调用系统相机拍照，照片储存到数据库之中，并且获取相册路径，在recyclerview中显示出来

首先需要在AndroidManifest.xml文件中添加相机和存储权限：

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

然后创建一个布局文件activity_main.xml，包含一个按钮和一个RecyclerView：

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/btn_take_photo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Take photo"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_photos"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toTopOf="@+id/btn_take_photo"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

接下来创建一个Photo实体类，用于存储照片信息：

public class Photo {
    private int id;
    private String imagePath;

    public Photo(int id, String imagePath) {
        this.id = id;
        this.imagePath = imagePath;
    }

    public int getId() {
        return id;
    }

    public String getImagePath() {
        return imagePath;
    }
}

然后创建一个PhotosAdapter类，用于RecyclerView的显示：

public class PhotosAdapter extends RecyclerView.Adapter<PhotosAdapter.ViewHolder> {
    private List<Photo> photos;

    public PhotosAdapter(List<Photo> photos) {
        this.photos = photos;
    }

    public void setPhotos(List<Photo> photos) {
        this.photos = photos;
        notifyDataSetChanged();
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_photo, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Photo photo = photos.get(position);
        Glide.with(holder.itemView.getContext())
                .load(photo.getImagePath())
                .into(holder.ivPhoto);
    }

    @Override
    public int getItemCount() {
        return photos.size();
    }

    static class ViewHolder extends RecyclerView.ViewHolder {
        ImageView ivPhoto;

        ViewHolder(@NonNull View itemView) {
            super(itemView);
            ivPhoto = itemView.findViewById(R.id.iv_photo);
        }
    }
}

接下来创建一个MainActivity类，实现拍照、保存到数据库和显示相册的功能：

public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_CODE_TAKE_PHOTO = 1;

    private SQLiteDatabase db;
    private PhotosAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        db = new DBHelper(this).getWritableDatabase();
        adapter = new PhotosAdapter(new ArrayList<>());
        RecyclerView rvPhotos = findViewById(R.id.rv_photos);
        rvPhotos.setLayoutManager(new GridLayoutManager(this, 3));
        rvPhotos.setAdapter(adapter);

        Button btnTakePhoto = findViewById(R.id.btn_take_photo);
        btnTakePhoto.setOnClickListener(v -> {
            Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            if (intent.resolveActivity(getPackageManager()) != null) {
                startActivityForResult(intent, REQUEST_CODE_TAKE_PHOTO);
            }
        });

        showPhotos();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_CODE_TAKE_PHOTO && resultCode == RESULT_OK && data != null) {
            Bitmap bitmap = (Bitmap) data.getExtras().get("data");
            if (bitmap != null) {
                String imagePath = saveImage(bitmap);
                if (imagePath != null) {
                    addPhoto(imagePath);
                    showPhotos();
                } else {
                    Toast.makeText(this, "Failed to save image", Toast.LENGTH_SHORT).show();
                }
            } else {
                Toast.makeText(this, "Failed to get image", Toast.LENGTH_SHORT).show();
            }
        }
    }

    private String saveImage(Bitmap bitmap) {
        String fileName = "IMG_" + new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(new Date()) + ".jpg";
        File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), fileName);
        try (FileOutputStream fos = new FileOutputStream(file)) {
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            return file.getAbsolutePath();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    private void addPhoto(String imagePath) {
        ContentValues contentValues = new ContentValues();
        contentValues.put(DBHelper.COLUMN_IMAGE_PATH, imagePath);
        db.insert(DBHelper.TABLE_NAME, null, contentValues);
    }

    private void showPhotos() {
        List<Photo> photos = new ArrayList<>();
        Cursor cursor = db.query(DBHelper.TABLE_NAME, null, null, null, null, null, null);
        if (cursor.moveToFirst()) {
            do {
                int id = cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_ID));
                String imagePath = cursor.getString(cursor.getColumnIndex(DBHelper.COLUMN_IMAGE_PATH));
                photos.add(new Photo(id, imagePath));
            } while (cursor.moveToNext());
        }
        cursor.close();
        adapter.setPhotos(photos);
    }
}

最后在res文件夹下创建一个布局文件item_photo.xml，用于显示每个照片：

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:layout_margin="4dp"
    android:clickable="true"
    android:focusable="true"
    android:foreground="?android:attr/selectableItemBackground">

    <ImageView
        android:id="@+id/iv_photo"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="centerCrop" />

</androidx.cardview.widget.CardView>

这样就完成了调用系统相机拍照，照片储存到数据库之中，并且获取相册路径，在recyclerview中显示出来的功能。