如何在android代码中同时打开手电筒（闪光灯）和后置摄像头

Question

当我打开闪光灯时。如果我使用 camera.release() 方法将相机用于后置相机图像，则相机会停止，闪光灯会关闭。

switch1.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
    @SuppressLint("MissingPermission")
    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        if (isChecked) {
            camera = Camera.open(); // for camera on purpose
            Camera.Parameters para = camera.getParameters();
            para.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
            camera.setParameters(para);
            camera.startPreview();
            cameraSource.release();
            camera = null;
            try {
                cameraSource.start(surfaceView.getHolder());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
});

      //   when I turned on the flash. the camera stops if I use camera.release() method to use the camera for back camera image taking the flash turns off.  

Answer 1

在 API 23 或更高版本中

这就是你开启的方式

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
    CameraManager camManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    String cameraId = null; 
    try {
        cameraId = camManager.getCameraIdList()[0];
        camManager.setTorchMode(cameraId, true);   //Turn ON
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

这是关闭的方式

camManager.setTorchMode(cameraId, false);

需要的权限

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

完整的实现可能如下所示

public class CameraAndFlashProvider {

private static final String TAG = FlashlightProvider.class.getSimpleName();
private Camera mCamera;
private Camera.Parameters parameters;
private CameraManager camManager;
private Context context;

public CameraAndFlashProvider(Context context) {
    this.context = context;
}

private void turnFlashlightOn() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        try {
            camManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
            String cameraId = null; 
            if (camManager != null) {
                cameraId = camManager.getCameraIdList()[0];
                camManager.setTorchMode(cameraId, true);
            }
        } catch (CameraAccessException e) {
            Log.e(TAG, e.toString());
        }
    } else {
        mCamera = Camera.open();
        parameters = mCamera.getParameters();
        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
        mCamera.setParameters(parameters);
        mCamera.startPreview();
    }
}

private void turnFlashlightOff() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        try {
            String cameraId;
            camManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
            if (camManager != null) {
                cameraId = camManager.getCameraIdList()[0]; // Usually front camera is at 0 position.
                camManager.setTorchMode(cameraId, false);
            }
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    } else {
        mCamera = Camera.open();
        parameters = mCamera.getParameters();
        parameters.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
        mCamera.setParameters(parameters);
        mCamera.stopPreview();
    }
}
}