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| public abstract class BaseLazyFragment extends Fragment {
protected View mRootView; protected Context mContext; protected boolean isVisible; private boolean isPrepared; private boolean isFirst = true;
@Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); isPrepared = true; initPrepare(); }
@Override public void setUserVisibleHint(boolean isVisibleToUser) { super.setUserVisibleHint(isVisibleToUser); if (getUserVisibleHint()) { isVisible = true; lazyLoad(); } else { isVisible = false; onInvisible(); } }
@Override public void onResume() { super.onResume(); if (getUserVisibleHint()) { setUserVisibleHint(true); } }
@Override public void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); mContext = getActivity(); }
@Nullable @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { if (mRootView == null) { mRootView = initView(inflater, container, savedInstanceState); }
return mRootView; }
protected void lazyLoad() { if (!isPrepared || !isVisible || !isFirst) { return; } initData(); isFirst = false; }
protected abstract void initPrepare();
protected abstract void onInvisible();
protected abstract void initData();
protected abstract View initView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState);
}
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| import android.os.Bundle; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup;
import java.util.List;
public abstract class LazyLoadBaseFragment extends BaseLifeCircleFragment {
protected View rootView = null;
private boolean mIsFirstVisible = true;
private boolean isViewCreated = false;
private boolean currentVisibleState = false;
@Override public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { super.onCreateView(inflater, container, savedInstanceState);
if (rootView == null) { rootView = inflater.inflate(getLayoutRes(), container, false); } initView(rootView); return rootView; }
@Override public void setUserVisibleHint(boolean isVisibleToUser) { super.setUserVisibleHint(isVisibleToUser); if (isViewCreated) { if (isVisibleToUser && !currentVisibleState) { dispatchUserVisibleHint(true); } else if (!isVisibleToUser && currentVisibleState) { dispatchUserVisibleHint(false); } } }
@Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState);
isViewCreated = true; if (!isHidden() && getUserVisibleHint()) { dispatchUserVisibleHint(true); }
}
@Override public void onHiddenChanged(boolean hidden) { super.onHiddenChanged(hidden); LogUtils.e(getClass().getSimpleName() + " onHiddenChanged dispatchChildVisibleState hidden " + hidden);
if (hidden) { dispatchUserVisibleHint(false); } else { dispatchUserVisibleHint(true); } }
@Override public void onResume() { super.onResume(); if (!mIsFirstVisible) { if (!isHidden() && !currentVisibleState && getUserVisibleHint()) { dispatchUserVisibleHint(true); } } }
@Override public void onPause() { super.onPause(); if (currentVisibleState && getUserVisibleHint()) { dispatchUserVisibleHint(false); } }
private void dispatchUserVisibleHint(boolean visible) { if (visible && isParentInvisible()) return;
if (currentVisibleState == visible) { return; }
currentVisibleState = visible;
if (visible) { if (mIsFirstVisible) { mIsFirstVisible = false; onFragmentFirstVisible(); } onFragmentResume(); dispatchChildVisibleState(true); } else { dispatchChildVisibleState(false); onFragmentPause(); } }
private boolean isParentInvisible() { Fragment parentFragment = getParentFragment(); if (parentFragment instanceof LazyLoadBaseFragment ) { LazyLoadBaseFragment fragment = (LazyLoadBaseFragment) parentFragment; return !fragment.isSupportVisible(); }else { return false; } }
private boolean isSupportVisible() { return currentVisibleState; }
private void dispatchChildVisibleState(boolean visible) { FragmentManager childFragmentManager = getChildFragmentManager(); List<Fragment> fragments = childFragmentManager.getFragments(); if (!fragments.isEmpty()) { for (Fragment child : fragments) { if (child instanceof LazyLoadBaseFragment && !child.isHidden() && child.getUserVisibleHint()) { ((LazyLoadBaseFragment) child).dispatchUserVisibleHint(visible); } } } }
public void onFragmentFirstVisible() { LogUtils.e(getClass().getSimpleName() + " 对用户第一次可见");
}
public void onFragmentResume() { LogUtils.e(getClass().getSimpleName() + " 对用户可见"); }
public void onFragmentPause() { LogUtils.e(getClass().getSimpleName() + " 对用户不可见"); }
@Override public void onDestroyView() { super.onDestroyView(); isViewCreated = false; mIsFirstVisible = true; }
protected abstract int getLayoutRes();
protected abstract void initView(View rootView); }
|
对于可见状态的生命周期调用顺序,父 Fragment总是优先于子 Fragment,而对于不可见事件,内部的 Fragment 生命周期总是先于外层 Fragment。