocket(String ip, int eiscpPort) {
        if (ip == null || ip.equals("")) ip = DEFAULT_EISCP_IP;
        if (eiscpPort == 0) eiscpPort = DEFAULT_EISCP_PORT;

        try {
            //1. creating a socket to connect to the server
            eiscpSocket_ = new Socket(ip, eiscpPort);
            System.out.println("Connected to " + ip + " on port " + eiscpPort);

            //2. get Input and Output streams
            out_ = new DataOutputStream(eiscpSocket_.getOutputStream());
            System.out.println("out_Init");
            out_.flush();

            System.out.println("inInit");
            connected_ = true;
        } catch (UnknownHostException unknownHost) {
            System.err.println("You are trying to connect to an unknown host!");
        } catch (IOException ioException) {
            ioException.printStackTrace();
        }

        return connected_;
    }

    public boolean closeSocket() {
        //4: Closing connection
        try {
            if (in_ != null) in_.close();
            if (out_ != null) out_.close();
            if (eiscpSocket_ != null) eiscpSocket_.close();

            System.out.println("closed connections");
            connected_ = false;
        } catch (IOException ioException) {
            ioException.printStackTrace();
        }

        return connected_;
    }

    public static String convertStringToHex(String str, boolean dumpOut) {
        char[] chars = str.toCharArray();
        String out_put = "";

        if (dumpOut) System.out.println("Ascii: " + str);
        if (dumpOut) System.out.print("Hex: ");

        StringBuffer hex = new StringBuffer();

        for (int i = 0; i < chars.length; i++) {
            out_put = Integer.toHexString((int) chars[i]);
            if (out_put.length() == 1) hex.append("0");
            hex.append(out_put);

            if (dumpOut)
                System.out.print("0x" + (out_put.length() == 1 ? "0" : "") + out_put + " ");
        }

        if (dumpOut) System.out.println("");

        return hex.toString();
    }

    public StringBuilder getEiscpMessage(String command) {
        StringBuilder sb = new StringBuilder();
        int eiscpDataSize = 2 + command.length() + 1; // this is the eISCP data size

        sb.append("ISCP");

        // the following are all in HEX representing one char
        // 4 char Big Endian Header
        sb.append((char) 0x00);
        sb.append((char) 0x00);
        sb.append((char) 0x00);
        sb.append((char) 0x10);

        // 4 char  Big Endian data size
        sb.append((char) ((eiscpDataSize >> 24) & 0xFF));
        sb.append((char) ((eiscpDataSize >> 16) & 0xFF));
        sb.append((char) ((eiscpDataSize >> 8) & 0xFF));
        sb.append((char) (eiscpDataSize & 0xFF));

        // eiscp_version = "01";
        sb.append((char) 0x01);

        // 3 chars reserved = "00"+"00"+"00";
        sb.append((char) 0x00);
        sb.append((char) 0x00);
        sb.append((char) 0x00);

        //  eISCP data
        // Start Character
        sb.append("!");

        // eISCP data - unittype char '1' is receiver
        sb.append("1");

        // eISCP data - 3 char command and param    ie PWR01
        sb.append(command);

        // msg end - EOF
        //sb.append((char) Integer.parseInt("0D", 16));
        sb.append((char) 0x0D);

        System.out.println("eISCP data size: " + eiscpDataSize + "(0x" + Integer.toHexString(eiscpDataSize) + ") chars");
        System.out.println("eISCP msg size: " + sb.length() + "(0x" + Integer.toHexString(sb.length()) + ") chars");

        return sb;
    }

    public void sendCommand(String command, boolean closeSocket) {
        StringBuilder sb = getEiscpMessage(command);

        if (connectSocket()) {
            try {
                System.out.println("sending " + sb.length() + " chars: ");
                convertStringToHex(sb.toString(), true);

                out_ = new DataOutputStream(new LoggingOutputStream(eiscpSocket_.getOutputStream()));
                out_.writeBytes(sb.toString());
                out_.flush();
                System.out.println("sent!");
            } catch (IOException ioException) {
                ioException.printStackTrace();
            }
        }

        if (closeSocket) closeSocket();
    }

    public class LoggingOutputStream extends FilterOutputStream {
        private long count;

        public LoggingOutputStream(OutputStream out) { super(out); }

        @Override
        public void write(int b) throws IOException {
            System.out.printf("writing byte %3d: %2h (%s)%n", count, b, (char) b);
            count++;
            super.write(b);
        }
    }

    public String queryCommand(String command, boolean closeSocket) {
        String retVal = "";

        sendCommand(command, false);

        // now listen for the response
        if (connected_) {
            try {
                in_ = new DataInputStream(eiscpSocket_.getInputStream());
                byte[] responseBytes = new byte[32];
                int numBytesReceived = 0;

                numBytesReceived = in_.read(responseBytes);
                retVal = new String(responseBytes);
                System.out.println("received " + numBytesReceived + " bytes: \"" + retVal + "\"");

            } catch (EOFException eofException) {
                System.out.println("received: \"" + retVal + "\"");
            } catch (IOException ioException) {
                ioException.printStackTrace();
            }
        } else
            System.out.println(" Not Connected to Receive ");

        if (closeSocket) closeSocket();

        return retVal;
    }

    public static void main(String[] args) { } // main

}