FragmentPagerAdapter类文件可动态修改Frag

public class BaseFragmentPagerAdapter extends FragmentPagerAdapter {
    
        private List<Fragment> mFragmentList;
        private FragmentManager mFragmentManager;
        /**下面两个值用来保存Fragment的位置信息，用以判断该位置是否需要更新*/
        private SparseArray<String> mFragmentPositionMap;
        private SparseArray<String> mFragmentPositionMapAfterUpdate;
    
        public BaseFragmentPagerAdapter(FragmentManager fm, List<Fragment> fragments) {
            super(fm);
            mFragmentList = fragments;
            mFragmentManager = fm;
            mFragmentList = fragments;
            mFragmentPositionMap = new SparseArray<>();
            mFragmentPositionMapAfterUpdate = new SparseArray<>();
            setFragmentPositionMap();
            setFragmentPositionMapForUpdate();
        }
    
    
        /**
         * 保存更新之前的位置信息，用<hashCode, position>的键值对结构来保存
         */
        private void setFragmentPositionMap() {
            mFragmentPositionMap.clear();
            for (int i = 0; i < mFragmentList.size(); i++) {
                mFragmentPositionMap.put(Long.valueOf(getItemId(i)).intValue(), String.valueOf(i));
            }
        }
    
        /**
         * 保存更新之后的位置信息，用<hashCode, position>的键值对结构来保存
         */
        private void setFragmentPositionMapForUpdate() {
            mFragmentPositionMapAfterUpdate.clear();
            for (int i = 0; i < mFragmentList.size(); i++) {
                mFragmentPositionMapAfterUpdate.put(Long.valueOf(getItemId(i)).intValue(),  String.valueOf(i));
            }
        }
    
       /**
        * 在此方法中找到需要更新的位置返回POSITION_NONE，否则返回POSITION_UNCHANGED即可
        */
        @Override
        public int getItemPosition(Object object) {
            int hashCode = object.hashCode();
            //查找object在更新后的列表中的位置
            String position = mFragmentPositionMapAfterUpdate.get(hashCode);
            //更新后的列表中不存在该object的位置了
            if (position == null) {
                return POSITION_NONE;
            } else {
                //如果更新后的列表中存在该object的位置, 查找该object之前的位置并判断位置是否发生了变化
                int size = mFragmentPositionMap.size();
                for (int i = 0; i < size ; i++) {
                    int key = mFragmentPositionMap.keyAt(i);
                    if (key == hashCode) {
                        String index = mFragmentPositionMap.get(key);
                        if (position.equals(index)) {
                            //位置没变依然返回POSITION_UNCHANGED
                            return POSITION_UNCHANGED;
                        } else {
                            //位置变了
                            return POSITION_NONE;
                        }
                    }
                }
            }
            return POSITION_UNCHANGED;
        }
    
        /**
         * 将指定的Fragment替换/更新为新的Fragment
         * @param oldFragment 旧Fragment
         * @param newFragment 新Fragment
         */
        public void replaceFragment(Fragment oldFragment, Fragment newFragment) {
            int position = mFragmentList.indexOf(oldFragment);
            if (position == -1) {
                return;
            }
            //从Transaction移除旧的Fragment
            removeFragmentInternal(oldFragment);
            //替换List中对应的Fragment
            mFragmentList.set(position, newFragment);
            //刷新Adapter
            notifyItemChanged();
        }
    
        /**
         * 将指定位置的Fragment替换/更新为新的Fragment，同{@link #replaceFragment(BaseFragment oldFragment, BaseFragment newFragment)}
         * @param position    旧Fragment的位置
         * @param newFragment 新Fragment
         */
        public void replaceFragment(int position, Fragment newFragment) {
            Fragment oldFragment = mFragmentList.get(position);
            removeFragmentInternal(oldFragment);
            mFragmentList.set(position, newFragment);
            notifyItemChanged();
        }
    
        /**
         * 移除指定的Fragment
         * @param fragment 目标Fragment
         */
        public void removeFragment(Fragment fragment) {
            //先从List中移除
            mFragmentList.remove(fragment);
            //然后从Transaction移除
            removeFragmentInternal(fragment);
            //最后刷新Adapter
            notifyItemChanged();
        }
    
        /**
         * 移除指定位置的Fragment，同 {@link #removeFragment(BaseFragment fragment)}
         * @param position
         */
        public void removeFragment(int position) {
            Fragment fragment = mFragmentList.get(position);
            //然后从List中移除
            mFragmentList.remove(fragment);
            //先从Transaction移除
            removeFragmentInternal(fragment);
            //最后刷新Adapter
            notifyItemChanged();
        }
    
        /**
         * 添加Fragment
         * @param fragment 目标Fragment
         */
        public void addFragment(Fragment fragment) {
            mFragmentList.add(fragment);
            notifyItemChanged();
        }
    
        /**
         * 在指定位置插入一个Fragment
         * @param position 插入位置
         * @param fragment 目标Fragment
         */
        public void insertFragment(int position, Fragment fragment) {
            mFragmentList.add(position, fragment);
            notifyItemChanged();
        }
    
        private void notifyItemChanged() {
            //刷新之前重新收集位置信息
            setFragmentPositionMapForUpdate();
            notifyDataSetChanged();
            setFragmentPositionMap();
        }
    
        /**
         * 从Transaction移除Fragment
         * @param fragment 目标Fragment
         */
        private void removeFragmentInternal(Fragment fragment) {
            FragmentTransaction transaction = mFragmentManager.beginTransaction();
            transaction.remove(fragment);
    //        transaction.commitNow();
            transaction.commitNow();
        }
    
        /**
         * 此方法不用position做返回值即可破解fragment tag异常的错误
         */
        @Override
        public long getItemId(int position) {
            // 获取当前数据的hashCode，其实这里不用hashCode用自定义的可以关联当前Item对象的唯一值也可以，只要不是直接返回position
            return mFragmentList.get(position).hashCode();
        }
    
        @Override
        public Fragment getItem(int position) {
            return mFragmentList.get(position);
        }
    
        @Override
        public int getCount() {
            return mFragmentList.size();
        }
    
        public List<Fragment> getFragments() {
            return mFragmentList;
        }
    }