我正在使用以下代码将 fragment 插入到 Activity 中:

public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    FragmentManager fm = getFragmentManager();
    String tag = "simple";

    Fragment fr = fm.findFragmentByTag(tag);
    if (fr == null)
    {
        SimpleFragment simpleFragment = new SimpleFragment(); 
        FragmentTransaction transaction = fm.beginTransaction();
        transaction.setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out,
                                        android.R.animator.fade_in, android.R.animator.fade_out);
        transaction.add(R.id.main_layout, simpleFragment, tag);
        transaction.addToBackStack(tag);
        transaction.commit();
    }
}

fragment 代码为:

public class SimpleFragment extends ListFragment 
{
    @Override
    public void onActivityCreated(Bundle savedInstanceState) 
    {
        super.onActivityCreated(savedInstanceState);
        getView().setBackgroundColor(Color.YELLOW);
    }
}

当我在启动后通过返回按钮从后台弹出 fragment 时，一切都很好，我可以看到淡出动画。但是，如果我旋转设备并按下后退按钮，那么 fragment 就会消失而没有动画。

这是 Android 行为还是我做错了什么？

编辑: 旋转后 FragmentManager 似乎没有为 BackStackEntry 恢复动画(enterAnim、exitAnim、popEnterAnim 和 popExitAnim)。

FragmentManager 转储(无旋转):

Active Fragments in 4087d668:
  #0: SimpleFragment{408883b0 #0 id=0x7f050000 simple}
    mFragmentId=#7f050000 mContainerId#=7f050000 mTag=simple
    mState=4 mIndex=0 mWho=android:fragment:0 mBackStackNesting=1
    mAdded=true mRemoving=false mResumed=true mFromLayout=false mInLayout=false
    mHidden=false mDetached=false mRetainInstance=false mRetaining=false mHasMenu=false
    mFragmentManager=FragmentManager{4087d668 in ListViewFragmentsActivity{4087d588}}
    mImmediateActivity=my.app.ListViewFragmentsActivity@4087d588
    mActivity=my.app.ListViewFragmentsActivity@4087d588
    mNextAnim=17498112
    mContainer=android.widget.RelativeLayout@408876d8
    mView=android.widget.FrameLayout@40888a70
Added Fragments:
  #0: SimpleFragment{408883b0 #0 id=0x7f050000 simple}
Back Stack:
  #0: android.app.BackStackRecord@408884b8
    mName=simple mIndex=0 mCommitted=true
    mEnterAnim=#10b0000 mExitAnim=#10b0001
    Operations:
      Op #0:
        cmd=1 fragment=SimpleFragment{408883b0 #0 id=0x7f050000 simple}
    enterAnim=17498112 exitAnim=17498113
    popEnterAnim=17498112 popExitAnim=17498113
Back Stack Indices:
  #0: android.app.BackStackRecord@408884b8
FragmentManager misc state:
  mCurState=5 mStateSaved=false mDestroyed=false

FragmentManager 转储(旋转后):

Active Fragments in 40877f38:
  #0: SimpleFragment{40878858 #0 id=0x7f050000 simple}
    mFragmentId=#7f050000 mContainerId#=7f050000 mTag=simple
    mState=4 mIndex=0 mWho=android:fragment:0 mBackStackNesting=1
    mAdded=true mRemoving=false mResumed=true mFromLayout=false mInLayout=false
    mHidden=false mDetached=false mRetainInstance=false mRetaining=false mHasMenu=false
    mFragmentManager=FragmentManager{40877f38 in ListViewFragmentsActivity{40877e58}}
    mImmediateActivity=my.app.ListViewFragmentsActivity@40877e58
    mActivity=my.app.ListViewFragmentsActivity@40877e58
    mContainer=android.widget.RelativeLayout@4087ed50
    mView=android.widget.FrameLayout@4087fc00
Added Fragments:
  #0: SimpleFragment{40878858 #0 id=0x7f050000 simple}
Back Stack:
  #0: android.app.BackStackRecord@40878a78
    mName=simple mIndex=0 mCommitted=false
    Operations:
      Op #0:
        cmd=1 fragment=SimpleFragment{40878858 #0 id=0x7f050000 simple}
Back Stack Indices:
  #0: android.app.BackStackRecord@40878a78
FragmentManager misc state:
  mCurState=5 mStateSaved=false mDestroyed=false

最佳答案

作为一种解决方法，您可以在 fragment 中使用 onCreateAnimator/onCreateAnimation 方法。

例如对于原生 fragment 实现:

@Override
public Animator onCreateAnimator(int transit, boolean enter, int nextAnim) {
    if (enter) {
        return AnimatorInflater.loadAnimator(getActivity(), R.animator.slide_in_top);
    } else {
        return AnimatorInflater.loadAnimator(getActivity(), R.animator.fade_out);
    }
}

使用动画来支持库 fragment 的技术相同。在这种情况下，您还可以根据 fragment 状态和/或参数更好地控制播放动画的方式。

关于android - 配置更改后 fragment 丢失过渡动画，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8837408/