Nexus5閃光燈問題？

Question

我想在android中打開Nexus5閃光燈，但我在logcat中發現錯誤。 可以打開它嗎？

我的代碼是在這裏：

活動的Java

public class MainActivity extends Activity { 
    Camera camera; 
    Parameters parameters; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     final Switch switch1 = (Switch) findViewById(R.id.switch1); 

     switch1.setOnCheckedChangeListener(new OnCheckedChangeListener() { 

      @Override 
      public void onCheckedChanged(CompoundButton arg0, boolean arg1) { 
       // TODO Auto-generated method stub 
       if (switch1.isChecked()) { 

        camera = Camera.open(); 
        parameters = camera.getParameters(); 
        parameters.setFlashMode(Parameters.FLASH_MODE_ON); 
        camera.setParameters(parameters); 
        Toast.makeText(getApplicationContext(), 
          "Turning on FlashLight..", Toast.LENGTH_LONG) 
          .show(); 

       } else { 

        parameters.setFlashMode(Parameters.FLASH_MODE_OFF); 
        camera.setParameters(parameters); 
        camera.release(); 
        camera = null; 
        Toast.makeText(getApplicationContext(), 
          "Turning off FlashLight..", Toast.LENGTH_LONG) 
          .show(); 

       } 
      } 
     }); 
    } 

} 

，我使用這些權限。

<uses-permission android:name="android.permission.CAMERA" /> 
    <uses-feature android:name="android.hardware.camera" /> 
    <uses-permission android:name="android.permission.FLASHLIGHT"/> 
    <uses-feature android:name="android.hardware.camera.flash" /> 
    <uses-feature android:name="android.hardware.camera.autofocus" /> 

    05-07 10:08:26.970: W/CameraBase(19606): An error occurred while connecting to camera: 0 
    05-07 10:08:26.970: D/AndroidRuntime(19606): Shutting down VM 
    05-07 10:08:26.970: W/dalvikvm(19606): threadid=1: thread exiting with uncaught exception (group=0x41682ba8) 
    05-07 10:08:26.970: E/AndroidRuntime(19606): FATAL EXCEPTION: main 
    05-07 10:08:26.970: E/AndroidRuntime(19606): Process: com.systelligence.androidflashlight, PID: 19606 
    05-07 10:08:26.970: E/AndroidRuntime(19606): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.systelligence.androidflashlight/com.systelligence.androidflashlight.MainActivity}: java.lang.RuntimeException: Fail to connect to camera service 
    05-07 10:08:26.970: E/AndroidRuntime(19606): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) 
    05-07 10:08:26.970: E/AndroidRuntime(19606): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
    05-07 10:08:26.970: E/AndroidRuntime(19606): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3738) 
    05-07 10:08:26.970: E/AndroidRuntime(19606): at android.app.ActivityThread.access$900(ActivityThread.java:135) 
    05-07 10:08:26.970: E/AndroidRuntime(19606): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1202) 
    05-07 10:08:26.970: E/AndroidRuntime(19606): at android.os.Handler.dispatchMessage(Handler.java:102) 
    05-07 10:08:26.970: E/AndroidRuntime(19606): at android.os.Looper.loop(Looper.java:136) 

Answer 1

我會使用下面的代碼。在我的Nexus手機上完美工作。我需要實現SurfaceView來達到這個目的：

public class ConcertFragment extends Fragment implements SurfaceHolder.Callback { 

ToggleButton btnFlashlight; 
View rootView; 
private Camera cam; 
private boolean hasFlash; 
boolean hasCamera; 
boolean isFlashOn; 

@Override 
public void onStart() { 
    super.onStart(); 
    SurfaceView preview = (SurfaceView)getView().findViewById(R.id.background); 
    SurfaceHolder mHolder = preview.getHolder(); 
    mHolder.addCallback(this); 
} 

@Override 
public void onPause(){ 
    super.onPause(); 
    turnOffFlash(); 
} 

@Override 
public void onActivityCreated(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    getCamera(); 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 

    rootView = inflater.inflate(R.layout.fragment_concert, container, false); 

    hasFlash = getActivity().getApplicationContext().getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH); 

    if (!hasFlash) { 
     // device doesn't support flash 
     // Show alert message and close the application 
     AlertDialog alert = new AlertDialog.Builder(getActivity()).create(); 

     alert.setTitle("No Flash"); 
     alert.setMessage("Sorry, device is not flash supported."); 
     alert.setButton(DialogInterface.BUTTON_POSITIVE, "OK", new android.content.DialogInterface.OnClickListener() { 
      @Override 
      public void onClick(DialogInterface dialog, int which) { 

      } 
     }); 
     alert.show(); 
    } 
    btnFlashlight = (ToggleButton) rootView.findViewById(R.id.toggleButton); 
     btnFlashlight.setOnCheckedChangeListener(new OnCheckedChangeListener() { 

      @Override 
      public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { 
       if (isFlashOn) { 
        // turn off flash 
        turnOffFlash(); 
       } else { 
        // turn on flash 
        turnOnFlash(); 
       } 
      } 
     }); 
    return rootView; 
} 

private void turnOnFlash() { 
    if (!isFlashOn) { 
     if (cam == null || params == null) { 
      return; 
     } 

     params = cam.getParameters(); 
     params.setFlashMode(Parameters.FLASH_MODE_TORCH); 
     cam.setParameters(params); 
     cam.startPreview(); 
     isFlashOn = true; 
    } 
} 

private void turnOffFlash() { 
    if (isFlashOn) { 
     if (cam == null || params == null) { 
      return; 
     } 

     params = cam.getParameters(); 
     params.setFlashMode(Parameters.FLASH_MODE_OFF); 
     cam.setParameters(params); 
     cam.stopPreview(); 
     cam.release(); 
     isFlashOn = false; 
    } 
} 

// Get the camera 
    private void getCamera() { 
     if (cam != null) { 
      try { 
       cam = Camera.open(); 
       params = cam.getParameters(); 
       cam.startPreview(); 
       hasCamera = true; 

      } catch (RuntimeException e) { 
       Log.e("Camera Error. Failed to Open. Error: ", e.getMessage()); 
      } 
     } 
    } 

@Override 
public void surfaceChanged(SurfaceHolder holder,int format,int width,int height) { 

} 

@Override 
public void surfaceDestroyed(SurfaceHolder holder) { 
    if (cam != null) { 
     cam.stopPreview(); 
     cam.setPreviewCallback(null); 
     cam.release(); 
     cam = null; 
     btnFlashlight.setChecked(false); 
    } 
} 

@Override 
public void surfaceCreated(SurfaceHolder holder) { 
    if (cam == null) { 
     cam = Camera.open(); 
     params = cam.getParameters(); 
     try { 
      cam.setPreviewDisplay(holder); 
     } catch (IOException e) { 
      cam.release(); 
      cam = null; 
     } 
    } 
}