java - 尝试检测 ActionMode 内存泄漏

Question

几天来我一直在尝试寻找 ActionMode 内存泄漏的根源，但没有成功。我有一个包含多个 fragment 的 Activity ，当我离开具有 ActionMode 的 fragment (同时自动取消它)时，LeakCanary 检测到内存泄漏。

我已经在 destroy() 上取消了 ActionMode 和 ActionMode.Callback，甚至尝试在 onDestroyActionMode() 上这样做。

这是我的 LeakCanary 屏幕截图:

https://i.imgur.com/RUbdqj3.png

我希望有人能给我指出正确的方向。

附言我怀疑它与 ActionMode.Callback 有关。虽然，我找不到任何破坏它的 CallBack 方法。我使用 startSupportActionMode(mActionModeCallback) 启动 ActionMode。我也试图找到一种方法来从中删除 mActionModeCallback，但没有方法。

这是我完整的 ActionMode 代码:

private ActionMode mActionMode;
private ActionMode.Callback mActionModeCallback;

public void startCAB()
{
    if (mActionMode == null)
        mActionMode = ((AppCompatActivity) getActivity()).startSupportActionMode(mActionModeCallback);
}


private void buildActionModeCallBack()
{
    mActionModeCallback = new ActionMode.Callback() {
        @Override
        public boolean onCreateActionMode(ActionMode mode, Menu menu) {
            MenuInflater inflater = mode.getMenuInflater();
            inflater.inflate(R.menu.menu_cab, menu);
            return true;
        }

        @Override
        public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
            return false;
        }

        @Override
        public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
            switch (item.getItemId()) {
                ... Some Code ...
            }
        }

        @Override
        public void onDestroyActionMode(ActionMode mode) {
            mActionMode = null;
    mActionModeCallback = null; // Tried with and without this.
        }
    };
}

public void finishActionMode()
{
    mActionMode.finish();
}

@Override
public void onDestroy()
{
    super.onDestroy();
    mActionMode = null;
    mActionModeCallback = null;
}

包含 fragment 的父 Activity :

@Override
public void onTabUnselected(TabLayout.Tab tab)
{
    clearCAB();
}

private void clearCAB()
{
    int index = mPagerAdapter.getCurrentFragmentIndex();
    FragmentOne fragmentOne = (FragmentOne) mPagerAdapter.instantiateItem(mViewPager, index);
    fragmentOne.finishActionMode();
}

Answer 1

根据我的经验，如果你的ActionMode.Callback对象使用了匿名内部类，它可能会导致你的 fragment 内存泄漏。

也许你可以创建一个新类并实现 ActionMode.Callback 然后用它来放入 startSupportActionMode() 参数:

public class YourFragment extends skip implements skip, ActionMode.Callback {

    private ActionMode mActionMode;

    public void startCAB()
    {
        if (mActionMode == null)
            mActionMode = ((AppCompatActivity) getActivity()).startSupportActionMode(new SafeActionModeCallback(this));
    }

    public void finishActionMode()
    {
        mActionMode.finish();
    }

    @Override
    public boolean onCreateActionMode(ActionMode mode, Menu menu) {
        MenuInflater inflater = mode.getMenuInflater();
        inflater.inflate(R.menu.menu_cab, menu);
        return true;
    }

    @Override
    public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
        return false;
    }

    @Override
    public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
        switch (item.getItemId()) {
            // ... Some Code ...
        }
    }

    @Override
    public void onDestroyActionMode(ActionMode mode) {
        mActionMode = null;
    }
}

安全操作模式回调:

public class SafeActionModeCallback implements ActionMode.Callback {

    // you can also use the WeakReference
    private ActionMode.Callback callback;

    public SafeActionModeCallback(ActionMode.Callback callback) {
        this.callback = callback;
    }

    @Override
    public boolean onCreateActionMode(ActionMode mode, Menu menu) {
        return callback.onCreateActionMode(mode, menu);
    }

    @Override
    public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
        return callback.onPrepareActionMode(mode, menu);
    }

    @Override
    public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
        return callback.onActionItemClicked(mode, item);
    }

    @Override
    public void onDestroyActionMode(ActionMode mode) {
        callback.onDestroyActionMode(mode);
        callback = null;
    }
}