如何在Android活动结束后发布相机？

我正在开发一个需要扫描QR码并点击图片的应用程序,但有时会发生相机应用程序崩溃并且说 Android相机已经停止工作并且设备需要重新启动才能正常运行的情况.

我希望能够从我的活动本身释放相机,以避免它在以后的任何情况下崩溃.
需要帮助！

扫描代码：

@Override
 public void onCreate(Bundle savedInstanceStatE)
   {
  super.onCreate(savedInstanceStatE);


       try{
       Intent intent = new Intent("com.google.zxing.client.android.SCAN");
          intent.putExtra("SCAN_MODE","QR_CODE_MODE");
          startActivityForResult(intent,0);
       }
       catch(Exception E)
       {
         // ERROR
       }
    }

public void onActivityResult(int requestCode,int resultCode,Intent intent) 
   {
     if (requestCode == 0) 
      {
      if (resultCode == RESULT_OK)
     {
        String contents = intent.getStringExtra("SCAN_RESULT");
        showPass(contents);

     }
      else if (resultCode == RESULT_CANCELED) 
      {
          showFail();
      } 
      }
   }

点击图片的代码：

public void takephoto(View v)
{

     Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
     startActivityForResult(cameraIntent,CAMERA_requEST);
}

protected void onActivityResult(int requestCode,Intent data) 
{
    if (requestCode == CAMERA_requEST)
    {
              Bitmap photo = (Bitmap) data.getExtras().get("data");
               // some action.
    }
}

protected void onDestroy(){

if(camera!=null){
            camera.stopPreview();
            camera.setPreviewCallBACk(null);

            camera.release();
            camera = null;
        }


}

public void surfaceDestroyed(SurfaceHolder holder) {

        if(camera!=null){
            camera.stopPreview();
            camera.setPreviewCallBACk(null);

            camera.release();
            camera = null;
        }

    }