打开手电筒代码

参考文章：
关于Android 7.0 手电筒的控制

try {
    //获取CameraManager
    CameraManager mCameraManager = (CameraManager) MyApplication.getContext().getSystemService(Context.CAMERA_SERVICE);
    //获取当前手机所有摄像头设备ID
    String[] ids  = mCameraManager.getCameraIdList();
    for (String id : ids) {
        CameraCharacteristics c = mCameraManager.getCameraCharacteristics(id);
        //查询该摄像头组件是否包含闪光灯
        Boolean flashAvailable = c.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
        /*
        * 获取相机面对的方向
        * CameraCharacteristics.LENS_FACING_FRONT 前置摄像头
        * CameraCharacteristics.LENS_FACING_BACK 后只摄像头
        * CameraCharacteristics.LENS_FACING_EXTERNAL 外部的摄像头
        */
        Integer lensFacing = c.get(CameraCharacteristics.LENS_FACING);
        if (flashAvailable != null && flashAvailable
                && lensFacing != null && lensFacing == CameraCharacteristics.LENS_FACING_BACK) {
            //打开或关闭手电筒
            mCameraManager.setTorchMode(id, OPEN? true:false);
        }
    }

} catch (CameraAccessException e) {
    e.printStackTrace();
}