import zxing.camera.open.OpenCameraInterface; //导入依赖的package包/类
/**
 * Opens the camera driver and initializes the hardware parameters.
 * 
 * @param holder
 *            The surface object which the camera will draw preview frames
 *            into.
 * @throws IOException
 *             Indicates the camera driver failed to open.
 */
public synchronized void openDriver(SurfaceHolder holder) throws IOException {
	Camera theCamera = camera;
	if (theCamera == null) {

		if (requestedCameraId >= 0) {
			theCamera = OpenCameraInterface.open(requestedCameraId);
		} else {
			theCamera = OpenCameraInterface.open();
		}

		if (theCamera == null) {
			throw new IOException();
		}
		camera = theCamera;
	}
	theCamera.setPreviewDisplay(holder);

	if (!initialized) {
		initialized = true;
		configManager.initFromCameraParameters(theCamera);
	}

	Camera.Parameters parameters = theCamera.getParameters();
	String parametersFlattened = parameters == null ? null : parameters.flatten(); // Save
																					// these,
																					// temporarily
	try {
		configManager.setDesiredCameraParameters(theCamera, false);
	} catch (RuntimeException re) {
		// Driver failed
		Log.w(TAG, "Camera rejected parameters. Setting only minimal safe-mode parameters");
		Log.i(TAG, "Resetting to saved camera params: " + parametersFlattened);
		// Reset:
		if (parametersFlattened != null) {
			parameters = theCamera.getParameters();
			parameters.unflatten(parametersFlattened);
			try {
				theCamera.setParameters(parameters);
				configManager.setDesiredCameraParameters(theCamera, true);
			} catch (RuntimeException re2) {
				// Well, darn. Give up
				Log.w(TAG, "Camera rejected even safe-mode parameters! No configuration");
			}
		}
	}

}