viewpager+radiogroup实现fragment实现联动并进行懒加载

懒加载Fragment

最新推荐文章于 2024-01-27 10:49:46 发布

原创最新推荐文章于 2024-01-27 10:49:46 发布 · 300 阅读

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本文介绍了一个通用的BaseFragment类实现，通过双标记的方式实现Fragment的懒加载功能，确保只有当Fragment的视图创建完成且对用户可见时才会加载数据。同时展示了如何在MainActivity中使用ViewPager配合该Fragment实现页面切换。

1.BaseFragment

public abstract class BaseFragment extends Fragment {
    private View view;
    //Fragment的View加载完毕的标记
    private boolean isViewCreated;

    //Fragment对用户可见的标记
    private boolean isUIVisible;

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        isViewCreated=true;
        lazyLoad();
    }
    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);
        //isVisibleToUser这个boolean值表示:该Fragment的UI 用户是否可见
        if (isVisibleToUser) {
            isUIVisible = true;
            lazyLoad();
        } else {
            isUIVisible = false;
        }
    }
    private void lazyLoad() {
        //这里进行双重标记判断,是因为setUserVisibleHint会多次回调,并且会在onCreateView执行前回调,必须确保onCreateView加载完毕且页面可见,才加载数据
        if (isViewCreated && isUIVisible) {
            loadData();
            //数据加载完毕,恢复标记,防止重复加载
            isViewCreated = false;
            isUIVisible = false;

        }
    }

    private void loadData() {

    }

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        view = inflater.inflate(initlayout(), container, false);
        return view;
    }



    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        initview(view);
        initData();
    }
    protected abstract int initlayout();
    protected abstract void initview(View view);
    protected abstract void initData();
}

2.MainActivity

public class MainActivity extends FragmentActivity {

    @BindView(R.id.viewpager)
    ViewPager viewpager;
    @BindView(R.id.btn1)
    RadioButton btn1;
    @BindView(R.id.btn2)
    RadioButton btn2;
    @BindView(R.id.btn3)
    RadioButton btn3;
    @BindView(R.id.btn4)
    RadioButton btn4;
    @BindView(R.id.btn5)
    RadioButton btn5;
    @BindView(R.id.group)
    RadioGroup group;
    private ArrayList<Fragment> list;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
        //创建Fragment集合
        list = new ArrayList<>();
        //将5个fragment加入集合中
        list.add(new FragmentOne());
        list.add(new FragmentTwo());
        list.add(new FragmentThree());
        list.add(new FragmentFour());
        list.add(new FragmentFive());
        //创建viewpager适配器
        viewpager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int i) {
                return list.get(i);
            }

            @Override
            public int getCount() {
                return list.size();
            }
        });
        //设置按钮点击事件
        group.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                switch (checkedId){
                    case R.id.btn1:
                        viewpager.setCurrentItem(0);
                        break;
                    case R.id.btn2:
                        viewpager.setCurrentItem(1);
                        break;
                    case R.id.btn3:
                        viewpager.setCurrentItem(2);
                        break;
                    case R.id.btn4:
                        viewpager.setCurrentItem(3);
                        break;
                    case R.id.btn5:
                        viewpager.setCurrentItem(4);
                        break;
                        default:
                            break;
                }
            }
        });
        //viewpager滑动事件
        viewpager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int i, float v, int i1) {

            }

            @Override
            public void onPageSelected(int i) {
                switch (i){
                    case 0:
                        group.check(R.id.btn1);
                        break;
                    case 1:
                        group.check(R.id.btn2);
                        break;
                    case 2:
                        group.check(R.id.btn3);
                        break;
                    case 3:
                        group.check(R.id.btn4);
                        break;
                    case 4:
                        group.check(R.id.btn5);
                        break;
                        default:
                            break;
                }
            }

            @Override
            public void onPageScrollStateChanged(int i) {

            }
        });





    }
}