ViewPager 在方向更改时崩溃 - 碎片堆积并导致 OutOfMemoryException
ViewPager crashes on orientation change - fragments stack up and cause OutOfMemoryException
我的项目结构如下所示:
MainActivity->PagerFragment->PagerViewAdapter 持有多个 PagerImageFragments
我在几次方向更改后收到 OutOfMemoryException,但寻呼机显示位图 "efficiently"(我使用 AsyncTask/LruCache)。然后我注意到应用程序使用的内存在每次方向更改后都会成倍增加,并且从日志中我可以看到 PagerFragment 中的 onCreate() 每次被调用两次。我认为因为我的片段被重新创建和堆叠,导致了这个问题。我该如何阻止这种情况发生?
我试过设置
@Override
protected void onSaveInstanceState(final Bundle outState) {
// super.onSaveInstanceState(outState);
}
这对我没有任何帮助。然后我试了:
setRetainInstance(true);
这让我的 PagerFragment 只重新创建了一次,但这仍然不是我想要的。
编辑:我对 MainActivity 做了一些改动,所以它只在没有保存实例的情况下进行初始化,并在启动新实例时删除所有片段。我删除了 setRetainInstance(true)。我现在可以多次更改方向(它仍然会以 OOM 异常结束,但触发它需要更长的时间)。但现在还有另一个问题 - 如果我将 PagerFragment 留给另一个片段并返回它会崩溃。
主要活动:
public class MainActivity extends AppCompatActivity {
private final String TAG = "LOG";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState==null) {
...
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
PagerFragment fragment = new PagerFragment();
fragmentTransaction.add(R.id.fragment_container, fragment);
fragmentTransaction.commit();
...
switchContent(new PagerFragment());
}
}
public void switchContent(Fragment fragment) {
FragmentManager fm = getSupportFragmentManager();
List<Fragment> fragmentList = fm.getFragments();
if (fragmentList != null) {
for (Fragment frag : fragmentList ) {
Log.d(TAG, "switchContent: destroying "+frag);
fm.beginTransaction()
.remove(frag).commit();
}
}
fm.beginTransaction()
.replace(R.id.fragment_container, fragment)
.commit();
}
PagerFragment 内部:
PagerAdapter adapter = new PagerViewAdapter(getFragmentManager(), pdfFactory.getPageCount());
ViewPager pager = (ViewPager) getActivity().findViewById(R.id.pager);
pager.setAdapter(adapter);
pager.setPageMargin((int) getResources().getDimension(R.dimen.activity_horizontal_margin));
pager.setCurrentItem(position);
pager.setOffscreenPageLimit(2);
PagerViewAdapter:
public class PagerViewAdapter extends FragmentStatePagerAdapter {
private final int size;
public PagerViewAdapter(FragmentManager fm, int size) {
super(fm);
this.size = size;
}
@Override
public int getCount() {
return size;
}
@Override
public Fragment getItem(int position) {
return PagerImageFragment.newInstance(position);
}
}
PagerImageFragment:
public class PagerImageFragment extends Fragment {
private PhotoView photoView;
int position;
private MyCache<Integer, Bitmap> myCache;
public static PagerImageFragment newInstance(Integer pos) {
final PagerImageFragment f = new PagerImageFragment();
final Bundle args = new Bundle();
args.putInt("position", pos);
f.setArguments(args);
Log.d("DISPLAY", "Bundling...");
return f;
}
public PagerImageFragment() {}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Initialize the cache
myCache = new MyCache<>( 5 * 1024 * 1024 );
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate and locate the main ImageView
final View v = inflater.inflate(R.layout.pager_element, container, false);
photoView = (PhotoView) v.findViewById(R.id.pager_image);
Bitmap image = myCache.get(position);
if (image != null) {
photoView.setImageBitmap(image);
}
else {
new SetImageTask(photoView, myCache).execute(position);
}
return v;
}
异常(编辑后):
java.lang.NullPointerException: Attempt to write to field 'int android.support.v4.app.Fragment.mNextAnim' on a null object reference
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:770)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1677)
at android.support.v4.app.FragmentManagerImpl.run(FragmentManager.java:536)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:155)
at android.app.ActivityThread.main(ActivityThread.java:5696)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)
将此添加到清单中的 activity
android:configChanges="orientation|keyboardHidden|screenSize"
<activity android:name="MainActivity"
android:configChanges="orientation|keyboardHidden|screenSize">
</activity>
onConfigurationChanged 将在方向更改时调用,但您的 activity 不会被重新创建,而是 onConfigurationChanged 将被调用并且你必须管理方向变化 如果有 。因此它可以防止 OutOfMemoryException 由于在方向更改时重新创建所有内容而导致的问题。
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Handle orientation changes here
}
首先,您不应将 getFragmentManager 用于您的寻呼机适配器。取而代之的是,使用 getChildFragmentManager
PagerAdapter adapter = new PagerViewAdapter(getChildFragmentManager(), pdfFactory.getPageCount());
如果没有帮助,请将 Leak Canary 库添加到 build.gradle 依赖项以检测内存泄漏 https://github.com/square/leakcanary
事实证明这是 FragmentStateViewPager 中的错误 - 它不会删除视图。解决方法是改用它,虽然不完美但我能找到的最好的东西 https://github.com/adamsp/FragmentStatePagerIssueExample/blob/master/app/src/main/java/com/example/fragmentstatepagerissueexample/app/FixedFragmentStatePagerAdapter.java
我的项目结构如下所示:
MainActivity->PagerFragment->PagerViewAdapter 持有多个 PagerImageFragments
我在几次方向更改后收到 OutOfMemoryException,但寻呼机显示位图 "efficiently"(我使用 AsyncTask/LruCache)。然后我注意到应用程序使用的内存在每次方向更改后都会成倍增加,并且从日志中我可以看到 PagerFragment 中的 onCreate() 每次被调用两次。我认为因为我的片段被重新创建和堆叠,导致了这个问题。我该如何阻止这种情况发生?
我试过设置
@Override
protected void onSaveInstanceState(final Bundle outState) {
// super.onSaveInstanceState(outState);
}
这对我没有任何帮助。然后我试了:
setRetainInstance(true);
这让我的 PagerFragment 只重新创建了一次,但这仍然不是我想要的。
编辑:我对 MainActivity 做了一些改动,所以它只在没有保存实例的情况下进行初始化,并在启动新实例时删除所有片段。我删除了 setRetainInstance(true)。我现在可以多次更改方向(它仍然会以 OOM 异常结束,但触发它需要更长的时间)。但现在还有另一个问题 - 如果我将 PagerFragment 留给另一个片段并返回它会崩溃。
主要活动:
public class MainActivity extends AppCompatActivity {
private final String TAG = "LOG";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState==null) {
...
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
PagerFragment fragment = new PagerFragment();
fragmentTransaction.add(R.id.fragment_container, fragment);
fragmentTransaction.commit();
...
switchContent(new PagerFragment());
}
}
public void switchContent(Fragment fragment) {
FragmentManager fm = getSupportFragmentManager();
List<Fragment> fragmentList = fm.getFragments();
if (fragmentList != null) {
for (Fragment frag : fragmentList ) {
Log.d(TAG, "switchContent: destroying "+frag);
fm.beginTransaction()
.remove(frag).commit();
}
}
fm.beginTransaction()
.replace(R.id.fragment_container, fragment)
.commit();
}
PagerFragment 内部:
PagerAdapter adapter = new PagerViewAdapter(getFragmentManager(), pdfFactory.getPageCount());
ViewPager pager = (ViewPager) getActivity().findViewById(R.id.pager);
pager.setAdapter(adapter);
pager.setPageMargin((int) getResources().getDimension(R.dimen.activity_horizontal_margin));
pager.setCurrentItem(position);
pager.setOffscreenPageLimit(2);
PagerViewAdapter:
public class PagerViewAdapter extends FragmentStatePagerAdapter {
private final int size;
public PagerViewAdapter(FragmentManager fm, int size) {
super(fm);
this.size = size;
}
@Override
public int getCount() {
return size;
}
@Override
public Fragment getItem(int position) {
return PagerImageFragment.newInstance(position);
}
}
PagerImageFragment:
public class PagerImageFragment extends Fragment {
private PhotoView photoView;
int position;
private MyCache<Integer, Bitmap> myCache;
public static PagerImageFragment newInstance(Integer pos) {
final PagerImageFragment f = new PagerImageFragment();
final Bundle args = new Bundle();
args.putInt("position", pos);
f.setArguments(args);
Log.d("DISPLAY", "Bundling...");
return f;
}
public PagerImageFragment() {}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Initialize the cache
myCache = new MyCache<>( 5 * 1024 * 1024 );
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate and locate the main ImageView
final View v = inflater.inflate(R.layout.pager_element, container, false);
photoView = (PhotoView) v.findViewById(R.id.pager_image);
Bitmap image = myCache.get(position);
if (image != null) {
photoView.setImageBitmap(image);
}
else {
new SetImageTask(photoView, myCache).execute(position);
}
return v;
}
异常(编辑后):
java.lang.NullPointerException: Attempt to write to field 'int android.support.v4.app.Fragment.mNextAnim' on a null object reference
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:770)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1677)
at android.support.v4.app.FragmentManagerImpl.run(FragmentManager.java:536)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:155)
at android.app.ActivityThread.main(ActivityThread.java:5696)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1028)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:823)
将此添加到清单中的 activity
android:configChanges="orientation|keyboardHidden|screenSize"
<activity android:name="MainActivity"
android:configChanges="orientation|keyboardHidden|screenSize">
</activity>
onConfigurationChanged 将在方向更改时调用,但您的 activity 不会被重新创建,而是 onConfigurationChanged 将被调用并且你必须管理方向变化 如果有 。因此它可以防止 OutOfMemoryException 由于在方向更改时重新创建所有内容而导致的问题。
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// Handle orientation changes here
}
首先,您不应将 getFragmentManager 用于您的寻呼机适配器。取而代之的是,使用 getChildFragmentManager
PagerAdapter adapter = new PagerViewAdapter(getChildFragmentManager(), pdfFactory.getPageCount());
如果没有帮助,请将 Leak Canary 库添加到 build.gradle 依赖项以检测内存泄漏 https://github.com/square/leakcanary
事实证明这是 FragmentStateViewPager 中的错误 - 它不会删除视图。解决方法是改用它,虽然不完美但我能找到的最好的东西 https://github.com/adamsp/FragmentStatePagerIssueExample/blob/master/app/src/main/java/com/example/fragmentstatepagerissueexample/app/FixedFragmentStatePagerAdapter.java