feat: 원격 FTP 서버 탐색 기능 기본 구현

app/.gitignore

@@ -0,0 +1 @@
+/build

app/build.gradle.kts

@@ -0,0 +1,43 @@
+plugins {
+    alias(libs.plugins.android.application)
+}
+
+android {
+    namespace = "be.gyu.android.file.explorer"
+    compileSdk {
+        version = release(36)
+    }
+
+    defaultConfig {
+        applicationId = "be.gyu.android.file.explorer"
+        minSdk = 24
+        targetSdk = 36
+        versionCode = 1
+        versionName = "1.0"
+
+        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            isMinifyEnabled = false
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+}
+
+dependencies {
+    implementation(libs.appcompat)
+    implementation(libs.material)
+    implementation("commons-net:commons-net:3.10.0")
+    testImplementation(libs.junit)
+    androidTestImplementation(libs.ext.junit)
+    androidTestImplementation(libs.espresso.core)
+}

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

app/src/androidTest/java/be/gyu/android/file/explorer/ExampleInstrumentedTest.java

@@ -0,0 +1,26 @@
+package be.gyu.android.file.explorer;
+
+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.file.explorer", appContext.getPackageName());
+    }
+}

app/src/main/AndroidManifest.xml

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
+        tools:ignore="ScopedStorage" />
+    <uses-permission android:name="android.permission.INTERNET" />
+
+    <application
+        android:allowBackup="true"
+        android:dataExtractionRules="@xml/data_extraction_rules"
+        android:fullBackupContent="@xml/backup_rules"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.Gyub_sFileExplorer">
+        <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>
+
+        <activity
+            android:name=".RemoteStorageActivity"
+            android:exported="false" />
+
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="${applicationId}.provider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/provider_paths" />
+        </provider>
+    </application>
+
+</manifest>

app/src/main/java/be/gyu/android/file/explorer/DbHelper.java

@@ -0,0 +1,81 @@
+package be.gyu.android.file.explorer;
+
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class DbHelper extends SQLiteOpenHelper {
+
+    private static final String DATABASE_NAME = "remote_servers.db";
+    private static final int DATABASE_VERSION = 1;
+
+    public static final String TABLE_SERVERS = "servers";
+    public static final String COLUMN_ID = "_id";
+    public static final String COLUMN_HOST = "host";
+    public static final String COLUMN_PORT = "port";
+    public static final String COLUMN_USERNAME = "username";
+    public static final String COLUMN_PASSWORD = "password";
+
+    private static final String TABLE_CREATE =
+            "CREATE TABLE " + TABLE_SERVERS + " (" +
+                    COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
+                    COLUMN_HOST + " TEXT, " +
+                    COLUMN_PORT + " INTEGER, " +
+                    COLUMN_USERNAME + " TEXT, " +
+                    COLUMN_PASSWORD + " TEXT" +
+                    ");";
+
+    public DbHelper(Context context) {
+        super(context, DATABASE_NAME, null, DATABASE_VERSION);
+    }
+
+    @Override
+    public void onCreate(SQLiteDatabase db) {
+        db.execSQL(TABLE_CREATE);
+    }
+
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+        db.execSQL("DROP TABLE IF EXISTS " + TABLE_SERVERS);
+        onCreate(db);
+    }
+
+    public void addServer(RemoteServer server) {
+        SQLiteDatabase db = this.getWritableDatabase();
+        ContentValues values = new ContentValues();
+        values.put(COLUMN_HOST, server.getHost());
+        values.put(COLUMN_PORT, server.getPort());
+        values.put(COLUMN_USERNAME, server.getUsername());
+        values.put(COLUMN_PASSWORD, server.getPassword());
+        db.insert(TABLE_SERVERS, null, values);
+        db.close();
+    }
+
+    public List<RemoteServer> getAllServers() {
+        List<RemoteServer> serverList = new ArrayList<>();
+        String selectQuery = "SELECT  * FROM " + TABLE_SERVERS;
+        SQLiteDatabase db = this.getWritableDatabase();
+        Cursor cursor = db.rawQuery(selectQuery, null);
+
+        if (cursor.moveToFirst()) {
+            do {
+                RemoteServer server = new RemoteServer(
+                        cursor.getLong(cursor.getColumnIndexOrThrow(COLUMN_ID)),
+                        cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_HOST)),
+                        cursor.getInt(cursor.getColumnIndexOrThrow(COLUMN_PORT)),
+                        cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_USERNAME)),
+                        cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_PASSWORD))
+                );
+                serverList.add(server);
+            } while (cursor.moveToNext());
+        }
+        cursor.close();
+        db.close();
+        return serverList;
+    }
+}

app/src/main/java/be/gyu/android/file/explorer/FTPClientHelper.java

@@ -0,0 +1,60 @@
+package be.gyu.android.file.explorer;
+
+import org.apache.commons.net.ftp.FTPClient;
+import org.apache.commons.net.ftp.FTPFile;
+import org.apache.commons.net.ftp.FTPReply;
+
+import java.io.IOException;
+
+public class FTPClientHelper {
+
+    private FTPClient ftpClient;
+
+    public boolean connect(String host, int port, String username, String password) {
+        ftpClient = new FTPClient();
+        try {
+            ftpClient.connect(host, port);
+            int reply = ftpClient.getReplyCode();
+            if (!FTPReply.isPositiveCompletion(reply)) {
+                ftpClient.disconnect();
+                return false;
+            }
+            if (!ftpClient.login(username, password)) {
+                return false;
+            }
+            ftpClient.enterLocalPassiveMode();
+            return true;
+        } catch (IOException e) {
+            e.printStackTrace();
+            return false;
+        }
+    }
+
+    public void disconnect() {
+        if (ftpClient != null && ftpClient.isConnected()) {
+            try {
+                ftpClient.logout();
+                ftpClient.disconnect();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+
+    public FTPFile[] listFiles(String path) {
+        try {
+            // First, try to change the working directory.
+            if (ftpClient.changeWorkingDirectory(path)) {
+                // If successful, list files in the new directory.
+                return ftpClient.listFiles();
+            } else {
+                // If changing directory fails, it might be a file path, not a directory.
+                // Or the path is invalid. For now, we return null for simplicity.
+                return null;
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+            return null;
+        }
+    }
+}

app/src/main/java/be/gyu/android/file/explorer/FileAdapter.java

@@ -12,6 +12,15 @@ import java.util.List;
 public class FileAdapter extends RecyclerView.Adapter<FileAdapter.FileViewHolder> {
 
     private final List<FileItem> fileList;
+    private OnItemClickListener listener;
+
+    public interface OnItemClickListener {
+        void onItemClick(FileItem item);
+    }
+
+    public void setOnItemClickListener(OnItemClickListener listener) {
+        this.listener = listener;
+    }
 
     public FileAdapter(List<FileItem> fileList) {
         this.fileList = fileList;
@@ -33,6 +42,12 @@ public class FileAdapter extends RecyclerView.Adapter<FileAdapter.FileViewHolder
         } else {
             holder.icon.setImageResource(R.drawable.ic_file);
         }
+
+        holder.itemView.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onItemClick(fileItem);
+            }
+        });
     }
 
     @Override

app/src/main/java/be/gyu/android/file/explorer/MainActivity.java

@@ -25,18 +25,29 @@ import androidx.core.content.FileProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
+import org.apache.commons.net.ftp.FTPFile;
+
 import java.io.File;
 import java.util.ArrayList;
 import java.util.List;
 
 public class MainActivity extends AppCompatActivity implements FileAdapter.OnItemClickListener {
 
+    // Common
     private static final int REQUEST_CODE_MANAGE_EXTERNAL_STORAGE = 1;
     private RecyclerView recyclerView;
     private FileAdapter fileAdapter;
     private List<FileItem> fileList;
+
+    // Local Mode
     private File currentDirectory;
 
+    // Remote (FTP) Mode
+    private boolean isRemoteMode = false;
+    private RemoteServer remoteServer;
+    private FTPClientHelper ftpHelper;
+    private String currentRemotePath;
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -53,13 +64,141 @@ public class MainActivity extends AppCompatActivity implements FileAdapter.OnIte
         fileAdapter.setOnItemClickListener(this);
         recyclerView.setAdapter(fileAdapter);
 
-        if (checkStoragePermission()) {
-            loadFiles(Environment.getExternalStorageDirectory());
+        Intent intent = getIntent();
+        if (intent != null && intent.hasExtra("remote_server")) {
+            isRemoteMode = true;
+            remoteServer = (RemoteServer) intent.getSerializableExtra("remote_server");
+            ftpHelper = new FTPClientHelper();
+            connectAndLoadFtpFiles();
         } else {
-            requestStoragePermission();
+            isRemoteMode = false;
+            if (checkStoragePermission()) {
+                loadFiles(Environment.getExternalStorageDirectory());
+            } else {
+                requestStoragePermission();
+            }
         }
     }
 
+    // --- FTP Methods ---
+    private void connectAndLoadFtpFiles() {
+        setTitle("Connecting to " + remoteServer.getHost());
+        new Thread(() -> {
+            boolean success = ftpHelper.connect(remoteServer.getHost(), remoteServer.getPort(), remoteServer.getUsername(), remoteServer.getPassword());
+            runOnUiThread(() -> {
+                if (success) {
+                    Toast.makeText(MainActivity.this, "Connected", Toast.LENGTH_SHORT).show();
+                    loadFtpFiles("/");
+                } else {
+                    Toast.makeText(MainActivity.this, "Connection Failed", Toast.LENGTH_LONG).show();
+                    finish(); // Close activity if connection fails
+                }
+            });
+        }).start();
+    }
+
+    private void loadFtpFiles(String path) {
+        this.currentRemotePath = path;
+        setTitle(path);
+        new Thread(() -> {
+            FTPFile[] files = ftpHelper.listFiles(path);
+            runOnUiThread(() -> {
+                fileList.clear();
+                if (files != null) {
+                    for (FTPFile file : files) {
+                        if (file == null || file.getName() == null || file.getName().equals(".") || file.getName().equals("..")) continue;
+                        String fullPath = path.equals("/") ? "/" + file.getName() : path + "/" + file.getName();
+                        fileList.add(new FileItem(file.getName(), fullPath, file.isDirectory()));
+                    }
+                } else {
+                     Toast.makeText(this, "Cannot read this directory!", Toast.LENGTH_SHORT).show();
+                }
+                fileAdapter.notifyDataSetChanged();
+            });
+        }).start();
+    }
+
+    // --- Local Storage Methods ---
+    private void loadFiles(File directory) {
+        this.currentDirectory = directory;
+        if (directory != null) {
+            setTitle(directory.getName());
+            fileList.clear();
+            File[] files = directory.listFiles();
+            if (files != null) {
+                for (File file : files) {
+                    fileList.add(new FileItem(file.getName(), file.getAbsolutePath(), file.isDirectory()));
+                }
+            } else {
+                Toast.makeText(this, "Cannot read this directory!", Toast.LENGTH_SHORT).show();
+            }
+        }
+        fileAdapter.notifyDataSetChanged();
+    }
+
+    // --- Common Overridden Methods ---
+    @Override
+    public void onItemClick(FileItem item) {
+        if (isRemoteMode) {
+            if (item.isDirectory()) {
+                loadFtpFiles(item.getPath());
+            } else {
+                // TODO: Implement file download/open for FTP
+                Toast.makeText(this, "Opening remote files is not implemented yet.", Toast.LENGTH_SHORT).show();
+            }
+        } else {
+            File file = new File(item.getPath());
+            if (file.isDirectory()) {
+                if (file.canRead()) {
+                    loadFiles(file);
+                } else {
+                    Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show();
+                }
+            } else {
+                openFile(file);
+            }
+        }
+    }
+
+    @Override
+    public void onBackPressed() {
+        if (isRemoteMode) {
+            if (currentRemotePath != null && !currentRemotePath.equals("/")) {
+                int lastSlash = currentRemotePath.lastIndexOf('/');
+                String parentPath = (lastSlash > 0) ? currentRemotePath.substring(0, lastSlash) : "/";
+                loadFtpFiles(parentPath);
+            } else {
+                super.onBackPressed();
+            }
+        } else {
+            // Logic for local storage back press
+            StorageManager storageManager = (StorageManager) getSystemService(STORAGE_SERVICE);
+            List<StorageVolume> storageVolumes = storageManager.getStorageVolumes();
+            boolean isAtRootOfAVolume = false;
+            for (StorageVolume volume : storageVolumes) {
+                File volumePath = volume.getDirectory();
+                if (volumePath != null && currentDirectory.equals(volumePath)) {
+                    isAtRootOfAVolume = true;
+                    break;
+                }
+            }
+            if (currentDirectory != null && !isAtRootOfAVolume) {
+                loadFiles(currentDirectory.getParentFile());
+            } else {
+                super.onBackPressed();
+            }
+        }
+    }
+
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        if (isRemoteMode && ftpHelper != null) {
+            new Thread(() -> ftpHelper.disconnect()).start();
+        }
+    }
+
+    // --- Menu Methods ---
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         getMenuInflater().inflate(R.menu.main_menu, menu);
@@ -68,13 +207,20 @@ public class MainActivity extends AppCompatActivity implements FileAdapter.OnIte
 
     @Override
     public boolean onOptionsItemSelected(@NonNull MenuItem item) {
-        if (item.getItemId() == R.id.select_storage) {
+        int itemId = item.getItemId();
+        if (itemId == R.id.select_storage) {
             showStorageSelectionDialog();
             return true;
+        } else if (itemId == R.id.remote_storage) {
+            Intent intent = new Intent(this, RemoteStorageActivity.class);
+            startActivity(intent);
+            return true;
         }
         return super.onOptionsItemSelected(item);
     }
 
+    // --- Boilerplate Permission/File Handling ---
+
     private void showStorageSelectionDialog() {
         StorageManager storageManager = (StorageManager) getSystemService(STORAGE_SERVICE);
         List<StorageVolume> storageVolumes = storageManager.getStorageVolumes();
@@ -99,7 +245,19 @@ public class MainActivity extends AppCompatActivity implements FileAdapter.OnIte
         builder.show();
     }
 
-
+    private void openFile(File file) {
+        Uri uri = FileProvider.getUriForFile(this, getApplicationContext().getPackageName() + ".provider", file);
+        Intent intent = new Intent(Intent.ACTION_VIEW);
+        String mime = MimeTypeMap.getSingleton().getMimeTypeFromExtension(MimeTypeMap.getFileExtensionFromUrl(uri.toString()));
+        intent.setDataAndType(uri, mime);
+        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
+        try {
+            startActivity(intent);
+        } catch (Exception e) {
+            Toast.makeText(this, "Cannot open file", Toast.LENGTH_SHORT).show();
+        }
+    }
+    
     private boolean checkStoragePermission() {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
             return Environment.isExternalStorageManager();
@@ -125,75 +283,10 @@ public class MainActivity extends AppCompatActivity implements FileAdapter.OnIte
         }
     }
 
-    private void loadFiles(File directory) {
-        this.currentDirectory = directory;
-        if (directory != null) {
-            setTitle(directory.getName());
-            fileList.clear();
-            File[] files = directory.listFiles();
-            if (files != null) {
-                for (File file : files) {
-                    fileList.add(new FileItem(file.getName(), file.getAbsolutePath(), file.isDirectory()));
-                }
-            } else {
-                Toast.makeText(this, "Cannot read this directory!", Toast.LENGTH_SHORT).show();
-            }
-        }
-        fileAdapter.notifyDataSetChanged();
-    }
-
-    @Override
-    public void onItemClick(FileItem item) {
-        File file = new File(item.getPath());
-        if (file.isDirectory()) {
-            if (file.canRead()) {
-                loadFiles(file);
-            } else {
-                Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show();
-            }
-        } else {
-            openFile(file);
-        }
-    }
-
-    private void openFile(File file) {
-        Uri uri = FileProvider.getUriForFile(this, getApplicationContext().getPackageName() + ".provider", file);
-        Intent intent = new Intent(Intent.ACTION_VIEW);
-        String mime = MimeTypeMap.getSingleton().getMimeTypeFromExtension(MimeTypeMap.getFileExtensionFromUrl(uri.toString()));
-        intent.setDataAndType(uri, mime);
-        intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
-        try {
-            startActivity(intent);
-        } catch (Exception e) {
-            Toast.makeText(this, "Cannot open file", Toast.LENGTH_SHORT).show();
-        }
-    }
-
-    @Override
-    public void onBackPressed() {
-        // Check against all storage volume roots
-        StorageManager storageManager = (StorageManager) getSystemService(STORAGE_SERVICE);
-        List<StorageVolume> storageVolumes = storageManager.getStorageVolumes();
-        boolean isAtRootOfAVolume = false;
-        for (StorageVolume volume : storageVolumes) {
-            File volumePath = volume.getDirectory();
-            if (volumePath != null && currentDirectory.equals(volumePath)) {
-                isAtRootOfAVolume = true;
-                break;
-            }
-        }
-
-        if (currentDirectory != null && !isAtRootOfAVolume) {
-            loadFiles(currentDirectory.getParentFile());
-        } else {
-            super.onBackPressed();
-        }
-    }
-
     @Override
     public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
         super.onRequestPermissionsResult(requestCode, permissions, grantResults);
-        if (requestCode == REQUEST_CODE_MANAGE_EXTERNAL_STORAGE) {
+        if (requestCode == REQUEST_CODE_MANAGE_EXTERNAL_STORAGE && !isRemoteMode) {
             if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                 loadFiles(Environment.getExternalStorageDirectory());
             } else {
@@ -205,7 +298,7 @@ public class MainActivity extends AppCompatActivity implements FileAdapter.OnIte
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         super.onActivityResult(requestCode, resultCode, data);
-        if (requestCode == REQUEST_CODE_MANAGE_EXTERNAL_STORAGE) {
+        if (requestCode == REQUEST_CODE_MANAGE_EXTERNAL_STORAGE && !isRemoteMode) {
             if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
                 if (Environment.isExternalStorageManager()) {
                     loadFiles(Environment.getExternalStorageDirectory());

app/src/main/java/be/gyu/android/file/explorer/RemoteServer.java

@@ -0,0 +1,60 @@
+package be.gyu.android.file.explorer;
+
+import java.io.Serializable;
+
+public class RemoteServer implements Serializable {
+    private long id;
+    private String host;
+    private int port;
+    private String username;
+    private String password;
+
+    public RemoteServer(long id, String host, int port, String username, String password) {
+        this.id = id;
+        this.host = host;
+        this.port = port;
+        this.username = username;
+        this.password = password;
+    }
+
+    // Getters and Setters
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public String getHost() {
+        return host;
+    }
+
+    public void setHost(String host) {
+        this.host = host;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public void setPort(int port) {
+        this.port = port;
+    }
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+}

app/src/main/java/be/gyu/android/file/explorer/RemoteServerAdapter.java

@@ -0,0 +1,63 @@
+package be.gyu.android.file.explorer;
+
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+import java.util.List;
+
+public class RemoteServerAdapter extends RecyclerView.Adapter<RemoteServerAdapter.ServerViewHolder> {
+
+    private final List<RemoteServer> serverList;
+    private OnItemClickListener listener;
+
+    public interface OnItemClickListener {
+        void onItemClick(RemoteServer server);
+    }
+
+    public void setOnItemClickListener(OnItemClickListener listener) {
+        this.listener = listener;
+    }
+
+    public RemoteServerAdapter(List<RemoteServer> serverList) {
+        this.serverList = serverList;
+    }
+
+    @NonNull
+    @Override
+    public ServerViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_remote_server, parent, false);
+        return new ServerViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull ServerViewHolder holder, int position) {
+        RemoteServer server = serverList.get(position);
+        holder.host.setText(server.getHost());
+        holder.username.setText(server.getUsername());
+
+        holder.itemView.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onItemClick(server);
+            }
+        });
+    }
+
+    @Override
+    public int getItemCount() {
+        return serverList.size();
+    }
+
+    static class ServerViewHolder extends RecyclerView.ViewHolder {
+        TextView host;
+        TextView username;
+
+        public ServerViewHolder(@NonNull View itemView) {
+            super(itemView);
+            host = itemView.findViewById(R.id.server_host);
+            username = itemView.findViewById(R.id.server_username);
+        }
+    }
+}

app/src/main/java/be/gyu/android/file/explorer/RemoteStorageActivity.java

@@ -0,0 +1,92 @@
+package be.gyu.android.file.explorer;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.text.InputType;
+import android.widget.EditText;
+import android.widget.LinearLayout;
+import androidx.appcompat.app.AlertDialog;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import com.google.android.material.floatingactionbutton.FloatingActionButton;
+import java.util.List;
+
+public class RemoteStorageActivity extends AppCompatActivity implements RemoteServerAdapter.OnItemClickListener {
+
+    private DbHelper dbHelper;
+    private RemoteServerAdapter adapter;
+    private List<RemoteServer> serverList;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_remote_storage);
+
+        dbHelper = new DbHelper(this);
+        serverList = dbHelper.getAllServers();
+
+        RecyclerView recyclerView = findViewById(R.id.remote_storage_recycler_view);
+        recyclerView.setLayoutManager(new LinearLayoutManager(this));
+        adapter = new RemoteServerAdapter(serverList);
+        adapter.setOnItemClickListener(this);
+        recyclerView.setAdapter(adapter);
+
+        FloatingActionButton fab = findViewById(R.id.fab_add_remote_storage);
+        fab.setOnClickListener(view -> showAddServerDialog());
+    }
+
+    @Override
+    public void onItemClick(RemoteServer server) {
+        Intent intent = new Intent(this, MainActivity.class);
+        intent.putExtra("remote_server", server);
+        startActivity(intent);
+    }
+
+    private void showAddServerDialog() {
+        AlertDialog.Builder builder = new AlertDialog.Builder(this);
+        builder.setTitle("Add FTP Server");
+
+        LinearLayout layout = new LinearLayout(this);
+        layout.setOrientation(LinearLayout.VERTICAL);
+        layout.setPadding(50, 50, 50, 50);
+
+        final EditText hostInput = new EditText(this);
+        hostInput.setHint("Host");
+        layout.addView(hostInput);
+
+        final EditText portInput = new EditText(this);
+        portInput.setHint("Port (default: 21)");
+        portInput.setInputType(InputType.TYPE_CLASS_NUMBER);
+        layout.addView(portInput);
+
+        final EditText usernameInput = new EditText(this);
+        usernameInput.setHint("Username");
+        layout.addView(usernameInput);
+
+        final EditText passwordInput = new EditText(this);
+        passwordInput.setHint("Password");
+        passwordInput.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
+        layout.addView(passwordInput);
+
+        builder.setView(layout);
+
+        builder.setPositiveButton("Save", (dialog, which) -> {
+            String host = hostInput.getText().toString();
+            int port = portInput.getText().toString().isEmpty() ? 21 : Integer.parseInt(portInput.getText().toString());
+            String username = usernameInput.getText().toString();
+            String password = passwordInput.getText().toString();
+
+            RemoteServer server = new RemoteServer(0, host, port, username, password);
+            dbHelper.addServer(server);
+
+            // Refresh the list
+            serverList.clear();
+            serverList.addAll(dbHelper.getAllServers());
+            adapter.notifyDataSetChanged();
+        });
+        builder.setNegativeButton("Cancel", (dialog, which) -> dialog.cancel());
+
+        builder.show();
+    }
+}

app/src/main/res/drawable/ic_add.xml

@@ -0,0 +1,10 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M19,13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z"/>
+</vector>

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>

app/src/main/res/drawable/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>

app/src/main/res/layout/activity_remote_storage.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
+    tools:context=".RemoteStorageActivity">
+
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/remote_storage_recycler_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
+        android:id="@+id/fab_add_remote_storage"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom|end"
+        android:layout_margin="16dp"
+        android:src="@drawable/ic_add"
+        app:backgroundTint="@color/purple_500"
+        app:tint="@android:color/white"/>
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>

app/src/main/res/layout/list_item_remote_server.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical"
+    android:padding="16dp">
+
+    <TextView
+        android:id="@+id/server_host"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textSize="16sp"
+        android:textStyle="bold" />
+
+    <TextView
+        android:id="@+id/server_username"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content" />
+
+</LinearLayout>

app/src/main/res/menu/main_menu.xml

@@ -6,4 +6,9 @@
         android:title="Select Storage"
         android:icon="@drawable/ic_storage"
         app:showAsAction="ifRoom" />
+
+    <item
+        android:id="@+id/remote_storage"
+        android:title="Remote Storage"
+        app:showAsAction="never" />
 </menu>

app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,6 @@
+<?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" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,6 @@
+<?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" />
+    <monochrome android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

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_sFileExplorer" 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">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>

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>

app/src/main/res/values/strings.xml

@@ -0,0 +1,3 @@
+<resources>
+    <string name="app_name">Gyub_s File Explorer</string>
+</resources>

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_sFileExplorer" parent="Theme.MaterialComponents.DayNight.NoActionBar">
+        <!-- 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">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>

app/src/main/res/xml/backup_rules.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample backup rules file; uncomment and customize as necessary.
+   See https://developer.android.com/guide/topics/data/autobackup
+   for details.
+   Note: This file is ignored for devices older than API 31
+   See https://developer.android.com/about/versions/12/backup-restore
+-->
+<full-backup-content>
+    <!--
+   <include domain="sharedpref" path="."/>
+   <exclude domain="sharedpref" path="device.xml"/>
+-->
+</full-backup-content>

app/src/main/res/xml/data_extraction_rules.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+   Sample data extraction rules file; uncomment and customize as necessary.
+   See https://developer.android.com/about/versions/12/backup-restore#xml-changes
+   for details.
+-->
+<data-extraction-rules>
+    <cloud-backup>
+        <!-- TODO: Use <include> and <exclude> to control what is backed up.
+        <include .../>
+        <exclude .../>
+        -->
+    </cloud-backup>
+    <!--
+    <device-transfer>
+        <include .../>
+        <exclude .../>
+    </device-transfer>
+    -->
+</data-extraction-rules>

app/src/test/java/be/gyu/android/file/explorer/ExampleUnitTest.java

@@ -0,0 +1,17 @@
+package be.gyu.android.file.explorer;
+
+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);
+    }
+}