1、博文介绍
2、FragmentPagerAdapter中设置不让Fragment视图重新创建
image.png
image.png
FragmentPagerAdapter完整代码如下
/**
* 主页ViewPager适配器
* Created by _Smile on 2017/5/9.
*/
public class TabFragmentPagerAdapter extends FragmentPagerAdapter {
private FragmentManager mFragmentManager;
//保存每个Fragment的Tag，刷新页面的依据
protected SparseArray tags = new SparseArray<>();
//继承FragmentPagerAdapter类 ,并自定义的构造器
private List fragments;
public TabFragmentPagerAdapter(FragmentManager fm, List fragments) {
super(fm);
this.fragments =fragments;
mFragmentManager = fm;
}
@Override
public Fragment getItem(int position) {
return fragments.get(position);
}
@Override
public int getCount() {
return fragments.size();
}
@Override
public long getItemId(int position) {
return fragments.get(position).hashCode();
}
@Override
public int getItemPosition(Object object) {
Fragment fragment = (Fragment) object;
//如果Item对应的Tag存在，则不进行刷新
if (tags.indexOfValue(fragment.getTag()) > -1) {
return super.getItemPosition(object);
}
return POSITION_NONE;
}
@Override
public Object instantiateItem(ViewGroup container, int position) {
//得到缓存的fragment
Fragment fragment = (Fragment) super.instantiateItem(container, position);
String tag = fragment.getTag();
//保存每个Fragment的Tag
tags.put(position, tag);
return fragment;
}
//拿到指定位置的Fragment
public Fragment getFragmentByPosition(int position) {
return mFragmentManager.findFragmentByTag(tags.get(position));
}
public List getFragments(){
return mFragmentManager.getFragments();
}
//刷新指定位置的Fragment
public void notifyFragmentByPosition(int position) {
tags.removeAt(position);
notifyDataSetChanged();
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
// super.destroyItem(container, position, object);
}
@Override
public void notifyDataSetChanged() {
super.notifyDataSetChanged();
}
}
Fragmenr和Activity使用代码如下
mFragments.add(mTab_01);
mFragments.add(mTab_02);
mFragments.add(mTab_03);
mAdapter = new TabFragmentPagerAdapter(getSupportFragmentManager(), mFragments);
mViewPager.setOffscreenPageLimit(mFragments.size());
//设置滑动监听器
mViewPager.clearOnPageChangeListeners();
mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
//滑动时 改变图标状态
@Override
public void onPageSelected(int position) {
int currentItem = mViewPager.getCurrentItem();
LogUtils.d(“当前currentItem:” + currentItem + “当前position:” + position);
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
……
mViewPager.setAdapter(mAdapter);
mViewPager.setCurrentItem(0);
setSelect(0);