初级相册应用。

app/build.gradle

@@ -17,10 +17,20 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+    
+    buildFeatures {
+        viewBinding true
+    }
 }
 
 dependencies {
     implementation 'androidx.appcompat:appcompat:1.0.0'
 	implementation 'com.google.android.material:material:1.0.0'
+    implementation 'androidx.recyclerview:recyclerview:1.1.0'
+    implementation 'androidx.cardview:cardview:1.0.0'
+    implementation 'androidx.viewpager:viewpager:1.0.0'
+    implementation 'com.github.bumptech.glide:glide:4.12.0'
+    annotationProcessor 'com.github.bumptech.glide:compiler:4.12.0'
+    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
     implementation fileTree(dir: 'libs', include: ['*.jar'])
 }

app/src/main/AndroidManifest.xml

@@ -3,6 +3,9 @@
     xmlns:android="http://schemas.android.com/apk/res/android"
     package="cc.winboll.gallery">
 
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
+
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
@@ -26,6 +29,18 @@
 
         </activity>
 
+        <activity
+            android:name=".SettingsActivity"
+            android:label="@string/settings_title"/>
+
+        <activity
+            android:name=".AlbumActivity"
+            android:label="@string/app_name"/>
+
+        <activity
+            android:name=".ImageViewerActivity"
+            android:label="@string/app_name"/>
+
         <meta-data
             android:name="android.max_aspect"
             android:value="4.0"/>

app/src/main/java/cc/winboll/gallery/Album.java

@@ -0,0 +1,22 @@
+package cc.winboll.gallery;
+
+import android.net.Uri;
+
+public class Album {
+    private String name;
+    private String path;
+    private Uri coverUri;
+    private int imageCount;
+
+    public Album(String name, String path, Uri coverUri, int imageCount) {
+        this.name = name;
+        this.path = path;
+        this.coverUri = coverUri;
+        this.imageCount = imageCount;
+    }
+
+    public String getName() { return name; }
+    public String getPath() { return path; }
+    public Uri getCoverUri() { return coverUri; }
+    public int getImageCount() { return imageCount; }
+}

app/src/main/java/cc/winboll/gallery/AlbumActivity.java

@@ -0,0 +1,131 @@
+package cc.winboll.gallery;
+
+import android.content.ContentResolver;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.Bundle;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.widget.Toast;
+import androidx.annotation.NonNull;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.Toolbar;
+import androidx.core.app.ActivityCompat;
+import androidx.core.content.ContextCompat;
+import androidx.recyclerview.widget.GridLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import java.util.ArrayList;
+
+public class AlbumActivity extends AppCompatActivity {
+    private static final int PERMISSION_REQUEST_CODE = 101;
+    public static final String EXTRA_ALBUM_PATH = "album_path";
+    public static final String EXTRA_ALBUM_NAME = "album_name";
+    private RecyclerView recyclerView;
+    private ImageAdapter adapter;
+    private String albumPath;
+    private String albumName;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+        
+        Toolbar toolbar = findViewById(R.id.toolbar);
+        setSupportActionBar(toolbar);
+        
+        albumPath = getIntent().getStringExtra(EXTRA_ALBUM_PATH);
+        albumName = getIntent().getStringExtra(EXTRA_ALBUM_NAME);
+        
+        getSupportActionBar().setTitle(albumName);
+        
+        recyclerView = findViewById(R.id.recycler_view);
+        recyclerView.setLayoutManager(new GridLayoutManager(this, 3));
+        adapter = new ImageAdapter();
+        recyclerView.setAdapter(adapter);
+        
+        adapter.setOnImageClickListener((position, urls) -> {
+            Intent intent = new Intent(this, ImageViewerActivity.class);
+            intent.putParcelableArrayListExtra(ImageViewerActivity.EXTRA_IMAGE_URLS, urls);
+            intent.putExtra(ImageViewerActivity.EXTRA_POSITION, position);
+            startActivity(intent);
+        });
+        
+        if (checkPermission()) {
+            loadImages();
+        } else {
+            requestPermission();
+        }
+    }
+
+    private boolean checkPermission() {
+        return ContextCompat.checkSelfPermission(this, android.Manifest.permission.READ_EXTERNAL_STORAGE) 
+            == PackageManager.PERMISSION_GRANTED;
+    }
+
+    private void requestPermission() {
+        ActivityCompat.requestPermissions(this, 
+            new String[]{android.Manifest.permission.READ_EXTERNAL_STORAGE}, 
+            PERMISSION_REQUEST_CODE);
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, 
+            @NonNull int[] grantResults) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        if (requestCode == PERMISSION_REQUEST_CODE) {
+            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                loadImages();
+            } else {
+                Toast.makeText(this, "Permission denied", Toast.LENGTH_SHORT).show();
+            }
+        }
+    }
+
+    private void loadImages() {
+        ArrayList<Uri> imageUrls = new ArrayList<>();
+        ContentResolver contentResolver = getContentResolver();
+        Uri collection = android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
+        
+        String selection = android.provider.MediaStore.Images.Media.DATA + " LIKE ?";
+        String[] selectionArgs = new String[]{albumPath + "%"};
+        String sortOrder = android.provider.MediaStore.Images.Media.DATE_ADDED + " DESC";
+        
+        try (Cursor cursor = contentResolver.query(collection, null, selection, selectionArgs, sortOrder)) {
+            if (cursor != null) {
+                int dataColumn = cursor.getColumnIndexOrThrow(android.provider.MediaStore.Images.Media.DATA);
+                while (cursor.moveToNext()) {
+                    String path = cursor.getString(dataColumn);
+                    if (path != null && path.startsWith(albumPath + "/")) {
+                        long id = cursor.getLong(cursor.getColumnIndexOrThrow(android.provider.MediaStore.Images.Media._ID));
+                        Uri contentUri = Uri.withAppendedPath(collection, String.valueOf(id));
+                        imageUrls.add(contentUri);
+                    }
+                }
+            }
+        }
+        
+        if (imageUrls.isEmpty()) {
+            Toast.makeText(this, R.string.no_images_found, Toast.LENGTH_SHORT).show();
+        }
+        adapter.setData(imageUrls);
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.menu_main, menu);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
+        if (item.getItemId() == R.id.action_refresh) {
+            if (checkPermission()) {
+                loadImages();
+            }
+            return true;
+        }
+        return super.onOptionsItemSelected(item);
+    }
+}

app/src/main/java/cc/winboll/gallery/AlbumAdapter.java

@@ -0,0 +1,71 @@
+package cc.winboll.gallery;
+
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import android.widget.TextView;
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+import com.bumptech.glide.Glide;
+import java.util.ArrayList;
+
+public class AlbumAdapter extends RecyclerView.Adapter<AlbumAdapter.ViewHolder> {
+    private ArrayList<Album> albums = new ArrayList<>();
+    private OnAlbumClickListener listener;
+
+    public interface OnAlbumClickListener {
+        void onAlbumClick(Album album);
+    }
+
+    public void setOnAlbumClickListener(OnAlbumClickListener listener) {
+        this.listener = listener;
+    }
+
+    public void setData(ArrayList<Album> albums) {
+        this.albums = albums;
+        notifyDataSetChanged();
+    }
+
+    @NonNull
+    @Override
+    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        View view = LayoutInflater.from(parent.getContext())
+            .inflate(R.layout.item_album, parent, false);
+        return new ViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
+        Album album = albums.get(position);
+        Glide.with(holder.coverImage.getContext())
+            .load(album.getCoverUri())
+            .centerCrop()
+            .into(holder.coverImage);
+        holder.albumName.setText(album.getName());
+        holder.imageCount.setText(album.getImageCount() + " photos");
+        
+        holder.itemView.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onAlbumClick(album);
+            }
+        });
+    }
+
+    @Override
+    public int getItemCount() {
+        return albums.size();
+    }
+
+    static class ViewHolder extends RecyclerView.ViewHolder {
+        ImageView coverImage;
+        TextView albumName;
+        TextView imageCount;
+        ViewHolder(View itemView) {
+            super(itemView);
+            coverImage = itemView.findViewById(R.id.album_cover);
+            albumName = itemView.findViewById(R.id.album_name);
+            imageCount = itemView.findViewById(R.id.image_count);
+        }
+    }
+}

app/src/main/java/cc/winboll/gallery/ImageAdapter.java

@@ -0,0 +1,65 @@
+package cc.winboll.gallery;
+
+import android.content.Intent;
+import android.net.Uri;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import androidx.annotation.NonNull;
+import androidx.recyclerview.widget.RecyclerView;
+import com.bumptech.glide.Glide;
+import java.util.ArrayList;
+
+public class ImageAdapter extends RecyclerView.Adapter<ImageAdapter.ViewHolder> {
+    private ArrayList<Uri> imageUrls = new ArrayList<>();
+    private OnImageClickListener listener;
+
+    public interface OnImageClickListener {
+        void onImageClick(int position, ArrayList<Uri> urls);
+    }
+
+    public void setOnImageClickListener(OnImageClickListener listener) {
+        this.listener = listener;
+    }
+
+    public void setData(ArrayList<Uri> urls) {
+        this.imageUrls = urls;
+        notifyDataSetChanged();
+    }
+
+    @NonNull
+    @Override
+    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+        View view = LayoutInflater.from(parent.getContext())
+            .inflate(R.layout.item_gallery, parent, false);
+        return new ViewHolder(view);
+    }
+
+    @Override
+    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
+        Glide.with(holder.imageView.getContext())
+            .load(imageUrls.get(position))
+            .centerCrop()
+            .into(holder.imageView);
+        
+        holder.imageView.setOnClickListener(v -> {
+            if (listener != null) {
+                listener.onImageClick(position, imageUrls);
+            }
+        });
+    }
+
+    @Override
+    public int getItemCount() {
+        return imageUrls.size();
+    }
+
+    static class ViewHolder extends RecyclerView.ViewHolder {
+        ImageView imageView;
+        ViewHolder(View itemView) {
+            super(itemView);
+            imageView = itemView.findViewById(R.id.image);
+        }
+    }
+}

app/src/main/java/cc/winboll/gallery/ImagePagerAdapter.java

@@ -0,0 +1,52 @@
+package cc.winboll.gallery;
+
+import android.net.Uri;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import androidx.annotation.NonNull;
+import androidx.viewpager.widget.PagerAdapter;
+import com.bumptech.glide.Glide;
+import com.bumptech.glide.load.engine.DiskCacheStrategy;
+import java.util.ArrayList;
+
+public class ImagePagerAdapter extends PagerAdapter {
+    private ArrayList<Uri> imageUrls;
+
+    public ImagePagerAdapter(ArrayList<Uri> imageUrls) {
+        this.imageUrls = imageUrls;
+    }
+
+    @Override
+    public int getCount() {
+        return imageUrls.size();
+    }
+
+    @NonNull
+    @Override
+    public Object instantiateItem(@NonNull ViewGroup container, int position) {
+        View view = LayoutInflater.from(container.getContext())
+            .inflate(R.layout.item_image_pager, container, false);
+        ImageView imageView = view.findViewById(R.id.image);
+        
+        Glide.with(imageView.getContext())
+            .load(imageUrls.get(position))
+            .diskCacheStrategy(DiskCacheStrategy.NONE)
+            .skipMemoryCache(true)
+            .into(imageView);
+        
+        container.addView(view);
+        return view;
+    }
+
+    @Override
+    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
+        container.removeView((View) object);
+    }
+
+    @Override
+    public boolean isViewFromObject(@NonNull View view, @NonNull Object object) {
+        return view == object;
+    }
+}

app/src/main/java/cc/winboll/gallery/ImageViewerActivity.java

@@ -0,0 +1,73 @@
+package cc.winboll.gallery;
+
+import android.app.Activity;
+import android.net.Uri;
+import android.os.Bundle;
+import android.view.View;
+import android.view.WindowManager;
+import android.widget.ImageButton;
+import androidx.viewpager.widget.ViewPager;
+import java.util.ArrayList;
+
+public class ImageViewerActivity extends Activity implements ViewPager.OnPageChangeListener {
+    public static final String EXTRA_IMAGE_URLS = "image_urls";
+    public static final String EXTRA_POSITION = "position";
+    
+    private ArrayList<Uri> imageUrls;
+    private int currentPosition;
+    private ViewPager viewPager;
+    private View toolbar;
+    private ImageButton btnBack;
+    
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
+            WindowManager.LayoutParams.FLAG_FULLSCREEN);
+        setContentView(R.layout.activity_image_viewer);
+        
+        imageUrls = getIntent().getParcelableArrayListExtra(EXTRA_IMAGE_URLS);
+        currentPosition = getIntent().getIntExtra(EXTRA_POSITION, 0);
+        
+        viewPager = findViewById(R.id.view_pager);
+        toolbar = findViewById(R.id.toolbar);
+        btnBack = findViewById(R.id.btn_back);
+        
+        ImagePagerAdapter adapter = new ImagePagerAdapter(imageUrls);
+        viewPager.setAdapter(adapter);
+        viewPager.setCurrentItem(currentPosition);
+        viewPager.addOnPageChangeListener(this);
+        
+        btnBack.setOnClickListener(v -> finish());
+        
+        viewPager.setOnClickListener(v -> toggleToolbar());
+    }
+    
+    private void toggleToolbar() {
+        if (toolbar.getVisibility() == View.VISIBLE) {
+            toolbar.setVisibility(View.GONE);
+        } else {
+            toolbar.setVisibility(View.VISIBLE);
+        }
+    }
+    
+    @Override
+    public void onPageSelected(int position) {
+        currentPosition = position;
+    }
+    
+    @Override
+    public void onPageScrollStateChanged(int state) {}
+    
+    @Override
+    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}
+    
+    @Override
+    public void onBackPressed() {
+        if (viewPager.getCurrentItem() > 0) {
+            viewPager.setCurrentItem(viewPager.getCurrentItem() - 1);
+        } else {
+            super.onBackPressed();
+        }
+    }
+}

app/src/main/java/cc/winboll/gallery/MainActivity.java

@@ -1,19 +1,169 @@
 package cc.winboll.gallery;
 
+import android.Manifest;
+import android.content.ContentResolver;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.database.Cursor;
+import android.net.Uri;
 import android.os.Bundle;
+import android.os.Environment;
+import android.provider.MediaStore;
+import android.view.Menu;
+import android.view.MenuItem;
+import android.widget.Toast;
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
+import androidx.core.app.ActivityCompat;
+import androidx.core.content.ContextCompat;
+import androidx.recyclerview.widget.GridLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
+import java.io.File;
+import java.util.ArrayList;
 
 public class MainActivity extends AppCompatActivity {
+    private static final int PERMISSION_REQUEST_CODE = 100;
+    private RecyclerView recyclerView;
+    private AlbumAdapter adapter;
+    private Preferences prefs;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         
-		Toolbar toolbar=(Toolbar)findViewById(R.id.toolbar);
+        Toolbar toolbar = findViewById(R.id.toolbar);
         setSupportActionBar(toolbar);
         
+        prefs = new Preferences(this);
+        
+        recyclerView = findViewById(R.id.recycler_view);
+        recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
+        adapter = new AlbumAdapter();
+        recyclerView.setAdapter(adapter);
+        
+        adapter.setOnAlbumClickListener(album -> {
+            Intent intent = new Intent(this, AlbumActivity.class);
+            intent.putExtra(AlbumActivity.EXTRA_ALBUM_PATH, album.getPath());
+            intent.putExtra(AlbumActivity.EXTRA_ALBUM_NAME, album.getName());
+            startActivity(intent);
+        });
+        
+        if (checkPermission()) {
+            loadAlbums();
+        } else {
+            requestPermission();
+        }
     }
 
+    private boolean checkPermission() {
+        return ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) 
+            == PackageManager.PERMISSION_GRANTED;
+    }
+
+    private void requestPermission() {
+        ActivityCompat.requestPermissions(this, 
+            new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 
+            PERMISSION_REQUEST_CODE);
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, 
+            @NonNull int[] grantResults) {
+        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
+        if (requestCode == PERMISSION_REQUEST_CODE) {
+            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                loadAlbums();
+            } else {
+                Toast.makeText(this, "Permission denied", Toast.LENGTH_SHORT).show();
+            }
+        }
+    }
+
+    private void loadAlbums() {
+        String folderPath = prefs.getFolderPath();
+        File baseFolder = new File(folderPath);
+        
+        if (!baseFolder.exists() || !baseFolder.isDirectory()) {
+            folderPath = Environment.getExternalStorageDirectory() + "/DCIM";
+            baseFolder = new File(folderPath);
+            if (!baseFolder.exists()) {
+                folderPath = Environment.getExternalStorageDirectory() + "/Pictures";
+                baseFolder = new File(folderPath);
+            }
+        }
+        
+        ArrayList<Album> albums = new ArrayList<>();
+        
+        File[] subfolders = baseFolder.listFiles(File::isDirectory);
+        if (subfolders != null) {
+            for (File subfolder : subfolders) {
+                ArrayList<Uri> images = getImagesInFolder(subfolder.getAbsolutePath());
+                if (!images.isEmpty()) {
+                    Uri latestImage = images.get(0);
+                    albums.add(new Album(subfolder.getName(), subfolder.getAbsolutePath(), latestImage, images.size()));
+                }
+            }
+        }
+        
+        if (albums.isEmpty()) {
+            Toast.makeText(this, R.string.no_images_found, Toast.LENGTH_SHORT).show();
+        }
+        adapter.setData(albums);
+    }
+
+    private ArrayList<Uri> getImagesInFolder(String folderPath) {
+        ArrayList<Uri> imageUrls = new ArrayList<>();
+        ContentResolver contentResolver = getContentResolver();
+        Uri collection = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
+        
+        String selection = MediaStore.Images.Media.DATA + " LIKE ?";
+        String[] selectionArgs = new String[]{folderPath + "/%"};
+        String sortOrder = MediaStore.Images.Media.DATE_ADDED + " DESC";
+        
+        try (Cursor cursor = contentResolver.query(collection, null, selection, selectionArgs, sortOrder)) {
+            if (cursor != null) {
+                int dataColumn = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
+                while (cursor.moveToNext()) {
+                    String path = cursor.getString(dataColumn);
+                    if (path != null) {
+                        long id = cursor.getLong(cursor.getColumnIndexOrThrow(MediaStore.Images.Media._ID));
+                        Uri contentUri = Uri.withAppendedPath(collection, String.valueOf(id));
+                        imageUrls.add(contentUri);
+                    }
+                }
+            }
+        }
+        return imageUrls;
+    }
+
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        getMenuInflater().inflate(R.menu.menu_main, menu);
+        return true;
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
+        int id = item.getItemId();
+        if (id == R.id.action_settings) {
+            startActivity(new Intent(this, SettingsActivity.class));
+            return true;
+        } else if (id == R.id.action_refresh) {
+            if (checkPermission()) {
+                loadAlbums();
+            }
+            return true;
+        }
+        return super.onOptionsItemSelected(item);
+    }
+    
+    @Override
+    protected void onResume() {
+        super.onResume();
+        if (checkPermission()) {
+            loadAlbums();
+        }
+    }
 }

app/src/main/java/cc/winboll/gallery/Preferences.java

@@ -0,0 +1,28 @@
+package cc.winboll.gallery;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+
+public class Preferences {
+    private static final String PREF_NAME = "gallery_prefs";
+    private static final String KEY_FOLDER_PATH = "folder_path";
+    private static final String DEFAULT_PATH = "/storage/emulated/0/DCIM";
+    
+    public static String getDefaultPath() {
+        return DEFAULT_PATH;
+    }
+    
+    private final SharedPreferences prefs;
+    
+    public Preferences(Context context) {
+        prefs = context.getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
+    }
+    
+    public String getFolderPath() {
+        return prefs.getString(KEY_FOLDER_PATH, DEFAULT_PATH);
+    }
+    
+    public void setFolderPath(String path) {
+        prefs.edit().putString(KEY_FOLDER_PATH, path).apply();
+    }
+}

app/src/main/java/cc/winboll/gallery/SettingsActivity.java

@@ -0,0 +1,38 @@
+package cc.winboll.gallery;
+
+import android.os.Bundle;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.TextView;
+import androidx.appcompat.app.AppCompatActivity;
+
+public class SettingsActivity extends AppCompatActivity {
+    private Preferences prefs;
+    private EditText editFolderPath;
+    private TextView textCurrentPath;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_settings);
+        
+        prefs = new Preferences(this);
+        
+        editFolderPath = findViewById(R.id.edit_folder_path);
+        textCurrentPath = findViewById(R.id.text_current_path);
+        Button btnSave = findViewById(R.id.btn_save);
+        
+        String currentPath = prefs.getFolderPath();
+        editFolderPath.setText(currentPath);
+        textCurrentPath.setText("Current: " + currentPath);
+        
+        btnSave.setOnClickListener(v -> {
+            String newPath = editFolderPath.getText().toString().trim();
+            if (!newPath.isEmpty()) {
+                prefs.setFolderPath(newPath);
+                textCurrentPath.setText("Current: " + newPath);
+            }
+            finish();
+        });
+    }
+}

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

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FFFFFF"
+        android:pathData="M20,11H7.83l5.59,-5.59L12,4l-8,8 8,8 1.41,-1.41L7.83,13H20v-2z"/>
+</vector>

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

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@color/black">
+
+    <androidx.viewpager.widget.ViewPager
+        android:id="@+id/view_pager"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"/>
+
+    <LinearLayout
+        android:id="@+id/toolbar"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_gravity="top"
+        android:background="#CC000000"
+        android:orientation="horizontal"
+        android:padding="8dp">
+
+        <ImageButton
+            android:id="@+id/btn_back"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:background="?attr/selectableItemBackgroundBorderless"
+            android:src="@drawable/ic_back"
+            android:contentDescription="Back"/>
+
+    </LinearLayout>
+
+</FrameLayout>

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

@@ -19,4 +19,10 @@
 
     </com.google.android.material.appbar.AppBarLayout>
 
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/recycler_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:background="@color/black"/>
+
 </LinearLayout>

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

@@ -0,0 +1,39 @@
+<?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="match_parent"
+    android:orientation="vertical"
+    android:padding="16dp">
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/folder_path"
+        android:textSize="16sp"
+        android:textStyle="bold"/>
+
+    <EditText
+        android:id="@+id/edit_folder_path"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:hint="@string/enter_folder_path"
+        android:inputType="text"/>
+
+    <TextView
+        android:id="@+id/text_current_path"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="8dp"
+        android:textSize="12sp"
+        android:textColor="#888888"/>
+
+    <Button
+        android:id="@+id/btn_save"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="16dp"
+        android:text="@string/save"/>
+
+</LinearLayout>

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

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:padding="2dp">
+
+    <ImageView
+        android:id="@+id/album_cover"
+        android:layout_width="match_parent"
+        android:layout_height="120dp"
+        android:scaleType="centerCrop"
+        android:background="@color/black"/>
+
+    <TextView
+        android:id="@+id/album_name"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom"
+        android:background="#80000000"
+        android:padding="4dp"
+        android:textColor="@color/white"
+        android:textSize="12sp"
+        android:maxLines="1"
+        android:ellipsize="end"/>
+
+    <TextView
+        android:id="@+id/image_count"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="top|end"
+        android:background="#80000000"
+        android:padding="4dp"
+        android:textColor="@color/white"
+        android:textSize="10sp"/>
+
+</FrameLayout>

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

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:padding="2dp">
+
+    <ImageView
+        android:id="@+id/image"
+        android:layout_width="match_parent"
+        android:layout_height="120dp"
+        android:scaleType="centerCrop"
+        android:background="@color/black"/>
+
+</FrameLayout>

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

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@color/black">
+
+    <ImageView
+        android:id="@+id/image"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:scaleType="fitCenter"/>
+
+</FrameLayout>

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

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+    
+    <item
+        android:id="@+id/action_settings"
+        android:title="@string/settings"
+        app:showAsAction="never"/>
+    
+    <item
+        android:id="@+id/action_refresh"
+        android:title="@string/refresh"
+        app:showAsAction="never"/>
+    
+</menu>

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

@@ -3,4 +3,6 @@
     <color name="colorPrimary">#009688</color>
     <color name="colorPrimaryDark">#00796B</color>
     <color name="colorAccent">#FF9800</color>
+    <color name="black">#000000</color>
+    <color name="white">#FFFFFF</color>
 </resources>

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

@@ -1,4 +1,11 @@
 <resources>
     <string name="app_name">Gallery</string>
-    
+    <string name="refresh">Refresh</string>
+    <string name="settings">Settings</string>
+    <string name="settings_title">Settings</string>
+    <string name="folder_path">Folder Path</string>
+    <string name="enter_folder_path">Enter folder path</string>
+    <string name="save">Save</string>
+    <string name="cancel">Cancel</string>
+    <string name="no_images_found">No images found</string>
 </resources>

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.5-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

local.properties

@@ -7,4 +7,4 @@
 # Location of the SDK. This is only used by Gradle.
 # For customization when using a Version Control System, please read the
 # header note.
-#sdk.dir=
+sdk.dir=/home/jian/Android/Sdk