先看下这样一段代码
private String titles[] = new String[]{"今天", "这周", "这月", "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};
我们定义了一些要使用的fragment，并且使用viewPager展示出来了。由于viewPager自身的缓存机制和预加载机制导致这样的一个问题。
当我们请求接口请求一些数据回来要以后，想要更新某个fragment，但是界面数据总是更新失败。
那么这样的问题据我研究之后要这样来解决：
原理就是把就旧的fragment去除掉，换成新的fragment就OK了。
具体实现方法为重写adapter的 instantiateItem()方法。
@Override
public Object instantiateItem(ViewGroup container, int position) {
//得到缓存的fragment
Fragment fragment= (Fragment) super.instantiateItem(container, position);
//获取到tag
String fragmentTag=fragment.getTag();
if (fragmentsUpdateFlag[position % fragmentsUpdateFlag.length]){//如果这个fragment需要更新
android.support.v4.app.FragmentTransaction ft=fm.beginTransaction();
//移除旧的fragment
ft.remove(fragment);
//换成新的fragment
fragment = fragments[position % fragments.length];
//添加新fragment时必须用前面获得的tag，这点很重要
ft.add(container.getId(), fragment, fragmentTag ==null? fragment.getClass().getName()+position : fragmentTag);
ft.attach(fragment);
ft.commit();
//复位更新标志
fragmentsUpdateFlag[position % fragmentsUpdateFlag.length] = false;
}
return fragment;
}
下面贴出这个activity的全部的代码以供自己查阅：
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", "这周", "这月", "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 :当前页面，及你点击滑动的页面；arg1:当前页面偏移的百分比；arg2:当前页面偏移的像素位置
}
@Override
public void onPageSelected(int position) {
// arg0是当前选中的页面的Position
switch (position) {
case 0: //今天
break;
}
}
@Override
public void onPageScrollStateChanged(int state) {
//arg0 ==1的时表示正在滑动，arg0==2的时表示滑动完毕了，arg0==0的时表示什么都没做。
}
});
}
/**
* 请求网络数据
* @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发送数据跟新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) {
//得到缓存的fragment
Fragment fragment = (Fragment) super.instantiateItem(container, position);
//获取到tag
String fragmentTag = fragment.getTag();
if (fragmentsUpdateFlag[position % fragmentsUpdateFlag.length]) {//如果这个fragment需要更新
android.support.v4.app.FragmentTransaction ft = fm.beginTransaction();
//移除旧的fragment
ft.remove(fragment);
//换成新的fragment
fragment = fragments[position % fragments.length];
//添加新fragment时必须用前面获得的tag，这点很重要
ft.add(container.getId(), fragment, fragmentTag == null ? fragment.getClass().getName() + position : fragmentTag);
ft.attach(fragment);
ft.commit();
//复位更新标志
fragmentsUpdateFlag[position % fragmentsUpdateFlag.length] = false;
}
return fragment;
}
}
}
时间： 2024-10-24 23:22:14