Android应用程序在暂停时崩溃

Question

我有一个android活动，它使用surfaceview显示实时相机预览。一切工作正常，但是当我按手机上的锁定按钮，然后解锁我的手机或从另一个活动（例如蓝牙传输或来电）的对话框覆盖我的相机预览应用程序崩溃。我怀疑这是我的onResume()或onPause()活动的问题，因为我收到一个错误“在release（）之后调用的方法”。但是，我不确定如何解决这个问题。

摄像头活动：

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_camera_screen); 
    setStatusBarColor(); 
    Display display = getWindowManager().getDefaultDisplay(); 
    final int height = display.getHeight(); 

    session = new SessionManager(getApplicationContext()); 
    try { 
     mCamera = Camera.open();//you can use open(int) to use different cameras 
    } catch (Exception e) { 
     Log.d("ERROR", "Failed to get camera: " + e.getMessage()); 
    } 


    if (mCamera != null) { 
     mCameraView = new CameraPreview(this, mCamera);//create a SurfaceView to show camera data 
     FrameLayout camera_view = (FrameLayout) findViewById(R.id.camera_view); 
     camera_view.addView(mCameraView);//add the SurfaceView to the layout 
     //rotate preview 
     mCamera.setDisplayOrientation(90); 
    //rotate camera 
     Camera.Parameters p = mCamera.getParameters(); 
     p.setRotation(90); 
     mCamera.setParameters(p); 
    } 
    @Override 
protected void onPause() { 
    super.onPause(); 
    if (mCamera != null) { 
     mCamera.setPreviewCallback(null); 
     mCameraView.getHolder().removeCallback(mCameraView); 
     mCamera.release(); 
    } 
} 
@Override 
public void onResume() { 
    super.onResume(); 

    // Get the Camera instance as the activity achieves full user focus 
    if (mCamera == null) { 
     initializeCamera(); // Local method to handle camera initialization 
    } 
} 



protected void initializeCamera(){ 
    // Get an instance of Camera Object 
    try{ 
     mCamera = Camera.open();//you can use open(int) to use different cameras 
    } catch (Exception e){ 
     Log.d("ERROR", "Failed to get camera: " + e.getMessage()); 
    } 


    if(mCamera != null) { 
     mCameraView = new CameraPreview(this, mCamera);//create a SurfaceView to show camera data 
     FrameLayout camera_view = (FrameLayout)findViewById(R.id.camera_view); 
     camera_view.addView(mCameraView);//add the SurfaceView to the layout 
    } 

}

Answer 1

尝试加入这一行到您的onPause（）：

camera_view.removeView(mCameraView); 

Answer 2

onPause(){ 
... 
mCamera.release(); // close mCamera, but not set it to null 
//mCamera = null; // you need reset mCamera to trigger init method; 
} 
onResume(){ 
... 
initializeCamera();// need mCamera == null 
} 

//If you find other problems. 
//Add some codes in the initializeCamera(). 
{ 
//mCamera.setPreviewCallback("something"); 
//mCameraView.getHolder().addCallback(mCameraView); 
} 
//as onPause do.