Android Fragment 监听hide和show

源码给你 自己体会

/***
 * util
 * 1.fragment add and monitor showing and hiding
 */

private Fragment mFragment;
private FragmentSubscriber subscriber;

protected void addFragment(int frameLayoutId, Fragment fragment) {
    if (subscriber == null) {
        subscriber = new FragmentSubscriber();
        getSupportFragmentManager().registerFragmentLifecycleCallbacks(subscriber, false);
    }

    if (fragment != null) {
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
        if (fragment.isAdded()) {
            if (mFragment != null) {
                mFragment.setUserVisibleHint(false);
                fragment.setUserVisibleHint(true);
                transaction.hide(mFragment).show(fragment);
            } else {
                fragment.setUserVisibleHint(true);
                transaction.show(fragment);
            }
        } else {
            if (mFragment != null) {
                mFragment.setUserVisibleHint(false);
                transaction.hide(mFragment).add(frameLayoutId, fragment);
            } else {
                transaction.add(frameLayoutId, fragment);
            }
        }
        mFragment = fragment;
        transaction.commit();
    }
}

static class FragmentSubscriber extends android.support.v4.app.FragmentManager.FragmentLifecycleCallbacks {
    @Override
    public void onFragmentViewCreated(android.support.v4.app.FragmentManager fm, Fragment f, View v, Bundle savedInstanceState) {
        super.onFragmentViewCreated(fm, f, v, savedInstanceState);
        f.setUserVisibleHint(true);
        //这样是合理的 因为不可能一add就hide
        //这样做是需要的 因为onCreate show是准确的一个Fragment visible的时机
    }
}

Fragment中重写

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    //do sth
}