Android- viewPager +fragment 实现懒加载 

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
public abstract class LazyLoadFragment extends BaseLazyFragment {
    protected boolean isViewInitiated;
    protected boolean isVisibleToUser;
    protected boolean isDataInitiated;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Bundle bundle = getArguments();
        if (bundle != null && bundle.size() > 0) {
            initVariables(bundle);
        }
    }

    protected abstract void initVariables(Bundle bundle);

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        isViewInitiated = true;
        prepareFetchData();
    }

    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        this.isVisibleToUser = isVisibleToUser;
        prepareFetchData();
        if (getUserVisibleHint()) {
            onVisible();
        } else {
            onInvisible();
        }
    }

    protected abstract void onVisible();
    protected abstract void onInvisible();
    protected abstract void onFirstVisible();

    @Override
    public void onHiddenChanged(boolean hidden) {
        super.onHiddenChanged(hidden);
        this.isVisibleToUser = !hidden;
        prepareFetchData();
        if (!hidden) {
            onVisible();
        } else {
            onInvisible();
        }
    }

    public abstract void fetchData();

    public boolean prepareFetchData() {
        return prepareFetchData(false);
    }

    public boolean prepareFetchData(boolean forceUpdate) {
        if (isVisibleToUser && isViewInitiated && (!isDataInitiated || forceUpdate)) {
            fetchData();
            isDataInitiated = true;
            onFirstVisible();
            return true;
        }
        return false;
    }
}