android studio 拍照

在Android Studio中拍照有两种方式：使用Camera API和使用CameraX API。

使用Camera API：

1. 添加权限到AndroidManifest.xml文件：

<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.CAMERA" />

2. 在布局文件中添加一个SurfaceView或TextureView：

<SurfaceView
    android:id="@+id/surfaceView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

3. 在Activity或Fragment中添加以下代码：

private Camera camera;
private SurfaceView surfaceView;

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

    surfaceView = findViewById(R.id.surfaceView);
    surfaceView.getHolder().addCallback(surfaceCallback);
}

private SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        camera = Camera.open();
        try {
            camera.setPreviewDisplay(holder);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        Camera.Parameters parameters = camera.getParameters();
        parameters.setPreviewSize(width, height);
        camera.setParameters(parameters);
        camera.startPreview();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        camera.stopPreview();
        camera.release();
        camera = null;
    }
};

public void takePicture(View view) {
    camera.takePicture(null, null, pictureCallback);
}

private Camera.PictureCallback pictureCallback = new Camera.PictureCallback() {
    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
        //处理拍照数据
    }
};

4. 在布局文件中添加一个按钮，并在Activity或Fragment中实现按钮的点击事件：

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Take Picture"
    android:onClick="takePicture" />

使用CameraX API：

1. 添加依赖到build.gradle文件：

dependencies {
    def camerax_version = "1.0.0"

    // CameraX core library
    implementation "androidx.camera:camera-core:$camerax_version"

    // CameraX Camera2 extensions
    implementation "androidx.camera:camera-camera2:$camerax_version"

    // CameraX Lifecycle library
    implementation "androidx.camera:camera-lifecycle:$camerax_version"

    // CameraX View class
    implementation "androidx.camera:camera-view:1.0.0-alpha23"
}

2. 在布局文件中添加一个PreviewView：

<androidx.camera.view.PreviewView
    android:id="@+id/previewView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

3. 在Activity或Fragment中添加以下代码：

private ListenableFuture<ProcessCameraProvider> cameraProviderFuture;
private Preview preview;
private ImageCapture imageCapture;

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

    cameraProviderFuture = ProcessCameraProvider.getInstance(this);
    cameraProviderFuture.addListener(() -> {
        try {
            ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
            preview = new Preview.Builder().build();
            preview.setSurfaceProvider(previewView.createSurfaceProvider());
            imageCapture = new ImageCapture.Builder().build();
            cameraProvider.unbindAll();
            cameraProvider.bindToLifecycle(this, CameraSelector.DEFAULT_BACK_CAMERA, preview, imageCapture);
        } catch (ExecutionException | InterruptedException e) {
            e.printStackTrace();
        }
    }, ContextCompat.getMainExecutor(this));
}

public void takePicture(View view) {
    File file = new File(getExternalMediaDirs()[0], System.currentTimeMillis() + ".jpg");
    ImageCapture.OutputFileOptions outputFileOptions = new ImageCapture.OutputFileOptions.Builder(file).build();
    imageCapture.takePicture(outputFileOptions, ContextCompat.getMainExecutor(this), new ImageCapture.OnImageSavedCallback() {
        @Override
        public void onImageSaved(@NonNull ImageCapture.OutputFileResults outputFileResults) {
            //处理拍照数据
        }

        @Override
        public void onError(@NonNull ImageCaptureException exception) {
            exception.printStackTrace();
        }
    });
}

4. 在布局文件中添加一个按钮，并在Activity或Fragment中实现按钮的点击事件：

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Take Picture"
    android:onClick="takePicture" />