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如何在 Camera2 API 上启用前置摄像头。有人可以帮忙吗？我有这个 Camera2 API 代码。这仅设置设备的主摄像头，我想在单击按钮时启用前后摄像头。什么是LENS_FACING_FRONT，我是 android 编程的新手。

 private void setUpCameraOutputs(int width, int height) {
    Activity activity = getActivity();
    CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
    try {
        for (String cameraId : manager.getCameraIdList()) {
            CameraCharacteristics characteristics
                    = manager.getCameraCharacteristics(cameraId);

            // We don't use a front facing camera in this sample.
            Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
            if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
                continue;
            }

            StreamConfigurationMap map = characteristics.get(
                    CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
            if (map == null) {
                continue;
            }

            // For still image captures, we use the largest available size.
            Size largest = Collections.max(
                    Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
                    new CompareSizesByArea());
            mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
                    ImageFormat.JPEG, /*maxImages*/2);
            mImageReader.setOnImageAvailableListener(
                    mOnImageAvailableListener, mBackgroundHandler);

            // Danger, W.R.! Attempting to use too large a preview size could  exceed the camera
            // bus' bandwidth limitation, resulting in gorgeous previews but the storage of
            // garbage capture data.
            mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
                    width, height, largest);

            // We fit the aspect ratio of TextureView to the size of preview we picked.
            int orientation = getResources().getConfiguration().orientation;
            if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
                mTextureView.setAspectRatio(
                        mPreviewSize.getWidth(), mPreviewSize.getHeight());
            } else {
                mTextureView.setAspectRatio(
                        mPreviewSize.getHeight(), mPreviewSize.getWidth());
            }

            mCameraId = cameraId;
            return;
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
    } catch (NullPointerException e) {
        // Currently an NPE is thrown when the Camera2API is used but not supported on the
        // device this code runs.
        ErrorDialog.newInstance(getString(R.string.camera_error))
                .show(getChildFragmentManager(), FRAGMENT_DIALOG);
    }
}
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1 回答 1

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我们可以使用它CameraManager来迭代系统中所有可用的相机，每个相机都有一个指定的 cameraId。使用cameraId，我们可以获取指定摄像头设备的属性。这些属性由类 CameraCharacteristics 表示。诸如“是前置摄像头还是后置摄像头”，“支持的输出分辨率”之类的东西可以在那里查询。

您可以在此处获取官方示例应用程序

这个在 Google Git repo 中找到的示例将演示在新 Marshmallow 中启动相机之前检查权限Camera2 API

看看这篇文章了解更多。

于 2015-11-18T12:03:44.007 回答