@Override
  protected void onResume() {
    super.onResume();

    // CameraManager必须在这里初始化,而不是在onCreate()中。
    // 这是必须的,因为当我们第一次进入时需要显示帮助页,我们并不想打开Camera,测量屏幕大小
    // 当扫描框的尺寸不正确时会出现bug
    cameraManager = new CameraManager(getApplication());

    viewfinderView = (ViewfinderView) findViewById(R.id.viewfinder_view);
    viewfinderView.setCameraManager(cameraManager);

    handler = null;

    SurfaceView surfaceView = (SurfaceView) findViewById(R.id.preview_view);
    SurfaceHolder surfaceHolder = surfaceView.getHolder();
    if (hasSurface) {
      // activity在paused时但不会stopped,因此surface仍旧存在;
      // surfaceCreated()不会调用,因此在这里初始化camera
      initCamera(surfaceHolder);
    } else {
      // 重置callback,等待surfaceCreated()来初始化camera
      surfaceHolder.addCallback(this);
    }

    beepManager.updatePrefs();
    inactivityTimer.onResume();

    source = IntentSource.NONE;
    decodeFormats = null;
    characterSet = null;
  }
  @Override
  protected void onResume() {
    super.onResume();

    // CameraManager must be initialized here, not in onCreate(). This is necessary because we don't
    // want to open the camera driver and measure the screen size if we're going to show the help on
    // first launch. That led to bugs where the scanning rectangle was the wrong size and partially
    // off screen.
    cameraManager = new CameraManager(getApplication());

    viewfinderView = (ViewfinderView) findViewById(fakeR.getId("id", "viewfinder_view"));
    viewfinderView.setCameraManager(cameraManager);

    resultView = findViewById(fakeR.getId("id", "result_view"));
    statusView = (TextView) findViewById(fakeR.getId("id", "status_view"));

    handler = null;
    lastResult = null;

    resetStatusView();

    SurfaceView surfaceView = (SurfaceView) findViewById(fakeR.getId("id", "preview_view"));
    SurfaceHolder surfaceHolder = surfaceView.getHolder();
    if (hasSurface) {
      // The activity was paused but not stopped, so the surface still exists. Therefore
      // surfaceCreated() won't be called, so init the camera here.
      initCamera(surfaceHolder);
    } else {
      // Install the callback and wait for surfaceCreated() to init the camera.
      surfaceHolder.addCallback(this);
      surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    beepManager.updatePrefs();

    inactivityTimer.onResume();

    Intent intent = getIntent();

    SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
    copyToClipboard =
        prefs.getBoolean(PreferencesActivity.KEY_COPY_TO_CLIPBOARD, true)
            && (intent == null || intent.getBooleanExtra(Intents.Scan.SAVE_HISTORY, true));

    // source = IntentSource.NONE;
    source = IntentSource.NATIVE_APP_INTENT;
    decodeFormats = null;
    characterSet = null;

    if (intent != null) {

      String action = intent.getAction();
      String dataString = intent.getDataString();

      if (Intents.Scan.ACTION.equals(action)) {

        // Scan the formats the intent requested, and return the result to the calling activity.
        source = IntentSource.NATIVE_APP_INTENT;
        decodeFormats = DecodeFormatManager.parseDecodeFormats(intent);

        if (intent.hasExtra(Intents.Scan.WIDTH) && intent.hasExtra(Intents.Scan.HEIGHT)) {
          int width = intent.getIntExtra(Intents.Scan.WIDTH, 0);
          int height = intent.getIntExtra(Intents.Scan.HEIGHT, 0);
          if (width > 0 && height > 0) {
            cameraManager.setManualFramingRect(width, height);
          }
        }

        String customPromptMessage = intent.getStringExtra(Intents.Scan.PROMPT_MESSAGE);
        if (customPromptMessage != null) {
          statusView.setText(customPromptMessage);
        }

      } else if (dataString != null
          && dataString.contains(PRODUCT_SEARCH_URL_PREFIX)
          && dataString.contains(PRODUCT_SEARCH_URL_SUFFIX)) {

        // Scan only products and send the result to mobile Product Search.
        source = IntentSource.PRODUCT_SEARCH_LINK;
        sourceUrl = dataString;
        decodeFormats = DecodeFormatManager.PRODUCT_FORMATS;

      } else if (isZXingURL(dataString)) {

        // Scan formats requested in query string (all formats if none specified).
        // If a return URL is specified, send the results there. Otherwise, handle it ourselves.
        source = IntentSource.ZXING_LINK;
        sourceUrl = dataString;
        Uri inputUri = Uri.parse(sourceUrl);
        returnUrlTemplate = inputUri.getQueryParameter(RETURN_URL_PARAM);
        returnRaw = inputUri.getQueryParameter(RAW_PARAM) != null;
        decodeFormats = DecodeFormatManager.parseDecodeFormats(inputUri);
      }

      characterSet = intent.getStringExtra(Intents.Scan.CHARACTER_SET);
    }
  }