攝像頭權(quán)限關(guān)閉后異常

描述：當(dāng)app攝像頭權(quán)限打開后，運(yùn)行中的app和單例中的數(shù)據(jù)正常；切換到設(shè)置頁面關(guān)閉攝像頭權(quán)限后；再切換到app發(fā)生的變化
結(jié)果： activity會(huì)重新繪制，activity歷史棧會(huì)保留，但是回退到歷史棧的activity會(huì)重新從onCreate(***)開始；且單例中的數(shù)據(jù)被重置，例如：int 數(shù)據(jù)被重置為0，對(duì)象被重置為null

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單例代碼

public class CountManager {private CountManager() {}

    public static CountManager getInstance() {return SingleHolder.instance;
    }

    private static class SingleHolder {private static final CountManager instance = new CountManager();
    }

    private int mCount = 0;

    public void addCount() {mCount++;
    }

    public int getCount() {return mCount;
    }
}

第一個(gè)activity

public class MainActivity extends AppCompatActivity {private static final String TAG = "MainActivity-1";

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        CountManager.getInstance().addCount(); //單例中數(shù)據(jù)增加
        findViewById(R.id.btn_second_click).setOnClickListener(new View.OnClickListener() {@Override
            public void onClick(View v) {startActivity(new Intent(MainActivity.this, SecondActivity.class));
            }
        });
        Log.d(TAG, "onCreate: ");
    }

    @Override
    protected void onResume() {super.onResume();
        Log.d(TAG, "onResume: " + CountManager.getInstance().getCount());
    }

    @Override
    protected void onPause() {super.onPause();
        Log.d(TAG, "onPause: ");
    }

    @Override
    protected void onDestroy() {super.onDestroy();
        Log.d(TAG, "onDestroy: ");
    }
}

第二個(gè)activity

public class SecondActivity extends AppCompatActivity {private static final String TAG = "MainActivity-Second";

    @Override
    protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        CountManager.getInstance().addCount();
         if (savedInstanceState == null) {getSupportFragmentManager().beginTransaction()
                    .replace(R.id.container, MainFragment.newInstance())
                    .commitNow();
        }
        Log.d(TAG, "onCreate: ");
    }

    @Override
    protected void onResume() {super.onResume();
        Log.d(TAG, "onResume: "+ CountManager.getInstance().getCount());
    }

    @Override
    protected void onPause() {super.onPause();
        Log.d(TAG, "onPause: ");
    }

    @Override
    protected void onStop() {super.onStop();
        Log.d(TAG, "onStop: ");
    }

    @Override
    protected void onDestroy() {super.onDestroy();
        Log.d(TAG, "onDestroy: ");
    }
}

備注：記得app增加攝像頭權(quán)限

運(yùn)行結(jié)果

1、啟動(dòng)app后，在MainActivity，點(diǎn)擊跳轉(zhuǎn)到SecondActivity

D  onCreate: 
15:28:09.177 com.xiaoma.testc                     D  onResume: 1

15:28:11.663 com.xiaoma.testc                     D  onPause: 
15:28:11.708 com.xiaoma.testc                     D  onCreate: 
15:28:11.751 com.xiaoma.testc                     D  onResume: 2

2、切換到桌面，攝像頭權(quán)限進(jìn)行關(guān)閉操作或者打開后再關(guān)閉

15:31:44.956 com.xiaoma.testc                     D  onPause: 
15:31:44.989 com.xiaoma.testc                     D  onStop: 
---------------------------- PROCESS ENDED (31143) for package com.xiaoma.testc ----------------------------

可以看到進(jìn)程關(guān)閉了的信息
3、再次點(diǎn)擊app，查看里面的數(shù)據(jù)，然后進(jìn)行回退歷史棧

---------------------------- PROCESS STARTED (32348) for package com.xiaoma.testc ----------------------------
15:32:57.135 com.xiaoma.testc                     D  onCreate: 
15:32:57.170 com.xiaoma.testc                     D  onResume: 1
15:33:13.688 com.xiaoma.testc                     D  onPause: 
//返回操作后
15:33:13.751 com.xiaoma.testc                     D  onCreate: 
15:33:13.755 com.xiaoma.testc                     D  onResume: 2
15:33:14.162 com.xiaoma.testc                     D  onStop: 
15:33:14.167 com.xiaoma.testc                     D  onDestroy:

可以看到重啟啟動(dòng)了進(jìn)程，且歷史棧存在

總結(jié)

對(duì)于開發(fā)SDK的，由于需要宿主傳遞接口回調(diào)，會(huì)導(dǎo)致回調(diào)為null，所以在頁面需要進(jìn)行回調(diào)判斷，進(jìn)行相關(guān)的業(yè)務(wù)處理。

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