最近在开发相机的过程中遇到这样一个问题，相机打开闪光灯后拍照后照片特别的暗，刚开始打算修改一些拍照时的参数，提高曝光率啊，延长曝光时长来改善照片问题

如一下思路

1.通过设置曝光时间范围(CaptureRequest.CONTROL_AE_TARGET_FPS_RANGE)，增加感光元件的曝光时间，接收到更多的光线，使得弱光场景下拍的更亮。

/设置预览请求的方式 previewBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);   ...   //自动对焦 previewBuilder.set(CaptureRequest.CONTROL_AF_MODE,CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE); //设置自动曝光帧率范围 previewBuilder.set(CaptureRequest.CONTROL_AE_TARGET_FPS_RANGE,getRange());  //对焦触发器设置为空闲状态 previewBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,CaptureRequest.CONTROL_AF_TRIGGER_IDLE); captureSession.setRepeatingRequest(previewBuilder.build(),captureCallback, mainHandler);    private Range getRange() {         CameraManager mCameraManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);         CameraCharacteristics chars = null;         try {             chars = mCameraManager.getCameraCharacteristics(cameraID);         } catch (CameraAccessException e) {             e.printStackTrace();         }         Range[] ranges = chars.get(CameraCharacteristics.CONTROL_AE_AVAILABLE_TARGET_FPS_RANGES);           Range result = null;           for (Range range : ranges) {             //帧率不能太低，大于10             if (range.getLower()