TabLayout+ViewPager更新fragment的ui數據
阿新 • • 發佈：2017-09-23
back ges tool layout handler tle tex bindview bing
先看下這樣一段代碼
private String titles[] = new String[]{"今天", "這周", "這月", "今年"}; boolean[] fragmentsUpdateFlag = { false, false, false, false }; StarFragment todatFragmet=new StarFragment(titles[0],starDetailEntity, AppConstants.TYPE_CONTENT_TODAY); StarFragment weekFragmet=new StarFragment(titles[1],starDetailEntity, AppConstants.TYPE_CONTENT_WEEK); StarFragment monthFragmet=new StarFragment(titles[2],starDetailEntity, AppConstants.TYPE_CONTENT_MONTH); StarFragment yearFragmet=new StarFragment(titles[3],starDetailEntity, AppConstants.TYPE_CONTENT_YEAR); BaseFragment fragments[]={todatFragmet,weekFragmet,monthFragmet,yearFragmet};
我們定義了一些要使用的fragment，並且使用viewPager展示出來了。由於viewPager自身的緩存機制和預加載機制導致這樣的一個問題。
當我們請求接口請求一些數據回來要以後，想要更新某個fragment，但是界面數據總是更新失敗。
那麽這樣的問題據我研究之後要這樣來解決：
原理就是把就舊的fragment去除掉，換成新的fragment就OK了。
具體實現方法為重寫adapter的 instantiateItem()方法。
@Override public Object instantiateItem(ViewGroup container, int position) { //得到緩存的fragment Fragment fragment= (Fragment) super.instantiateItem(container, position); //獲取到tag String fragmentTag=fragment.getTag(); if (fragmentsUpdateFlag[position % fragmentsUpdateFlag.length]){//如果這個fragment需要更新 android.support.v4.app.FragmentTransaction ft=fm.beginTransaction(); //移除舊的fragment ft.remove(fragment); //換成新的fragment fragment = fragments[position % fragments.length]; //添加新fragment時必須用前面獲得的tag，這點很重要 ft.add(container.getId(), fragment, fragmentTag ==null? fragment.getClass().getName()+position : fragmentTag); ft.attach(fragment); ft.commit(); //復位更新標誌 fragmentsUpdateFlag[position % fragmentsUpdateFlag.length] = false; } return fragment; }
下面貼出這個activity的全部的代碼以供自己查閱：
import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.support.annotation.Nullable; import android.support.design.widget.TabLayout; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.ViewPager; import android.util.Log; import android.view.ViewGroup; import com.bingo.cqtimelottery.R; import com.bingo.cqtimelottery.api.ApiService; import com.bingo.cqtimelottery.api.RetrofitManager; import com.bingo.cqtimelottery.base.BaseActivity; import com.bingo.cqtimelottery.base.BaseFragment; import com.bingo.cqtimelottery.constants.ApiConstant; import com.bingo.cqtimelottery.constants.AppConstants; import com.bingo.cqtimelottery.starfortune.entity.StarDetailEntity; import com.bingo.cqtimelottery.util.DateUtil; import java.util.HashMap; import java.util.Map; import butterknife.BindView; import retrofit2.Call; import retrofit2.Callback; import retrofit2.Response; public class StarFortuneDetailActivity extends BaseActivity { @BindView(R.id.tabLayout) TabLayout mTabLayout; @BindView(R.id.viewPager) ViewPager mViewPager; private String titles[] = new String[]{"今天", "這周", "這月", "今年"}; boolean[] fragmentsUpdateFlag = {false, false, false, false}; StarFragment todatFragmet = new StarFragment(titles[0], starDetailEntity, AppConstants.TYPE_CONTENT_TODAY); StarFragment weekFragmet = new StarFragment(titles[1], starDetailEntity, AppConstants.TYPE_CONTENT_WEEK); StarFragment monthFragmet = new StarFragment(titles[2], starDetailEntity, AppConstants.TYPE_CONTENT_MONTH); StarFragment yearFragmet = new StarFragment(titles[3], starDetailEntity, AppConstants.TYPE_CONTENT_YEAR); BaseFragment fragments[] = {todatFragmet, weekFragmet, monthFragmet, yearFragmet}; private String starName; private String starId; public static StarDetailEntity starDetailEntity; StarPagerFragmentAdapter mainAdapter; private Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { super.handleMessage(msg); if (msg.arg1 == 100) { fragments[0] = new StarFragment(titles[0], starDetailEntity, AppConstants.TYPE_CONTENT_TODAY); fragmentsUpdateFlag[0] = true; mainAdapter.notifyDataSetChanged(); } } }; public static StarDetailEntity getStarDetailEntity() { return starDetailEntity; } public static void setStarDetailEntity(StarDetailEntity starDetailEntity) { StarFortuneDetailActivity.starDetailEntity = starDetailEntity; } @Override public int getLayoutRes() { return R.layout.activity_star_fortune_detail; } @Override public void onCreateActivity(@Nullable Bundle savedInstanceState) { Bundle bundle = getIntent().getExtras(); starName = bundle.getString("starName"); starId = bundle.getString("starId"); initToolbar(starName); initAdapter(); getStarDetailInfo(starId); } private void initAdapter() { mainAdapter = new StarPagerFragmentAdapter(getSupportFragmentManager(), fragments, titles); mViewPager.setAdapter(mainAdapter); mTabLayout.setupWithViewPager(mViewPager); mViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() { @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { // arg0 :當前頁面，及你點擊滑動的頁面；arg1:當前頁面偏移的百分比；arg2:當前頁面偏移的像素位置 } @Override public void onPageSelected(int position) { // arg0是當前選中的頁面的Position switch (position) { case 0: //今天 break; } } @Override public void onPageScrollStateChanged(int state) { //arg0 ==1的時表示正在滑動，arg0==2的時表示滑動完畢了，arg0==0的時表示什麽都沒做。 } }); } /** * 請求網絡數據 * @param lotteryid */ private void getStarDetailInfo(String lotteryid) { showLoading(); Map<String, String> map = new HashMap<>(); map.put("astroid", lotteryid); map.put("date", DateUtil.formateDateString().substring(0, 10)); map.put("appkey", ApiConstant.API_KEY); RetrofitManager.getInstance().createReq(ApiService.class) .loadStarDetailInfo(map) .enqueue(new Callback<StarDetailEntity>() { @Override public void onResponse(Call<StarDetailEntity> call, Response<StarDetailEntity> response) { dismissLoading(); if (response.body() != null) starDetailEntity = response.body(); //使用Handler發送數據跟新UI Message message = new Message(); message.arg1 = 100; mHandler.sendMessage(message); } @Override public void onFailure(Call<StarDetailEntity> call, Throwable t) { } }); } private void replaceTodayFragment() { } public class StarPagerFragmentAdapter<T extends Fragment> extends FragmentPagerAdapter { private BaseFragment[] mList; private String[] mTitles; private StarDetailEntity starDetailEntity; private FragmentManager fm; public StarDetailEntity getStarDetailEntity() { return starDetailEntity; } public void setStarDetailEntity(StarDetailEntity starDetailEntity) { this.starDetailEntity = starDetailEntity; } public StarPagerFragmentAdapter(FragmentManager fm, BaseFragment[] list, String[] titles) { super(fm); this.mList = list; this.mTitles = titles; this.fm = fm; } @Override public Fragment getItem(int position) { Fragment fragment = fragments[position % fragments.length]; Log.i("zzccbb", "getItem:position=" + position + ",fragment:" + fragment.getClass().getName() + ",fragment.tag=" + fragment.getTag()); return fragments[position % fragments.length]; } @Override public int getItemPosition(Object object) { return POSITION_NONE; } @Override public int getCount() { return mList.length; } @Override public CharSequence getPageTitle(int position) { return mTitles == null ? super.getPageTitle(position) : mTitles[position]; } @Override public Object instantiateItem(ViewGroup container, int position) { //得到緩存的fragment Fragment fragment = (Fragment) super.instantiateItem(container, position); //獲取到tag String fragmentTag = fragment.getTag(); if (fragmentsUpdateFlag[position % fragmentsUpdateFlag.length]) {//如果這個fragment需要更新 android.support.v4.app.FragmentTransaction ft = fm.beginTransaction(); //移除舊的fragment ft.remove(fragment); //換成新的fragment fragment = fragments[position % fragments.length]; //添加新fragment時必須用前面獲得的tag，這點很重要 ft.add(container.getId(), fragment, fragmentTag == null ? fragment.getClass().getName() + position : fragmentTag); ft.attach(fragment); ft.commit(); //復位更新標誌 fragmentsUpdateFlag[position % fragmentsUpdateFlag.length] = false; } return fragment; } } }
TabLayout+ViewPager更新fragment的ui數據