Feat: FTP 서버 기본 구조 구현

- AndroidManifest.xml에 필요한 권한 추가 (INTERNET, STORAGE 등) - FTPResponse 클래스 생성: FTP 응답 코드 상수 정의 - FTPSession 클래스 생성: 개별 클라이언트 세션 처리 * 명령어 읽기/응답 보내기 기본 루프 * USER, PASS, QUIT, SYST, PWD, NOOP 명령어 처리 - FTPServer 클래스 생성: 메인 서버 로직 * ServerSocket으로 포트 2121에서 수신 대기 * ExecutorService로 다중 클라이언트 연결 관리 - FTPService 클래스 생성: 백그라운드 포그라운드 서비스 * 서버 시작/중지 Intent 처리 * 알림 채널 및 포그라운드 서비스 구현 - MainActivity UI 업데이트: 서버 제어 기능 * 시작/중지 버튼 추가 * 서버 상태 표시 * 런타임 권한 요청 처리 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
2026-01-01 02:46:18 +09:00
parent 509685936a
commit f08d8d66d8
50 changed files with 1459 additions and 0 deletions
--- a/app/.gitignore
+++ b/app/.gitignore
@@ -0,0 +1 @@
+/build
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -0,0 +1,38 @@
+plugins {
+    id 'com.android.application'
+}
+
+android {
+    compileSdk 36
+
+    defaultConfig {
+        applicationId "be.gyu.android.server.ftp"
+        minSdk 21
+        targetSdk 36
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+}
+
+dependencies {
+
+    implementation 'androidx.appcompat:appcompat:1.3.0'
+    implementation 'com.google.android.material:material:1.4.0'
+    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
+    testImplementation 'junit:junit:4.13.2'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
+}
--- a/app/proguard-rules.pro
+++ b/app/proguard-rules.pro
@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
--- a/app/src/androidTest/java/be/gyu/android/server/ftp/ExampleInstrumentedTest.java
+++ b/app/src/androidTest/java/be/gyu/android/server/ftp/ExampleInstrumentedTest.java
@@ -0,0 +1,26 @@
+package be.gyu.android.server.ftp;
+
+import android.content.Context;
+
+import androidx.test.platform.app.InstrumentationRegistry;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import static org.junit.Assert.*;
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+@RunWith(AndroidJUnit4.class)
+public class ExampleInstrumentedTest {
+    @Test
+    public void useAppContext() {
+        // Context of the app under test.
+        Context appContext = InstrumentationRegistry.getInstrumentation().getTargetContext();
+        assertEquals("be.gyu.android.server.ftp", appContext.getPackageName());
+    }
+}
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -0,0 +1,40 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="be.gyu.android.server.ftp">
+
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"
+        android:maxSdkVersion="32" />
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
+        android:maxSdkVersion="32" />
+    <uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
+    <uses-permission android:name="android.permission.READ_MEDIA_VIDEO" />
+    <uses-permission android:name="android.permission.READ_MEDIA_AUDIO" />
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.Gyub_sAndroidFTPServer">
+        <activity
+            android:name=".MainActivity"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+
+        <service
+            android:name=".FTPService"
+            android:enabled="true"
+            android:exported="false"
+            android:foregroundServiceType="dataSync" />
+    </application>
+
+</manifest>
--- a/app/src/main/java/be/gyu/android/server/ftp/FTPResponse.java
+++ b/app/src/main/java/be/gyu/android/server/ftp/FTPResponse.java
@@ -0,0 +1,68 @@
+package be.gyu.android.server.ftp;
+
+public class FTPResponse {
+    // 1xx - Positive Preliminary reply
+    public static final int RESTART_MARKER = 110;
+    public static final int SERVICE_READY_IN_N_MINUTES = 120;
+    public static final int DATA_CONNECTION_ALREADY_OPEN = 125;
+    public static final int FILE_STATUS_OK = 150;
+
+    // 2xx - Positive Completion reply
+    public static final int COMMAND_OK = 200;
+    public static final int COMMAND_NOT_IMPLEMENTED = 202;
+    public static final int SYSTEM_STATUS = 211;
+    public static final int DIRECTORY_STATUS = 212;
+    public static final int FILE_STATUS = 213;
+    public static final int HELP_MESSAGE = 214;
+    public static final int SYSTEM_TYPE = 215;
+    public static final int SERVICE_READY = 220;
+    public static final int SERVICE_CLOSING = 221;
+    public static final int DATA_CONNECTION_OPEN = 225;
+    public static final int CLOSING_DATA_CONNECTION = 226;
+    public static final int ENTERING_PASSIVE_MODE = 227;
+    public static final int USER_LOGGED_IN = 230;
+    public static final int REQUESTED_FILE_ACTION_OK = 250;
+    public static final int PATHNAME_CREATED = 257;
+
+    // 3xx - Positive Intermediate reply
+    public static final int USERNAME_OK_NEED_PASSWORD = 331;
+    public static final int NEED_ACCOUNT = 332;
+    public static final int FILE_ACTION_PENDING = 350;
+
+    // 4xx - Transient Negative Completion reply
+    public static final int SERVICE_NOT_AVAILABLE = 421;
+    public static final int CANNOT_OPEN_DATA_CONNECTION = 425;
+    public static final int CONNECTION_CLOSED = 426;
+    public static final int FILE_ACTION_NOT_TAKEN = 450;
+    public static final int ACTION_ABORTED = 451;
+    public static final int INSUFFICIENT_STORAGE = 452;
+
+    // 5xx - Permanent Negative Completion reply
+    public static final int SYNTAX_ERROR = 500;
+    public static final int SYNTAX_ERROR_PARAMETERS = 501;
+    public static final int COMMAND_NOT_IMPLEMENTED_502 = 502;
+    public static final int BAD_SEQUENCE = 503;
+    public static final int COMMAND_NOT_IMPLEMENTED_FOR_PARAMETER = 504;
+    public static final int NOT_LOGGED_IN = 530;
+    public static final int NEED_ACCOUNT_FOR_STORING = 532;
+    public static final int FILE_UNAVAILABLE = 550;
+    public static final int PAGE_TYPE_UNKNOWN = 551;
+    public static final int EXCEEDED_STORAGE = 552;
+    public static final int FILE_NAME_NOT_ALLOWED = 553;
+
+    public static String format(int code, String message) {
+        return code + " " + message + "\r\n";
+    }
+
+    public static String formatMultiline(int code, String[] messages) {
+        StringBuilder sb = new StringBuilder();
+        for (int i = 0; i < messages.length; i++) {
+            if (i < messages.length - 1) {
+                sb.append(code).append("-").append(messages[i]).append("\r\n");
+            } else {
+                sb.append(code).append(" ").append(messages[i]).append("\r\n");
+            }
+        }
+        return sb.toString();
+    }
+}
--- a/app/src/main/java/be/gyu/android/server/ftp/FTPServer.java
+++ b/app/src/main/java/be/gyu/android/server/ftp/FTPServer.java
@@ -0,0 +1,109 @@
+package be.gyu.android.server.ftp;
+
+import android.util.Log;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+public class FTPServer {
+    private static final String TAG = "FTPServer";
+    private static final int DEFAULT_PORT = 2121;
+    private static final int MAX_CONNECTIONS = 10;
+
+    private ServerSocket serverSocket;
+    private ExecutorService executorService;
+    private Thread acceptThread;
+    private boolean isRunning = false;
+    private int port;
+
+    public FTPServer() {
+        this(DEFAULT_PORT);
+    }
+
+    public FTPServer(int port) {
+        this.port = port;
+        this.executorService = Executors.newFixedThreadPool(MAX_CONNECTIONS);
+    }
+
+    public void start() {
+        if (isRunning) {
+            Log.w(TAG, "Server is already running");
+            return;
+        }
+
+        acceptThread = new Thread(() -> {
+            try {
+                serverSocket = new ServerSocket(port);
+                isRunning = true;
+                Log.i(TAG, "FTP Server started on port " + port);
+
+                while (isRunning && !Thread.currentThread().isInterrupted()) {
+                    try {
+                        Socket clientSocket = serverSocket.accept();
+                        Log.i(TAG, "New client connection from: " + clientSocket.getInetAddress());
+
+                        FTPSession session = new FTPSession(clientSocket);
+                        executorService.execute(session);
+
+                    } catch (IOException e) {
+                        if (isRunning) {
+                            Log.e(TAG, "Error accepting connection: " + e.getMessage());
+                        }
+                    }
+                }
+            } catch (IOException e) {
+                Log.e(TAG, "Server socket error: " + e.getMessage());
+            } finally {
+                Log.i(TAG, "Server accept thread stopped");
+            }
+        });
+
+        acceptThread.start();
+    }
+
+    public void stop() {
+        if (!isRunning) {
+            Log.w(TAG, "Server is not running");
+            return;
+        }
+
+        Log.i(TAG, "Stopping FTP Server...");
+        isRunning = false;
+
+        try {
+            if (serverSocket != null && !serverSocket.isClosed()) {
+                serverSocket.close();
+            }
+        } catch (IOException e) {
+            Log.e(TAG, "Error closing server socket: " + e.getMessage());
+        }
+
+        if (acceptThread != null) {
+            acceptThread.interrupt();
+        }
+
+        executorService.shutdown();
+        try {
+            if (!executorService.awaitTermination(5, TimeUnit.SECONDS)) {
+                executorService.shutdownNow();
+            }
+        } catch (InterruptedException e) {
+            executorService.shutdownNow();
+            Thread.currentThread().interrupt();
+        }
+
+        Log.i(TAG, "FTP Server stopped");
+    }
+
+    public boolean isRunning() {
+        return isRunning;
+    }
+
+    public int getPort() {
+        return port;
+    }
+}
--- a/app/src/main/java/be/gyu/android/server/ftp/FTPService.java
+++ b/app/src/main/java/be/gyu/android/server/ftp/FTPService.java
@@ -0,0 +1,120 @@
+package be.gyu.android.server.ftp;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.content.Intent;
+import android.os.Build;
+import android.os.IBinder;
+import android.util.Log;
+
+import androidx.core.app.NotificationCompat;
+
+public class FTPService extends Service {
+    private static final String TAG = "FTPService";
+    private static final String CHANNEL_ID = "FTPServerChannel";
+    private static final int NOTIFICATION_ID = 1;
+
+    public static final String ACTION_START = "be.gyu.android.server.ftp.ACTION_START";
+    public static final String ACTION_STOP = "be.gyu.android.server.ftp.ACTION_STOP";
+
+    private FTPServer ftpServer;
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        Log.d(TAG, "Service created");
+        createNotificationChannel();
+    }
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        if (intent != null) {
+            String action = intent.getAction();
+
+            if (ACTION_START.equals(action)) {
+                startFTPServer();
+            } else if (ACTION_STOP.equals(action)) {
+                stopFTPServer();
+            }
+        }
+
+        return START_STICKY;
+    }
+
+    private void startFTPServer() {
+        if (ftpServer != null && ftpServer.isRunning()) {
+            Log.w(TAG, "FTP Server is already running");
+            return;
+        }
+
+        ftpServer = new FTPServer();
+        ftpServer.start();
+
+        Notification notification = createNotification("FTP Server is running on port " + ftpServer.getPort());
+        startForeground(NOTIFICATION_ID, notification);
+
+        Log.i(TAG, "FTP Server started");
+    }
+
+    private void stopFTPServer() {
+        if (ftpServer != null) {
+            ftpServer.stop();
+            ftpServer = null;
+        }
+
+        stopForeground(true);
+        stopSelf();
+
+        Log.i(TAG, "FTP Server stopped");
+    }
+
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+        if (ftpServer != null) {
+            ftpServer.stop();
+        }
+        Log.d(TAG, "Service destroyed");
+    }
+
+    @Override
+    public IBinder onBind(Intent intent) {
+        return null;
+    }
+
+    private void createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            NotificationChannel channel = new NotificationChannel(
+                    CHANNEL_ID,
+                    "FTP Server Service",
+                    NotificationManager.IMPORTANCE_LOW
+            );
+            channel.setDescription("FTP Server running notification");
+
+            NotificationManager manager = getSystemService(NotificationManager.class);
+            if (manager != null) {
+                manager.createNotificationChannel(channel);
+            }
+        }
+    }
+
+    private Notification createNotification(String contentText) {
+        Intent notificationIntent = new Intent(this, MainActivity.class);
+        PendingIntent pendingIntent = PendingIntent.getActivity(
+                this,
+                0,
+                notificationIntent,
+                PendingIntent.FLAG_IMMUTABLE
+        );
+
+        return new NotificationCompat.Builder(this, CHANNEL_ID)
+                .setContentTitle("FTP Server")
+                .setContentText(contentText)
+                .setSmallIcon(android.R.drawable.stat_sys_upload)
+                .setContentIntent(pendingIntent)
+                .build();
+    }
+}
--- a/app/src/main/java/be/gyu/android/server/ftp/FTPSession.java
+++ b/app/src/main/java/be/gyu/android/server/ftp/FTPSession.java
@@ -0,0 +1,142 @@
+package be.gyu.android.server.ftp;
+
+import android.util.Log;
+
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.net.Socket;
+
+public class FTPSession implements Runnable {
+    private static final String TAG = "FTPSession";
+
+    private final Socket controlSocket;
+    private BufferedReader reader;
+    private BufferedWriter writer;
+
+    private String username;
+    private boolean isAuthenticated = false;
+    private String currentDirectory = "/";
+    private boolean isRunning = true;
+
+    public FTPSession(Socket socket) {
+        this.controlSocket = socket;
+    }
+
+    @Override
+    public void run() {
+        try {
+            reader = new BufferedReader(new InputStreamReader(controlSocket.getInputStream()));
+            writer = new BufferedWriter(new OutputStreamWriter(controlSocket.getOutputStream()));
+
+            Log.d(TAG, "Client connected: " + controlSocket.getInetAddress());
+            sendResponse(FTPResponse.SERVICE_READY, "FTP Server ready");
+
+            String line;
+            while (isRunning && (line = reader.readLine()) != null) {
+                line = line.trim();
+                Log.d(TAG, "Command received: " + line);
+
+                if (line.isEmpty()) {
+                    continue;
+                }
+
+                handleCommand(line);
+            }
+        } catch (IOException e) {
+            Log.e(TAG, "Session error: " + e.getMessage());
+        } finally {
+            closeSession();
+        }
+    }
+
+    private void handleCommand(String commandLine) throws IOException {
+        String[] parts = commandLine.split("\\s+", 2);
+        String command = parts[0].toUpperCase();
+        String argument = parts.length > 1 ? parts[1] : "";
+
+        switch (command) {
+            case "USER":
+                handleUser(argument);
+                break;
+            case "PASS":
+                handlePass(argument);
+                break;
+            case "QUIT":
+                handleQuit();
+                break;
+            case "SYST":
+                handleSyst();
+                break;
+            case "PWD":
+                handlePwd();
+                break;
+            case "NOOP":
+                handleNoop();
+                break;
+            default:
+                sendResponse(FTPResponse.COMMAND_NOT_IMPLEMENTED_502, "Command not implemented");
+                break;
+        }
+    }
+
+    private void handleUser(String username) throws IOException {
+        this.username = username;
+        sendResponse(FTPResponse.USERNAME_OK_NEED_PASSWORD, "Username OK, password required");
+    }
+
+    private void handlePass(String password) throws IOException {
+        if (username == null || username.isEmpty()) {
+            sendResponse(FTPResponse.BAD_SEQUENCE, "Login with USER first");
+            return;
+        }
+
+        // Simple authentication - accept any password for now
+        // In production, implement proper authentication
+        isAuthenticated = true;
+        sendResponse(FTPResponse.USER_LOGGED_IN, "User logged in");
+    }
+
+    private void handleQuit() throws IOException {
+        sendResponse(FTPResponse.SERVICE_CLOSING, "Goodbye");
+        isRunning = false;
+    }
+
+    private void handleSyst() throws IOException {
+        sendResponse(FTPResponse.SYSTEM_TYPE, "UNIX Type: L8");
+    }
+
+    private void handlePwd() throws IOException {
+        if (!isAuthenticated) {
+            sendResponse(FTPResponse.NOT_LOGGED_IN, "Please login first");
+            return;
+        }
+        sendResponse(FTPResponse.PATHNAME_CREATED, "\"" + currentDirectory + "\" is current directory");
+    }
+
+    private void handleNoop() throws IOException {
+        sendResponse(FTPResponse.COMMAND_OK, "OK");
+    }
+
+    private void sendResponse(int code, String message) throws IOException {
+        String response = FTPResponse.format(code, message);
+        writer.write(response);
+        writer.flush();
+        Log.d(TAG, "Response sent: " + response.trim());
+    }
+
+    private void closeSession() {
+        try {
+            if (reader != null) reader.close();
+            if (writer != null) writer.close();
+            if (controlSocket != null && !controlSocket.isClosed()) {
+                controlSocket.close();
+            }
+            Log.d(TAG, "Session closed");
+        } catch (IOException e) {
+            Log.e(TAG, "Error closing session: " + e.getMessage());
+        }
+    }
+}
--- a/app/src/main/java/be/gyu/android/server/ftp/MainActivity.java
+++ b/app/src/main/java/be/gyu/android/server/ftp/MainActivity.java
@@ -0,0 +1,122 @@
+package be.gyu.android.server.ftp;
+
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.app.ActivityCompat;
+import androidx.core.content.ContextCompat;
+
+import android.Manifest;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.os.Build;
+import android.os.Bundle;
+import android.widget.Button;
+import android.widget.TextView;
+import android.widget.Toast;
+
+public class MainActivity extends AppCompatActivity {
+
+    private static final int PERMISSION_REQUEST_CODE = 100;
+
+    private TextView statusTextView;
+    private Button startButton;
+    private Button stopButton;
+
+    private boolean isServerRunning = false;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+
+        initViews();
+        setupListeners();
+        requestPermissions();
+    }
+
+    private void initViews() {
+        statusTextView = findViewById(R.id.statusTextView);
+        startButton = findViewById(R.id.startButton);
+        stopButton = findViewById(R.id.stopButton);
+    }
+
+    private void setupListeners() {
+        startButton.setOnClickListener(v -> startFTPServer());
+        stopButton.setOnClickListener(v -> stopFTPServer());
+    }
+
+    private void requestPermissions() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
+            // Android 13+
+            if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_MEDIA_IMAGES)
+                    != PackageManager.PERMISSION_GRANTED) {
+                ActivityCompat.requestPermissions(this,
+                        new String[]{
+                                Manifest.permission.READ_MEDIA_IMAGES,
+                                Manifest.permission.READ_MEDIA_VIDEO,
+                                Manifest.permission.READ_MEDIA_AUDIO
+                        },
+                        PERMISSION_REQUEST_CODE);
+            }
+        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            // Android 6.0 - 12
+            if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
+                    != PackageManager.PERMISSION_GRANTED) {
+                ActivityCompat.requestPermissions(this,
+                        new String[]{
+                                Manifest.permission.READ_EXTERNAL_STORAGE,
+                                Manifest.permission.WRITE_EXTERNAL_STORAGE
+                        },
+                        PERMISSION_REQUEST_CODE);
+            }
+        }
+    }
+
+    private void startFTPServer() {
+        Intent serviceIntent = new Intent(this, FTPService.class);
+        serviceIntent.setAction(FTPService.ACTION_START);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            startForegroundService(serviceIntent);
+        } else {
+            startService(serviceIntent);
+        }
+
+        isServerRunning = true;
+        updateUI();
+        Toast.makeText(this, "FTP Server Started", Toast.LENGTH_SHORT).show();
+    }
+
+    private void stopFTPServer() {
+        Intent serviceIntent = new Intent(this, FTPService.class);
+        serviceIntent.setAction(FTPService.ACTION_STOP);
+        startService(serviceIntent);
+
+        isServerRunning = false;
+        updateUI();
+        Toast.makeText(this, "FTP Server Stopped", Toast.LENGTH_SHORT).show();
+    }
+
+    private void updateUI() {
+        if (isServerRunning) {
+            statusTextView.setText("Server Status: Running");
+            startButton.setEnabled(false);
+            stopButton.setEnabled(true);
+        } else {
+            statusTextView.setText("Server Status: Stopped");
+            startButton.setEnabled(true);
+            stopButton.setEnabled(false);
+        }
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        if (requestCode == PERMISSION_REQUEST_CODE) {
+            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                Toast.makeText(this, "Permissions granted", Toast.LENGTH_SHORT).show();
+            } else {
+                Toast.makeText(this, "Permissions denied. App may not work correctly.", Toast.LENGTH_LONG).show();
+            }
+        }
+    }
+}
--- a/app/src/main/res/drawable-v24/ic_launcher_foreground.xml
+++ b/app/src/main/res/drawable-v24/ic_launcher_foreground.xml
@@ -0,0 +1,30 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:aapt="http://schemas.android.com/aapt"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path android:pathData="M31,63.928c0,0 6.4,-11 12.1,-13.1c7.2,-2.6 26,-1.4 26,-1.4l38.1,38.1L107,108.928l-32,-1L31,63.928z">
+        <aapt:attr name="android:fillColor">
+            <gradient
+                android:endX="85.84757"
+                android:endY="92.4963"
+                android:startX="42.9492"
+                android:startY="49.59793"
+                android:type="linear">
+                <item
+                    android:color="#44000000"
+                    android:offset="0.0" />
+                <item
+                    android:color="#00000000"
+                    android:offset="1.0" />
+            </gradient>
+        </aapt:attr>
+    </path>
+    <path
+        android:fillColor="#FFFFFF"
+        android:fillType="nonZero"
+        android:pathData="M65.3,45.828l3.8,-6.6c0.2,-0.4 0.1,-0.9 -0.3,-1.1c-0.4,-0.2 -0.9,-0.1 -1.1,0.3l-3.9,6.7c-6.3,-2.8 -13.4,-2.8 -19.7,0l-3.9,-6.7c-0.2,-0.4 -0.7,-0.5 -1.1,-0.3C38.8,38.328 38.7,38.828 38.9,39.228l3.8,6.6C36.2,49.428 31.7,56.028 31,63.928h46C76.3,56.028 71.8,49.428 65.3,45.828zM43.4,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2c-0.3,-0.7 -0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C45.3,56.528 44.5,57.328 43.4,57.328L43.4,57.328zM64.6,57.328c-0.8,0 -1.5,-0.5 -1.8,-1.2s-0.1,-1.5 0.4,-2.1c0.5,-0.5 1.4,-0.7 2.1,-0.4c0.7,0.3 1.2,1 1.2,1.8C66.5,56.528 65.6,57.328 64.6,57.328L64.6,57.328z"
+        android:strokeWidth="1"
+        android:strokeColor="#00000000" />
+</vector>
--- a/app/src/main/res/drawable/ic_launcher_background.xml
+++ b/app/src/main/res/drawable/ic_launcher_background.xml
@@ -0,0 +1,170 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#3DDC84"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:padding="16dp"
+    tools:context=".MainActivity">
+
+    <TextView
+        android:id="@+id/titleTextView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Android FTP Server"
+        android:textSize="24sp"
+        android:textStyle="bold"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        android:layout_marginTop="32dp" />
+
+    <TextView
+        android:id="@+id/statusTextView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Server Status: Stopped"
+        android:textSize="16sp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/titleTextView"
+        android:layout_marginTop="24dp" />
+
+    <TextView
+        android:id="@+id/portTextView"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Port: 2121"
+        android:textSize="14sp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/statusTextView"
+        android:layout_marginTop="8dp" />
+
+    <Button
+        android:id="@+id/startButton"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Start Server"
+        android:minWidth="150dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/portTextView"
+        android:layout_marginTop="32dp" />
+
+    <Button
+        android:id="@+id/stopButton"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Stop Server"
+        android:minWidth="150dp"
+        android:enabled="false"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/startButton"
+        android:layout_marginTop="16dp" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>
--- a/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
+++ b/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
--- a/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml
+++ b/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>
--- a/app/src/main/res/mipmap-hdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-hdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-hdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-hdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-mdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-mdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-mdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-mdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xhdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xxhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xxhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xxhdpi/ic_launcher_round.webp
--- a/app/src/main/res/mipmap-xxxhdpi/ic_launcher.webp
+++ b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.webp
--- a/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.webp
+++ b/app/src/main/res/mipmap-xxxhdpi/ic_launcher_round.webp
--- a/app/src/main/res/values-night/themes.xml
+++ b/app/src/main/res/values-night/themes.xml
@@ -0,0 +1,16 @@
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <!-- Base application theme. -->
+    <style name="Theme.Gyub_sAndroidFTPServer" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_200</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/black</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_200</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <color name="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#FF000000</color>
+    <color name="white">#FFFFFFFF</color>
+</resources>
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Gyub_s Android FTP Server</string>
+</resources>
--- a/app/src/main/res/values/themes.xml
+++ b/app/src/main/res/values/themes.xml
@@ -0,0 +1,16 @@
+<resources xmlns:tools="http://schemas.android.com/tools">
+    <!-- Base application theme. -->
+    <style name="Theme.Gyub_sAndroidFTPServer" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_500</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_700</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>
--- a/app/src/test/java/be/gyu/android/server/ftp/ExampleUnitTest.java
+++ b/app/src/test/java/be/gyu/android/server/ftp/ExampleUnitTest.java
@@ -0,0 +1,17 @@
+package be.gyu.android.server.ftp;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
+ */
+public class ExampleUnitTest {
+    @Test
+    public void addition_isCorrect() {
+        assertEquals(4, 2 + 2);
+    }
+}