如何在android中同时打开手电筒和前置摄像头

Question

在我的应用程序中的一个需求中，我需要弹出一个包含前置摄像头预览的活动，同时我需要打开手电筒为well.However我观察，我能打开手电筒和相机背面上，但没有前置摄像头和闪光灯together.Following是我的代码：

public class Cam extends Activity { 

     private static int cameraId = 0; 
     private Camera camera; 

     //Adding for camera preview 
     public static FrameLayout preview; 
     public static CameraPreview mPreview; 
     Context context; 

     ImageButton btnSwitch; 
     private boolean isFlashOn; 
     private boolean hasFlash; 
     Parameters params; 


     @Override 
     protected void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 

      Log.e("Cam","Inside onCreate"); 
      setContentView(R.layout.cam); 
      context = getApplicationContext();  

      btnSwitch = (ImageButton) findViewById(R.id.btnSwitch); 

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

      startCamera(); 

      // displaying button image 
      toggleButtonImage();   

      btnSwitch.setOnClickListener(new View.OnClickListener() { 

       @Override 
       public void onClick(View v) { 
        if (isFlashOn) { 
         turnOffFlash(); 
        } else { 
         turnOnFlash(); 
        } 
       } 
      });  
     } 

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

      turnOffFlash(); 

      Log.e("Cam","Inside onPause"); 
      try { 
       if (camera != null) { 
        camera.release(); 
        camera = null; 
        preview.removeView(mPreview); 
       } 

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

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

      Log.e("Cam","Inside onResume"); 
      try { 
       if(camera ==null) { 
        Log.d("Cam","in resume,camera is null"); 
        try { 
         camera = android.hardware.Camera.open(cameraId); //opens front cam    
         // camera = Camera.open(); when I use this I can on/off the flashlight,since I am using the back camera. 
         mPreview = new CameraPreview(this, camera); 
         preview = (FrameLayout) findViewById(R.id.camera_preview); 
         preview.addView(mPreview); 
        } catch (Exception e) { 
         e.printStackTrace(); 
        } 
       } 
      } catch (Exception e) { 
       e.printStackTrace(); 
      } 
     } 

     @Override 
     protected void onDestroy() { 
      super.onDestroy(); 
      Log.e("Cam","Inside onDestroy"); 
      if (camera != null) { 
       try { 
        camera.release(); 
        camera = null; 
        preview.removeView(mPreview); 
       } catch (Exception e) { 
        e.printStackTrace(); 
       } 
      } 
     } 

     private void startCamera() { 

        Log.e("Cam","Inside doInBackground"); 
        String msg = ""; 
        // Do we have a camera? 
        try { 
         if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) { 

         } else { 
          cameraId = AppFunctions.findFrontFacingCamera();//A function that returns 0 for front camera 
          if (cameraId < 0) { 

          } else { 

           try { 
            camera = Camera.open(cameraId);//opens front cam 
            // camera = Camera.open(); when I use this I can on/off the flashlight,since I am calling the back camera. 
            params = camera.getParameters(); 
            Log.e("Cam","camera id" + cameraId); 
            Log.e("Cam","params" + params); 
           } catch (Exception e) { 
            e.printStackTrace(); 
           } 

           try { 
            mPreview = new CameraPreview(getApplicationContext(), camera); 
            preview = (FrameLayout) findViewById(R.id.camera_preview); 
            preview.addView(mPreview); 
           } catch (Exception e) { 
            e.printStackTrace(); 
           } 
          } 
         } 
        } catch (Exception e3) { 
         e3.printStackTrace(); 
        } 
     } 

     private void turnOnFlash() { 
      Log.v("Cam","Inside turnOnFlash"); 
      if (!isFlashOn) { 
       if (camera == null || params == null) { 
        Log.v("Cam","camera or param is null"); 
        return; 
       } 

       params.setFlashMode(Parameters.FLASH_MODE_TORCH); 
       camera.setParameters(params); 
       camera.startPreview(); 
       isFlashOn = true; 

       // changing button/switch image 
       toggleButtonImage(); 
      } 

     } 

     /* 
     * Turning Off flash 
     */ 
     private void turnOffFlash() { 
      Log.v("Cam","Inside turnOffFlash"); 
      if (isFlashOn) { 
       if (camera == null || params == null) { 
        Log.v("Cam","camera or param is null"); 
        return; 
       } 
       params.setFlashMode(Parameters.FLASH_MODE_OFF); 
       camera.setParameters(params); 
       camera.stopPreview(); 
       isFlashOn = false; 

       // changing button/switch image 
       toggleButtonImage(); 
      } 
     } 

     private void toggleButtonImage(){ 
      if(isFlashOn){ 
       btnSwitch.setImageResource(R.drawable.btn_switch_on); 
      }else{ 
       btnSwitch.setImageResource(R.drawable.btn_switch_off); 
      } 
     } 
    } 

清单

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

哪有我打开手电筒和前门同时？任何帮助，将不胜感激 ！

Answer 1

手电筒

public void onToggleClicked(View view) { 
    PackageManager pm = context.getPackageManager(); 
    final Parameters p = camera.getParameters(); 
    if (isFlashSupported(pm)) { 
     boolean on = ((ToggleButton) view).isChecked(); 
     if (on) { 
      Log.i("info", "torch is turn on!"); 
      p.setFlashMode(Parameters.FLASH_MODE_TORCH); 
      camera.setParameters(p); 
      camera.startPreview(); 
     } else { 
      Log.i("info", "torch is turn off!"); 
      p.setFlashMode(Parameters.FLASH_MODE_OFF); 
      camera.setParameters(p); 
      camera.stopPreview(); 
     } 

摄像头：

ImageButton ib = (ImageButton) findViewById(R.id.buttonToast); 
    ib.setOnClickListener(new OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      Intent i = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); 
      startActivityForResult(i, CAPTURE_IMAGE_CAPTURE_CODE); 
     } 
    }); 

Answer 2

尝试打开手电筒在后台打开您的前置摄像头。 实际上，您可以在后台打开前置摄像头和手电筒。

这里如何在背景打开手电筒：this

这里如何在背景打开相机：this

Answer 3

以下代码检查了前置摄像头的情况下：

private Camera openFrontFacingCameraGingerbread() { 
    int cameraCount = 0; 
    Camera cam = null; 
    Camera.CameraInfo cameraInfo = new Camera.CameraInfo(); 
    cameraCount = Camera.getNumberOfCameras(); 
    for (int camIdx = 0; camIdx < cameraCount; camIdx++) { 
     Camera.getCameraInfo(camIdx, cameraInfo); 
     if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) { 
      try { 
       cam = Camera.open(camIdx); 
      } catch (RuntimeException e) { 
       Log.e(TAG, "Camera failed to open: " + e.getLocalizedMessage()); 
      } 
     } 
    } 

    return cam; 
} 

然后在AndroidManifest.xml文件中添加以下权限：

<uses-permission android:name="android.permission.CAMERA" /> 
<uses-feature android:name="android.hardware.camera" android:required="false" /> 
<uses-feature android:name="android.hardware.camera.front" android:required="false" /> 

注意：此功能在姜饼（2.3）和Android版本中可用。

我推荐使用类似于this示例中的surfaceView来实现工作手电筒。

希望这有助于:)