爲什麼我的應用在使用android.hardware.Camera.Open（）時崩潰？

Question

我正在爲大多數Android版本重新編寫應用程序。該應用程序設置爲在啓動時致電android.hardware.Camera.Open()。當應用程序啓動它給出了錯誤Camera Error: Could not connect to camera

在AndroidManifest.xml的權限是

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

爲什麼不能將它連接到相機？

Answer 1

問題解決了！

這個問題只是一個大寫的問題。該行<uses-permission android:name="android.permission.camera"/>實際上應該讀取<uses-permission android:name="android.permission.CAMERA"/>。發生這種情況是因爲camera是硬件功能，而CAMERA是一個權限。

Answer 2

不僅宣佈在manifest但你也需要在運行時從用戶授予permission爲Android 6.+ 使用下面的代碼段用於以使用相機硬件授予camera permission

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) { 
          if (ContextCompat.checkSelfPermission(SplashScreenActivty.this, Manifest.permission.CAMERA) 
            != PackageManager.PERMISSION_GRANTED) { 
           ActivityCompat.requestPermissions(this, 
             new String[]{Manifest.permission.CAMERA}, 
             1); 
          } 

         } 


@Override 
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) { 
     super.onRequestPermissionsResult(requestCode, permissions, grantResults); 

     switch (requestCode) { 
      case 1: { 

       // If request is cancelled, the result arrays are empty. 
       if (grantResults.length > 0 
         && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 


        // permission was granted, yay! Do the 
        // camera-related task you need to do. 
       } else { 

        // permission denied, boo! Disable the 
        // functionality that depends on this permission. 

        Toast.makeText(this, "Permission denied to read SMS", Toast.LENGTH_SHORT).show(); 
        finish(); 
       } 
      } 

      // other 'case' lines to check for other 
      // permissions this app might request 
     } 
    } 

Answer 3

在舊版Android設備足夠說明適當的權限並在Android清單中使用，但自從Marshmallow版本出現後，再不能運行該應用程序。因爲還需要啓用運行時權限。考慮使用類似的代碼，並將其應用於您的項目，因爲它使您有機會檢查並啓用權限。

@Override 
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { 
    if (requestCode == PERMISSION_REQUEST_CODE) { 
     if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { 

      cameraPreview.initializeCamera(); 
     } else { 

     } 
     return; 
    } 
    super.onRequestPermissionsResult(requestCode, permissions, grantResults); 
} 


@Override 
protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
    if (requestCode == PERMISSION_REQUEST_CODE) { 
     cameraPreview.initializeCamera(); 
     return; 
    } 
    super.onActivityResult(requestCode, resultCode, data); 
} 


    public void requestCameraPermission() { 
    ActivityCompat.requestPermissions(this, 
      new String[]{ 
        Manifest.permission.CAMERA 
      }, 
      PERMISSION_REQUEST_CODE); 
} 

public void requestPermissionWithRationale() { 
    if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA)) { 
     Snackbar.make(findViewById(android.R.id.content), R.string.no_cam_permission, Snackbar.LENGTH_INDEFINITE) 
       .setAction(R.string.snackbar_action_grant, new View.OnClickListener() { 
        @Override 
        public void onClick(View v) { 
         requestCameraPermission(); 
        } 
       }) 
       .show(); 
    } else { 
     requestCameraPermission(); 
    } 
} 

Answer 4

使用相機爲已過時

下面是代碼

UPDATE --->

@Module 
public class CameraModule { 

    @Provides 
    CameraSupport provideCameraSupport() { 
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { 
      return new CameraNew(context); 
     } else { 
      return new CameraOld(); 
     } 
    } 
} 

，然後舊目標：

@SuppressWarnings("deprecation") 
public class CameraOld implements CameraSupport { 

    private Camera camera; 

    @Override 
    public CameraSupport open(final int cameraId) { 
     this.camera = Camera.open(cameraId); 
     return this; 
    } 

    @Override 
    public int getOrientation(final int cameraId) { 
     Camera.CameraInfo info = new Camera.CameraInfo(); 
     Camera.getCameraInfo(cameraId, info); 
     return info.orientation; 
    } 
} 

新目標：

public class CameraNew implements CameraSupport { 

    private CameraDevice camera; 
    private CameraManager manager; 

    public CameraNew(final Context context) { 
     this.manager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE); 
    } 

    @TargetApi(Build.VERSION_CODES.LOLLIPOP) 
    @Override 
    public CameraSupport open(final int cameraId) { 
     try { 
      String[] cameraIds = manager.getCameraIdList(); 
      if (ActivityCompat.checkSelfPermission(CameraPreview.this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { 
       // TODO: Consider calling 
       // ActivityCompat#requestPermissions 
       // here to request the missing permissions, and then overriding 
       // public void onRequestPermissionsResult(int requestCode, String[] permissions, 
       //           int[] grantResults) 
       // to handle the case where the user grants the permission. See the documentation 
       // for ActivityCompat#requestPermissions for more details. 

       return null; 
      } 
      manager.openCamera(cameraIds[cameraId], new CameraDevice.StateCallback() { 
       @Override 
       public void onOpened(CameraDevice camera) { 
        CameraNew.this.camera = camera; 
       } 

       @Override 
       public void onDisconnected(CameraDevice camera) { 
        CameraNew.this.camera = camera; 
        // TODO handle 
       } 

       @Override 
       public void onError(CameraDevice camera, int error) { 
        CameraNew.this.camera = camera; 
        // TODO handle 
       } 
      }, null); 
     } catch (Exception e) { 
      // TODO handle 
     } 
     return this; 
    } 

    @TargetApi(Build.VERSION_CODES.LOLLIPOP) 
    @Override 
    public int getOrientation(final int cameraId) { 
     try { 
      String[] cameraIds = manager.getCameraIdList(); 
      CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraIds[cameraId]); 
      return characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION); 
     } catch (CameraAccessException e) { 
      // TODO handle 
      return 0; 
     } 
    } 
}