Fragment恢复,保存状态

• fragment在onCreate中设置setRetainInstance(true);
• 如果涉及到保存数据,在onSaveInstanceState保存数据
• 在onCreateView获取bundle

MyFragment
在onCreateView,onCreate,onActivityCreate均可获得bundle
注意: Fragment没有onRestoreInstance方法

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_my, container, fals
    mTextView = (TextView) view.findViewById(R.id.tv);
    //!!!!!!获取时间
    if (savedInstanceState == null) {
        time = System.currentTimeMillis() + "";
    } else {
        time = savedInstanceState.getString("time");
    }
    mTextView.setText(time);
    return view;
}
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //!!!!!!!保存Instance
    setRetainInstance(true);
}
@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    //!!!!!!!时间保存
    outState.putString("time", time);
}

MainActivity
通过tag找到对应的fragment

public class MainActivity extends AppCompatActivity {
    private MyFragment myFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        FragmentManager fragmentManager = getSupportFragmentManager();
        myFragment = (MyFragment) fragmentManager.findFragmentByTag("myFragment");
        if (myFragment == null) {
            myFragment = new MyFragment();
            fragmentManager.beginTransaction().replace(R.id.fragment_fl, myFragment, "myFragment").commit();
        }
    }
}

layout.activity_main

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.zhang.fragmentsave.MainActivity">

    <FrameLayout
        android:id="@+id/fragment_fl"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
</RelativeLayout>