使用Camera2 Api的LED手电筒有问题吗？

Question

I am trying to turn the flashlight on as the camera starts but here is what is actually happening. My flashlight turns on and then its goes off after a couple of milliseconds. I am really confused as what is causing that to happen. I am using the camera2 api and I am targeting devices with api >21 This is what I tried so far.

Answer 1

@InsaneCat is right ( see this link )

Remove your calls to turnOnFlashLight and do:

In protected void createCameraPreview()

...
Surface surface = new Surface(texture);
captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);

// Add this line:
captureRequestBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH);

captureRequestBuilder.addTarget(surface);
...