小編這次要給大家分享的是解決androidx下的fragment的lazy懶加載問(wèn)題，文章內(nèi)容豐富，感興趣的小伙伴可以來(lái)了解一下，希望大家閱讀完這篇文章之后能夠有所收獲。
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一、前置準(zhǔn)備工作
幾個(gè)關(guān)于androidx的fragment懶加載方案，都離不開(kāi)如下幾個(gè)包：
我在實(shí)際測(cè)試代碼中使用了如下版本，可供參考：
還準(zhǔn)備了4個(gè)Activity與5個(gè)Fragment：
相應(yīng)的幾個(gè)簡(jiǎn)單布局文件:
文件：fragment_main.xml
加載ViewPager控件和AddShow使用的FrameLayout，以及測(cè)試跳轉(zhuǎn)后返回的TextView按鈕。
fragment_main.xml
<?xml version="1.0" encoding="utf-8"?>
文件：activity_lazy_fragment.xml
這里是測(cè)試fragment嵌套情況下的布局，fl_content用來(lái)加載fragment
activity_lazy_fragment.xml
<?xml version="1.0" encoding="utf-8"?>
文件：fragment_blank.xml
這一個(gè)空f(shuō)ragment就沒(méi)什么講究了
fragment_blank.xml
<?xml version="1.0" encoding="utf-8"?>
二、具體代碼分析
1) ViewPager+Fragment
最常見(jiàn)的使用方式，由ViewPager滑動(dòng)顯示多個(gè)Fragment，直接上代碼：
activity頁(yè)面代碼
其中就是個(gè)簡(jiǎn)單的viewpager設(shè)置adapter然后加載fragment集合顯示
重慶分公司
重慶分公司
/**
* viewpager內(nèi)的fragment懶加載
*/
public class ViewPagerFragmentActivity extends BindActivity implements BlankFragment1.OnFragmentInteractionListener , BlankFragment2.OnFragmentInteractionListener, BlankFragment3.OnFragmentInteractionListener {
private static final String KEY_FRAGMENT_1 = "1";
private static final String KEY_FRAGMENT_2 = "2";
private static final String KEY_FRAGMENT_3 = "3";
@BindView(R.id.vp_fragment)
ViewPager vp;
@BindView(R.id.tv_next)
TextView tv_next;
BlankFragment1 blankFragment1;
BlankFragment2 blankFragment2;
BlankFragment3 blankFragment3;
List fragmentList;
@Override
protected int setLayoutID() {
return R.layout.fragment_main;
}
@Override
protected void initViews(Bundle savedInstanceState) {
tv_next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent(mContext, MMKVActivity.class);
startActivity(intent);
}
});
if(savedInstanceState != null){
blankFragment1 = (BlankFragment1)getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_1);
blankFragment2 = (BlankFragment2)getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_2);
blankFragment3 = (BlankFragment3)getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_3);
}
fragmentList=new ArrayList<>();
if (blankFragment1==null){
fragmentList.add(blankFragment1=BlankFragment1.newInstance("11111",""));
}else {
fragmentList.add(blankFragment1);
}
if (blankFragment2==null){
fragmentList.add(blankFragment2=BlankFragment2.newInstance("22222",""));
}else {
fragmentList.add(blankFragment2);
}
if (blankFragment3==null){
fragmentList.add(blankFragment3=BlankFragment3.newInstance("333333",""));
}else {
fragmentList.add(blankFragment3);
}
vp.setAdapter(new BaseFragmentXPagerAdapter(getSupportFragmentManager(),fragmentList,null));
}
@Override
public void onFragmentInteraction(Uri uri) {
}
@Override
protected void onSaveInstanceState(Bundle outState) {
if(blankFragment1 != null&&blankFragment1.isAdded()) {
getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_1,blankFragment1);
}
if(blankFragment2 != null&&blankFragment2.isAdded()){
getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_2,blankFragment2);
}
if(blankFragment3 != null&&blankFragment3.isAdded()){
getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_3,blankFragment3);
}
super.onSaveInstanceState(outState);
}
} BaseFragmentXPagerAdapter頁(yè)面代碼
新版FragmentPagerAdapter多了2個(gè)常量
@Retention(RetentionPolicy.SOURCE)
@IntDef({BEHAVIOR_SET_USER_VISIBLE_HINT, BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT})
private @interface Behavior { }用在了構(gòu)造方法中
/**
* Constructor for {@link FragmentPagerAdapter}.
*
* If {@link #BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT} is passed in, then only the current
* Fragment is in the {@link Lifecycle.State#RESUMED} state. All other fragments are capped at
* {@link Lifecycle.State#STARTED}. If {@link #BEHAVIOR_SET_USER_VISIBLE_HINT} is passed, all
* fragments are in the {@link Lifecycle.State#RESUMED} state and there will be callbacks to
* {@link Fragment#setUserVisibleHint(boolean)}.
*
* @param fm fragment manager that will interact with this adapter
* @param behavior determines if only current fragments are in a resumed state
*/
public FragmentPagerAdapter(@NonNull FragmentManager fm,
@Behavior int behavior) {
mFragmentManager = fm;
mBehavior = behavior;
}我們只需要在構(gòu)造adapter時(shí)，使用BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT這個(gè)常量就行
/**
* support lazy init
*/
public class BaseFragmentXPagerAdapter extends FragmentPagerAdapter {
private List mFragmentList = new ArrayList<>();
private List mFragmentTitleList = new ArrayList<>();
public BaseFragmentXPagerAdapter(@NonNull FragmentManager fm,List fragmentList,List fragmentTitleList) {
this(fm,fragmentList,fragmentTitleList,BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
}
public BaseFragmentXPagerAdapter(@NonNull FragmentManager fm,List fragmentList,List fragmentTitleList, int behavior) {
super(fm, behavior);
if (fragmentList!=null){
mFragmentList.addAll(fragmentList);
}
if (fragmentTitleList!=null){
mFragmentTitleList.addAll(fragmentTitleList);
}
}
public BaseFragmentXPagerAdapter(@NonNull FragmentManager fm,Fragment[] fragmentList,String[] fragmentTitleList) {
this(fm,fragmentList,fragmentTitleList,BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
}
public BaseFragmentXPagerAdapter(@NonNull FragmentManager fm,Fragment[] fragmentList,String[] fragmentTitleList, int behavior) {
super(fm, behavior);
if (fragmentList!=null){
for (int i = 0; i < fragmentList.length; i++) {
mFragmentList.add(fragmentList[i]);
}
}
if (fragmentTitleList!=null){
for (int i = 0; i < fragmentTitleList.length; i++) {
mFragmentTitleList.add(fragmentTitleList[i]);
}
}
}
@NonNull
@Override
public Fragment getItem(int position) {
if (mFragmentList!=null&&!mFragmentList.isEmpty()){
return mFragmentList.get(position);
}else {
return null;
}
}
@Override
public int getCount() {
if (mFragmentList!=null&&!mFragmentList.isEmpty()){
return mFragmentList.size();
}else {
return 0;
}
}
@Nullable
@Override
public CharSequence getPageTitle(int position) {
if (mFragmentTitleList!=null&&!mFragmentTitleList.isEmpty()&&position 最終打印生命周期日志，確認(rèn)結(jié)果，viewPager+fragment搭配pagerAdapter的behavior在各種情況下的日志，可以看出新版viewPager+pagerAdapter實(shí)測(cè)下來(lái)，Fragment的onResume生命周期只會(huì)在當(dāng)前頁(yè)顯示時(shí)調(diào)用：
首次進(jìn)入 顯示第一頁(yè)
ViewPagerFragmentActivity--->onCreate
ViewPagerFragmentActivity--->onStart
ViewPagerFragmentActivity--->onResume
BlankFragment1--->onAttach
BlankFragment1--->onCreate
BlankFragment2--->onAttach
BlankFragment2--->onCreate
BlankFragment1--->onViewCreated
BlankFragment1--->onActivityCreated
BlankFragment1--->onStart
BlankFragment2--->onViewCreated
BlankFragment2--->onActivityCreated
BlankFragment2--->onStart
BlankFragment1--->onResume <<=================== 當(dāng)前頁(yè)
滑動(dòng)到第二頁(yè)
BlankFragment3--->onAttach
BlankFragment3--->onCreate
BlankFragment3--->onViewCreated
BlankFragment3--->onActivityCreated
BlankFragment3--->onStart
BlankFragment1--->onPause
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
鎖屏
BlankFragment2--->onPause
ViewPagerFragmentActivity--->onPause
BlankFragment1--->onStop
BlankFragment2--->onStop
BlankFragment3--->onStop
ViewPagerFragmentActivity--->onStop
ViewPagerFragmentActivity--->onSaveInstanceState
解鎖屏幕
ViewPagerFragmentActivity--->onRestart
BlankFragment1--->onStart
BlankFragment2--->onStart
BlankFragment3--->onStart
ViewPagerFragmentActivity--->onStart
ViewPagerFragmentActivity--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
HOME回到桌面
BlankFragment2--->onPause
ViewPagerFragmentActivity--->onPause
BlankFragment1--->onStop
BlankFragment2--->onStop
BlankFragment3--->onStop
ViewPagerFragmentActivity--->onStop
ViewPagerFragmentActivity--->onSaveInstanceState
返回app頁(yè)面
ViewPagerFragmentActivity--->onRestart
BlankFragment1--->onStart
BlankFragment2--->onStart
BlankFragment3--->onStart
ViewPagerFragmentActivity--->onStart
ViewPagerFragmentActivity--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
跳轉(zhuǎn)新頁(yè)面
BlankFragment2--->onPause
ViewPagerFragmentActivity--->onPause
MMKVActivity--->onCreate
MMKVActivity--->onStart
MMKVActivity--->onResume
BlankFragment1--->onStop
BlankFragment2--->onStop
BlankFragment3--->onStop
ViewPagerFragmentActivity--->onStop
ViewPagerFragmentActivity--->onSaveInstanceState
返回ViewPager的頁(yè)面
MMKVActivity--->onPause
ViewPagerFragmentActivity--->onRestart
BlankFragment1--->onStart
BlankFragment2--->onStart
BlankFragment3--->onStart
ViewPagerFragmentActivity--->onStart
ViewPagerFragmentActivity--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
MMKVActivity--->onStop
MMKVActivity--->onDestroy
2) Fragment嵌套Fragment內(nèi)的ViewPager+Fragment
外層的activity只是add一個(gè)fragment
/**
* fragment內(nèi)的viewpager內(nèi)的fragment懶加載
*/
public class ViewPagerFragmentInFragmentActivity extends BindActivity implements ViewPagerFragmentInFragment.OnFragmentInteractionListener ,BlankFragment1.OnFragmentInteractionListener, BlankFragment2.OnFragmentInteractionListener, BlankFragment3.OnFragmentInteractionListener {
@Override
protected int setLayoutID() {
return R.layout.activity_lazy_fragment;
}
@Override
protected void initViews(Bundle savedInstanceState) {
FragmentTransaction transaction=getSupportFragmentManager().beginTransaction();
transaction.add(R.id.fl_content, ViewPagerFragmentInFragment.newInstance("",""));
transaction.commit();
}
@Override
public void onFragmentInteraction(Uri uri) {
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
}嵌套用的fragment類，ViewPagerFragmentInFragment
/**
* viewpager在一個(gè)fragment內(nèi)
*/
public class ViewPagerFragmentInFragment extends BaseFragment {
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
private static final String KEY_FRAGMENT_1 = "1";
private static final String KEY_FRAGMENT_2 = "2";
private static final String KEY_FRAGMENT_3 = "3";
@BindView(R.id.vp_fragment)
ViewPager vp;
@BindView(R.id.tv_next)
TextView tv_next;
BlankFragment1 blankFragment1;
BlankFragment2 blankFragment2;
BlankFragment3 blankFragment3;
List fragmentList;
public ViewPagerFragmentInFragment() {
}
public static ViewPagerFragmentInFragment newInstance(String param1, String param2) {
ViewPagerFragmentInFragment fragment = new ViewPagerFragmentInFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
if(blankFragment1 != null&&blankFragment1.isAdded()) {
mActivity.getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_1,blankFragment1);
}
if(blankFragment2 != null&&blankFragment2.isAdded()){
mActivity.getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_2,blankFragment2);
}
if(blankFragment3 != null&&blankFragment3.isAdded()){
mActivity.getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_3,blankFragment3);
}
super.onSaveInstanceState(outState);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
tv_next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent(mContext, MMKVActivity.class);
startActivity(intent);
}
});
if(savedInstanceState != null){
blankFragment1 = (BlankFragment1)mActivity.getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_1);
blankFragment2 = (BlankFragment2)mActivity.getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_2);
blankFragment3 = (BlankFragment3)mActivity.getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_3);
}
fragmentList=new ArrayList<>();
if (blankFragment1==null){
fragmentList.add(blankFragment1=BlankFragment1.newInstance("11111",""));
}else {
fragmentList.add(blankFragment1);
}
if (blankFragment2==null){
fragmentList.add(blankFragment2=BlankFragment2.newInstance("22222",""));
}else {
fragmentList.add(blankFragment2);
}
if (blankFragment3==null){
fragmentList.add(blankFragment3=BlankFragment3.newInstance("333333",""));
}else {
fragmentList.add(blankFragment3);
}
vp.setAdapter(new BaseFragmentXPagerAdapter(mActivity.getSupportFragmentManager(),fragmentList,null));
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_main, container, false);
}
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
void onFragmentInteraction(Uri uri);
}
} 實(shí)測(cè)日志可以發(fā)現(xiàn)，哪怕fragment是嵌套過(guò)的，F(xiàn)ragment的onResume生命周期也只會(huì)在當(dāng)前頁(yè)顯示時(shí)調(diào)用：
首次進(jìn)入顯示第一頁(yè)
ViewPagerFragmentInFragment--->onStart
ViewPagerFragmentInFragmentActivity--->onStart
ViewPagerFragmentInFragmentActivity--->onResume
ViewPagerFragmentInFragment--->onResume
BlankFragment1--->onAttach
BlankFragment1--->onCreate
BlankFragment2--->onAttach
BlankFragment2--->onCreate
BlankFragment1--->onViewCreated
BlankFragment1--->onActivityCreated
BlankFragment1--->onStart
BlankFragment2--->onViewCreated
BlankFragment2--->onActivityCreated
BlankFragment2--->onStart
BlankFragment1--->onResume <<=================== 當(dāng)前頁(yè)
滑動(dòng)到第二頁(yè)
BlankFragment3--->onAttach
BlankFragment3--->onCreate
BlankFragment3--->onViewCreated
BlankFragment3--->onActivityCreated
BlankFragment3--->onStart
BlankFragment1--->onPause
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
鎖屏
ViewPagerFragmentInFragment--->onPause
BlankFragment2--->onPause
ViewPagerFragmentInFragmentActivity--->onPause
ViewPagerFragmentInFragment--->onStop
BlankFragment1--->onStop
BlankFragment2--->onStop
BlankFragment3--->onStop
ViewPagerFragmentInFragmentActivity--->onStop
ViewPagerFragmentInFragmentActivity--->onSaveInstanceState
解鎖屏幕
ViewPagerFragmentInFragmentActivity--->onRestart
ViewPagerFragmentInFragment--->onStart
BlankFragment1--->onStart
BlankFragment2--->onStart
BlankFragment3--->onStart
ViewPagerFragmentInFragmentActivity--->onStart
ViewPagerFragmentInFragmentActivity--->onResume
ViewPagerFragmentInFragment--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
HOME回到桌面
ViewPagerFragmentInFragment--->onPause
BlankFragment2--->onPause
ViewPagerFragmentInFragmentActivity--->onPause
ViewPagerFragmentInFragment--->onStop
BlankFragment1--->onStop
BlankFragment2--->onStop
BlankFragment3--->onStop
ViewPagerFragmentInFragmentActivity--->onStop
ViewPagerFragmentInFragmentActivity--->onSaveInstanceState
返回app頁(yè)面
ViewPagerFragmentInFragmentActivity--->onRestart
ViewPagerFragmentInFragment--->onStart
BlankFragment1--->onStart
BlankFragment2--->onStart
BlankFragment3--->onStart
ViewPagerFragmentInFragmentActivity--->onStart
ViewPagerFragmentInFragmentActivity--->onResume
ViewPagerFragmentInFragment--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
跳轉(zhuǎn)新頁(yè)面
ViewPagerFragmentInFragment--->onPause
BlankFragment2--->onPause
ViewPagerFragmentInFragmentActivity--->onPause
MMKVActivity--->onCreate
MMKVActivity--->onStart
MMKVActivity--->onResume
ViewPagerFragmentInFragment--->onStop
BlankFragment1--->onStop
BlankFragment2--->onStop
BlankFragment3--->onStop
ViewPagerFragmentInFragmentActivity--->onStop
ViewPagerFragmentInFragmentActivity--->onSaveInstanceState
返回ViewPager的頁(yè)面
MMKVActivity--->onPause
ViewPagerFragmentInFragmentActivity--->onRestart
ViewPagerFragmentInFragment--->onStart
BlankFragment1--->onStart
BlankFragment2--->onStart
BlankFragment3--->onStart
ViewPagerFragmentInFragmentActivity--->onStart
ViewPagerFragmentInFragmentActivity--->onResume
ViewPagerFragmentInFragment--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
3) 通過(guò)add show hide操作多個(gè)fragment
activity代碼中的一個(gè)細(xì)節(jié)為通過(guò)add show的頁(yè)面，設(shè)置transaction.setMaxLifecycle(fragment, Lifecycle.State.RESUMED)，讓該fragment的生命周期能順利走到resume；
通過(guò)hide隱藏的頁(yè)面，設(shè)置transaction.setMaxLifecycle(fragmentList.get(i), Lifecycle.State.CREATED)，使隱藏了的fragment生命周期只能走到創(chuàng)建階段，無(wú)法走到resume方法。
/**
* add show hide下的fragment懶加載
*/
public class AddShowHideFragmentActivity extends BindActivity implements BlankFragment1.OnFragmentInteractionListener , BlankFragment2.OnFragmentInteractionListener, BlankFragment3.OnFragmentInteractionListener {
private static final String KEY_FRAGMENT_1 = "1";
private static final String KEY_FRAGMENT_2 = "2";
private static final String KEY_FRAGMENT_3 = "3";
@BindView(R.id.tab_title)
CommonTabLayout commonTabLayout;
@BindView(R.id.tv_next)
TextView tv_next;
BlankFragment1 blankFragment1;
BlankFragment2 blankFragment2;
BlankFragment3 blankFragment3;
List fragmentList;
@Override
protected int setLayoutID() {
return R.layout.fragment_main;
}
@Override
protected void initViews(Bundle savedInstanceState) {
tv_next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent(mContext, MMKVActivity.class);
startActivity(intent);
}
});
if(savedInstanceState != null){
blankFragment1 = (BlankFragment1)getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_1);
blankFragment2 = (BlankFragment2)getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_2);
blankFragment3 = (BlankFragment3)getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_3);
}
fragmentList=new ArrayList<>();
if (blankFragment1==null){
fragmentList.add(blankFragment1=BlankFragment1.newInstance("11111",""));
}else {
fragmentList.add(blankFragment1);
}
if (blankFragment2==null){
fragmentList.add(blankFragment2=BlankFragment2.newInstance("22222",""));
}else {
fragmentList.add(blankFragment2);
}
if (blankFragment3==null){
fragmentList.add(blankFragment3=BlankFragment3.newInstance("33333",""));
}else {
fragmentList.add(blankFragment3);
}
ArrayList tabEntities = new ArrayList<>();
tabEntities.add(new TabLayoutEntity("商品1"));
tabEntities.add(new TabLayoutEntity("評(píng)價(jià)2"));
tabEntities.add(new TabLayoutEntity("詳情3"));
commonTabLayout.setTabData(tabEntities);
commonTabLayout.setCurrentTab(0);
showFragment(fragmentList.get(0),false);
commonTabLayout.setOnTabSelectListener(new OnTabSelectListener() {
@Override
public void onTabSelect(int position) {
showFragment(fragmentList.get(position),false);
}
@Override
public void onTabReselect(int position) {
showFragment(fragmentList.get(position),false);
}
});
}
private void showFragment(Fragment fragment,boolean replace){
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
if (replace){
transaction.replace(R.id.fl_in_content,fragment);
}else {
if (!fragment.isAdded()){
transaction.add(R.id.fl_in_content,fragment,fragment.getClass().getSimpleName());
}
hideAllFragment(transaction,fragment);
transaction.show(fragment);
transaction.setMaxLifecycle(fragment, Lifecycle.State.RESUMED);
}
transaction.commit();
}
private void hideAllFragment(FragmentTransaction transaction,Fragment withoutFragment){
for (int i = 0; i < fragmentList.size(); i++) {
if (!fragmentList.get(i).equals(withoutFragment)&&fragmentList.get(i).isAdded()){
transaction.hide(fragmentList.get(i));
transaction.setMaxLifecycle(fragmentList.get(i), Lifecycle.State.CREATED);
}
}
}
@Override
public void onFragmentInteraction(Uri uri) {
}
@Override
protected void onSaveInstanceState(Bundle outState) {
if(blankFragment1 != null&&blankFragment1.isAdded()) {
getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_1,blankFragment1);
}
if(blankFragment2 != null&&blankFragment2.isAdded()){
getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_2,blankFragment2);
}
if(blankFragment3 != null&&blankFragment3.isAdded()){
getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_3,blankFragment3);
}
super.onSaveInstanceState(outState);
}
} 首次進(jìn)入 顯示第一頁(yè)
AddShowHideFragmentActivity--->onCreate
BlankFragment1--->onAttach
BlankFragment1--->onCreate
BlankFragment1--->onViewCreated
BlankFragment1--->onActivityCreated
BlankFragment1--->onStart
AddShowHideFragmentActivity--->onStart
AddShowHideFragmentActivity--->onResume
BlankFragment1--->onResume <<=================== 當(dāng)前頁(yè)
點(diǎn)擊顯示第二頁(yè)
BlankFragment2--->onAttach
BlankFragment2--->onCreate
BlankFragment1--->onHiddenChanged=true
BlankFragment1--->onPause
BlankFragment1--->onStop
BlankFragment1--->onDestroyView
BlankFragment2--->onViewCreated
BlankFragment2--->onActivityCreated
BlankFragment2--->onStart
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
鎖屏
lankFragment2--->onPause
AddShowHideFragmentActivity--->onPause
BlankFragment2--->onStop
AddShowHideFragmentActivity--->onStop
AddShowHideFragmentActivity--->onSaveInstanceState
解鎖屏幕
AddShowHideFragmentActivity--->onRestart
BlankFragment2--->onStart
AddShowHideFragmentActivity--->onStart
AddShowHideFragmentActivity--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
HOME回到桌面
BlankFragment2--->onPause
AddShowHideFragmentActivity--->onPause
BlankFragment2--->onStop
AddShowHideFragmentActivity--->onStop
AddShowHideFragmentActivity--->onSaveInstanceState
返回app頁(yè)面
AddShowHideFragmentActivity--->onRestart
BlankFragment2--->onStart
AddShowHideFragmentActivity--->onStart
AddShowHideFragmentActivity--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
跳轉(zhuǎn)新頁(yè)面
BlankFragment2--->onPause
AddShowHideFragmentActivity--->onPause
MMKVActivity--->onCreate
MMKVActivity--->onStart
MMKVActivity--->onResume
BlankFragment2--->onStop
AddShowHideFragmentActivity--->onStop
AddShowHideFragmentActivity--->onSaveInstanceState
返回ViewPager的頁(yè)面
MMKVActivity--->onPause
AddShowHideFragmentActivity--->onRestart
BlankFragment2--->onStart
AddShowHideFragmentActivity--->onStart
AddShowHideFragmentActivity--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
4) Fragment嵌套Fragment內(nèi)的add show hide Fragment
外層的activity只是add一個(gè)fragment
/**
* fragment內(nèi)的viewpager內(nèi)的fragment懶加載
*/
public class AddShowHideFragmentInFragmentActivity extends BindActivity implements AddFragmentInFragment.OnFragmentInteractionListener ,BlankFragment1.OnFragmentInteractionListener, BlankFragment2.OnFragmentInteractionListener, BlankFragment3.OnFragmentInteractionListener {
@Override
protected int setLayoutID() {
return R.layout.activity_lazy_fragment;
}
@Override
protected void initViews(Bundle savedInstanceState) {
FragmentTransaction transaction=getSupportFragmentManager().beginTransaction();
transaction.add(R.id.fl_content,AddFragmentInFragment.newInstance("",""));
transaction.commit();
}
@Override
public void onFragmentInteraction(Uri uri) {
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
}內(nèi)部的fragment代碼如下
/**
* add hide show顯示的fragment 嵌套在 外層fragment內(nèi)
*/
public class AddFragmentInFragment extends BaseFragment {
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
private static final String KEY_FRAGMENT_1 = "1";
private static final String KEY_FRAGMENT_2 = "2";
private static final String KEY_FRAGMENT_3 = "3";
@BindView(R.id.tab_title)
CommonTabLayout commonTabLayout;
@BindView(R.id.tv_next)
TextView tv_next;
BlankFragment1 blankFragment1;
BlankFragment2 blankFragment2;
BlankFragment3 blankFragment3;
List fragmentList;
public AddFragmentInFragment() {
}
public static AddFragmentInFragment newInstance(String param1, String param2) {
AddFragmentInFragment fragment = new AddFragmentInFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onSaveInstanceState(@NonNull Bundle outState) {
if(blankFragment1 != null&&blankFragment1.isAdded()) {
mActivity.getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_1,blankFragment1);
}
if(blankFragment2 != null&&blankFragment2.isAdded()){
mActivity.getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_2,blankFragment2);
}
if(blankFragment3 != null&&blankFragment3.isAdded()){
mActivity.getSupportFragmentManager().putFragment(outState,KEY_FRAGMENT_3,blankFragment3);
}
super.onSaveInstanceState(outState);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
tv_next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent(mContext, MMKVActivity.class);
startActivity(intent);
}
});
if(savedInstanceState != null){
blankFragment1 = (BlankFragment1)mActivity.getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_1);
blankFragment2 = (BlankFragment2)mActivity.getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_2);
blankFragment3 = (BlankFragment3)mActivity.getSupportFragmentManager().getFragment(savedInstanceState,KEY_FRAGMENT_3);
}
fragmentList=new ArrayList<>();
if (blankFragment1==null){
fragmentList.add(blankFragment1=BlankFragment1.newInstance("11111",""));
}else {
fragmentList.add(blankFragment1);
}
if (blankFragment2==null){
fragmentList.add(blankFragment2=BlankFragment2.newInstance("222222",""));
}else {
fragmentList.add(blankFragment2);
}
if (blankFragment3==null){
fragmentList.add(blankFragment3=BlankFragment3.newInstance("3333333",""));
}else {
fragmentList.add(blankFragment3);
}
ArrayList tabEntities = new ArrayList<>();
tabEntities.add(new TabLayoutEntity("商品1"));
tabEntities.add(new TabLayoutEntity("評(píng)價(jià)2"));
tabEntities.add(new TabLayoutEntity("詳情3"));
commonTabLayout.setTabData(tabEntities);
commonTabLayout.setCurrentTab(0);
showFragment(fragmentList.get(0),false);
commonTabLayout.setOnTabSelectListener(new OnTabSelectListener() {
@Override
public void onTabSelect(int position) {
showFragment(fragmentList.get(position),false);
}
@Override
public void onTabReselect(int position) {
showFragment(fragmentList.get(position),false);
}
});
}
private void showFragment(Fragment fragment,boolean replace){
FragmentTransaction transaction = mActivity.getSupportFragmentManager().beginTransaction();
if (replace){
transaction.replace(R.id.fl_in_content,fragment);
}else {
if (!fragment.isAdded()){
transaction.add(R.id.fl_in_content,fragment,fragment.getClass().getSimpleName());
}
hideAllFragment(transaction,fragment);
transaction.show(fragment);
transaction.setMaxLifecycle(fragment, Lifecycle.State.RESUMED);
}
transaction.commit();
}
private void hideAllFragment(FragmentTransaction transaction,Fragment withoutFragment){
for (int i = 0; i < fragmentList.size(); i++) {
if (!fragmentList.get(i).equals(withoutFragment)&&fragmentList.get(i).isAdded()){
transaction.hide(fragmentList.get(i));
transaction.setMaxLifecycle(fragmentList.get(i), Lifecycle.State.CREATED);
}
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_main, container, false);
}
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
public interface OnFragmentInteractionListener {
void onFragmentInteraction(Uri uri);
}
} 實(shí)測(cè)日志可以發(fā)現(xiàn)，哪怕fragment是嵌套過(guò)的，F(xiàn)ragment的onResume生命周期也只會(huì)在當(dāng)前頁(yè)顯示時(shí)調(diào)用：
首次進(jìn)入 顯示第一頁(yè)
AddShowHideFragmentInFragmentActivity--->onCreate
AddFragmentInFragment--->onAttach
AddFragmentInFragment--->onCreate
AddFragmentInFragment--->onViewCreated
AddFragmentInFragment--->onActivityCreated
BlankFragment1--->onAttach
BlankFragment1--->onCreate
BlankFragment1--->onViewCreated
BlankFragment1--->onActivityCreated
AddFragmentInFragment--->onStart
BlankFragment1--->onStart
AddShowHideFragmentInFragmentActivity--->onStart
AddShowHideFragmentInFragmentActivity--->onResume
AddFragmentInFragment--->onResume
BlankFragment1--->onResume <<=================== 當(dāng)前頁(yè)
點(diǎn)擊顯示第二頁(yè)
BlankFragment2--->onAttach
BlankFragment2--->onCreate
BlankFragment1--->onHiddenChanged=true
BlankFragment1--->onPause
BlankFragment1--->onStop
BlankFragment1--->onDestroyView
BlankFragment2--->onViewCreated
BlankFragment2--->onActivityCreated
BlankFragment2--->onStart
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
鎖屏
AddFragmentInFragment--->onPause
BlankFragment2--->onPause
AddShowHideFragmentInFragmentActivity--->onPause
AddFragmentInFragment--->onStop
BlankFragment2--->onStop
AddShowHideFragmentInFragmentActivity--->onStop
AddShowHideFragmentInFragmentActivity--->onSaveInstanceState
解鎖屏幕
AddShowHideFragmentInFragmentActivity--->onRestart
AddFragmentInFragment--->onStart
BlankFragment2--->onStart
AddShowHideFragmentInFragmentActivity--->onStart
AddShowHideFragmentInFragmentActivity--->onResume
AddFragmentInFragment--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
HOME回到桌面
AddFragmentInFragment--->onPause
BlankFragment2--->onPause
AddShowHideFragmentInFragmentActivity--->onPause
AddFragmentInFragment--->onStop
BlankFragment2--->onStop
AddShowHideFragmentInFragmentActivity--->onStop
AddShowHideFragmentInFragmentActivity--->onSaveInstanceState
返回app頁(yè)面
AddShowHideFragmentInFragmentActivity--->onRestart
AddFragmentInFragment--->onStart
BlankFragment2--->onStart
AddShowHideFragmentInFragmentActivity--->onStart
AddShowHideFragmentInFragmentActivity--->onResume
AddFragmentInFragment--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
跳轉(zhuǎn)新頁(yè)面
AddFragmentInFragment--->onPause
BlankFragment2--->onPause
AddShowHideFragmentInFragmentActivity--->onPause
MMKVActivity--->onCreate
MMKVActivity--->onStart
MMKVActivity--->onResume
AddFragmentInFragment--->onStop
BlankFragment2--->onStop
AddShowHideFragmentInFragmentActivity--->onStop
AddShowHideFragmentInFragmentActivity--->onSaveInstanceState
返回當(dāng)前頁(yè)
MMKVActivity--->onPause
AddShowHideFragmentInFragmentActivity--->onRestart
AddFragmentInFragment--->onStart
BlankFragment2--->onStart
AddShowHideFragmentInFragmentActivity--->onStart
AddShowHideFragmentInFragmentActivity--->onResume
AddFragmentInFragment--->onResume
BlankFragment2--->onResume <<=================== 當(dāng)前頁(yè)
三、小結(jié)
上面列舉了四種不同的使用場(chǎng)景，以及各種常見(jiàn)的操作邏輯，除了保證頁(yè)面只有顯示為當(dāng)前頁(yè)時(shí)才顯示onResume生命周期函數(shù)外，也通過(guò)saveState方法解決了fragment銷毀后，重疊顯示的UI異常。
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