Fragment懒加载

1.懒加载Fragment:
 1 public abstract class LazyFragment extends Fragment {
 2     boolean isViewPrepared; // 标识fragment视图已经初始化完毕
 3     boolean hasFetchData; // 标识已经触发过懒加载数据
 4 
 5 
 6     @Override
 7     public void setUserVisibleHint(boolean isVisibleToUser) {
 8         super.setUserVisibleHint(isVisibleToUser);
 9         if (isVisibleToUser) {//当当前为显示页面时
10             lazyFetchDataIfPrepared();
11         }
12     }
13 
14     @Override
15     public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
16         super.onViewCreated(view, savedInstanceState);
17         isViewPrepared = true;
18     }
19 
20     @Override
21     public void onActivityCreated(@Nullable Bundle savedInstanceState) {
22         super.onActivityCreated(savedInstanceState);
23         lazyFetchDataIfPrepared();
24     }
25 
26     void lazyFetchDataIfPrepared() {
27         // 用户可见fragment && 没有加载过数据 && 视图已经准备完毕
28         if (getUserVisibleHint() && !hasFetchData && isViewPrepared) {
29             hasFetchData = true; //已加载过数据
30             lazyFetchData();
31         }
32     }
33 
34     //获得数据操作
35     abstract void lazyFetchData();
36 }