android app调用系统相机后拍照，将照片路径信息存到数据库，并在recyclerview显示拍到的照片

实现这个功能需要以下几个步骤：

1. 在 AndroidManifest.xml 文件中添加相机和文件读写权限。

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

2. 创建一个拍照按钮，并在点击事件中调用系统相机。

// 启动系统相机
public void startCamera() {
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    if (intent.resolveActivity(getPackageManager()) != null) {
        File photoFile = createImageFile();
        if (photoFile != null) {
            Uri photoUri = FileProvider.getUriForFile(this, "com.example.fileprovider", photoFile);
            intent.putExtra(MediaStore.EXTRA_OUTPUT, photoUri);
            startActivityForResult(intent, REQUEST_CODE_CAMERA);
        }
    }
}

// 创建图片文件
public File createImageFile() {
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    try {
        File imageFile = File.createTempFile(imageFileName, ".jpg", storageDir);
        mCurrentPhotoPath = imageFile.getAbsolutePath();
        return imageFile;
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

// 处理拍照结果
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CODE_CAMERA && resultCode == RESULT_OK) {
        String photoPath = mCurrentPhotoPath;
        savePhotoPath(photoPath); // 将照片路径保存到数据库
        mAdapter.addData(photoPath); // 将照片路径添加到 RecyclerView 中显示
    }
}

3. 在 Activity 中创建一个 RecyclerView，并通过 Adapter 将数据绑定到 RecyclerView 上。

// 初始化 RecyclerView
public void initRecyclerView() {
    mRecyclerView = findViewById(R.id.recyclerview);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
    mAdapter = new PhotoAdapter(this);
    mRecyclerView.setAdapter(mAdapter);
}

// 创建 Adapter
public class PhotoAdapter extends RecyclerView.Adapter<PhotoAdapter.ViewHolder> {
    private Context mContext;
    private List<String> mPhotoPaths;

    public PhotoAdapter(Context context) {
        mContext = context;
        mPhotoPaths = new ArrayList<>();
    }

    public void setData(List<String> photoPaths) {
        mPhotoPaths.clear();
        mPhotoPaths.addAll(photoPaths);
        notifyDataSetChanged();
    }

    public void addData(String photoPath) {
        mPhotoPaths.add(0, photoPath);
        notifyItemInserted(0);
        mRecyclerView.scrollToPosition(0);
    }

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

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        String photoPath = mPhotoPaths.get(position);
        Glide.with(mContext).load(photoPath).into(holder.ivPhoto);
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        ImageView ivPhoto;

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

4. 将拍摄的照片路径保存到数据库中。

// 将照片路径保存到数据库
public void savePhotoPath(String photoPath) {
    SQLiteDatabase db = mDbHelper.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(PhotoEntry.COLUMN_NAME_PATH, photoPath);
    db.insert(PhotoEntry.TABLE_NAME, null, values);
    db.close();
}

5. 在 Activity 的 onCreate() 方法中初始化 RecyclerView 和数据库。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initRecyclerView();
    mDbHelper = new PhotoDbHelper(this);
    loadPhotoPaths(); // 从数据库中加载照片路径并显示到 RecyclerView 上
}

6. 从数据库中加载照片路径并显示到 RecyclerView 上。

// 从数据库中加载照片路径并显示到 RecyclerView 上
public void loadPhotoPaths() {
    SQLiteDatabase db = mDbHelper.getReadableDatabase();
    String[] projection = {
            PhotoEntry._ID,
            PhotoEntry.COLUMN_NAME_PATH
    };
    Cursor cursor = db.query(
            PhotoEntry.TABLE_NAME,
            projection,
            null,
            null,
            null,
            null,
            PhotoEntry._ID + " DESC"
    );
    List<String> photoPaths = new ArrayList<>();
    while (cursor.moveToNext()) {
        String photoPath = cursor.getString(cursor.getColumnIndexOrThrow(PhotoEntry.COLUMN_NAME_PATH));
        photoPaths.add(photoPath);
    }
    mAdapter.setData(photoPaths);
    cursor.close();
    db.close();
}

这样就可以实现在 Android App 中调用系统相机后拍照，将照片路径信息存到数据库，并在 RecyclerView 显示拍到的照片。