关于fragmentPagerAdapter的冲突问题

最新推荐文章于 2022-02-17 21:55:19 发布

木齐亚

最新推荐文章于 2022-02-17 21:55:19 发布

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本文链接：https://blog.youkuaiyun.com/ghdmao/article/details/51689788

本文介绍了解决FragmentPagerAdapter在不同包间冲突的方法。一种方法是替换所有Fragment为V4包下的实现，另一种方法是自定义一个适配器类，将V4包替换为app包，以确保兼容性。

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  fragmentPagerAdapter是继承了PagerAdapter，这个类的作用就是用于滑动跳转Fragment，但是这个类是V4包里独有的，

android app包里并没有这个类，那么问题就来了，当自己前面用的Fragment以及fragmentmanager都是app包下的，两者无法兼容，那该怎么办？

  本人找了两种办法解决这个方案：第一种便是将所有的fragment全部换成V4包下的，但是这样也会有许多不兼容的因素出现。

  第二种就是打开fragmentPagerAdapter这个类的源码，然后自己新建一个类，将它copy到这个类里，然后将里面所有V4的包全部改成app的，代码如下：


public class MyPageAdapter extends PagerAdapter {

    private final FragmentManager mFragmentManager;
    private FragmentTransaction mCurTransaction = null;
    private Fragment mCurrentPrimaryItem = null;
    private List<Fragment> fragmentList;

    public MyPageAdapter(FragmentManager fm, List<Fragment> fragmentList) {
        mFragmentManager = fm;
        this.fragmentList = fragmentList;
    }

    public Fragment getItem(int position) {

        return fragmentList.get(position);
    }

    @Override
    public int getCount() {
        return fragmentList.size();
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }

        final long itemId = getItemId(position);

        // Do we already have this fragment?
        String name = makeFragmentName(container.getId(), itemId);
        Fragment fragment = mFragmentManager.findFragmentByTag(name);
        if (fragment != null) {
            mCurTransaction.attach(fragment);
        } else {
            fragment = getItem(position);
            mCurTransaction.add(container.getId(), fragment,
                    makeFragmentName(container.getId(), itemId));
        }
        if (fragment != mCurrentPrimaryItem) {
            fragment.setMenuVisibility(false);
            fragment.setUserVisibleHint(false);
        }

        return fragment;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        if (mCurTransaction == null) {
            mCurTransaction = mFragmentManager.beginTransaction();
        }
        mCurTransaction.detach((Fragment)object);
    }

    @Override
    public void setPrimaryItem(ViewGroup container, int position, Object object) {
        Fragment fragment = (Fragment)object;
        if (fragment != mCurrentPrimaryItem) {
            if (mCurrentPrimaryItem != null) {
                mCurrentPrimaryItem.setMenuVisibility(false);
                mCurrentPrimaryItem.setUserVisibleHint(false);
            }
            if (fragment != null) {
                fragment.setMenuVisibility(true);
                fragment.setUserVisibleHint(true);
            }
            mCurrentPrimaryItem = fragment;
        }
    }

    @Override
    public void finishUpdate(ViewGroup container) {
        if (mCurTransaction != null) {
            mCurTransaction.commitAllowingStateLoss();
            mCurTransaction = null;
            mFragmentManager.executePendingTransactions();
        }
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return ((Fragment)object).getView() == view;
    }

    @Override
    public Parcelable saveState() {
        return null;
    }

    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {
    }

    /**
     * Return a unique identifier for the item at the given position.
     *
     * <p>The default implementation returns the given position.
     * Subclasses should override this method if the positions of items can change.</p>
     *
     * @param position Position within this adapter
     * @return Unique identifier for the item at position
     */
    public long getItemId(int position) {
        return position;
    }

    private static String makeFragmentName(int viewId, long id) {
        return "android:switcher:" + viewId + ":" + id;
    }
}
如此便解决了fragmentPagerAdapter冲突的问题。