处理屏幕方向变化的片段？

我正在使用这种代码来处理主要活动中的三个片段......

FragmentA is Fixed it One Frame .. I change FragmentB and FragmentC on Button Click on FragmentA. his Code is Running well either in Portrait or Landscape view .Here is The Code bellow.

public class MainActivity extends FragmentActivity implements
        OnSwitchClickListener {

    FragmentManager manager;
    FragmentA fragA;
    FragmentB fragB;
    FragmentC fragC;

    boolean fragBSet = false;

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

        fragA = new FragmentA();
        fragB = new FragmentB();
        fragC = new FragmentC();

        manager = getSupportFragmentManager();
        FragmentTransaction ft = manager.beginTransaction();

        ft.add(R.id.a_container, fragA, "frag A");

        if (fragBSet) {
            ft.add(R.id.bc_container, fragC, "frag C");
        } else {
            ft.add(R.id.bc_container, fragB, "frag B");
        }
        fragBSet = true;
        ft.commit();

    }

    @Override
    public void onSwitchClick(View v) {
        Toast.makeText(getApplicationContext(), "Switch clkick from Activity",
                Toast.LENGTH_LONG).show();
        FragmentTransaction ft = manager.beginTransaction();
        if (fragBSet) {
            ft.remove(fragB);
            ft.add(R.id.bc_container, fragC, "frag C");
            fragBSet = false;
        } else {
            ft.remove(fragC);
            ft.add(R.id.bc_container, fragB, "frag B");
            fragBSet = true;
        }

        ft.commit();

    }

这段代码在纵向或横向视图中都运行良好......但是每当我更改方向时，两个片段都会相互覆盖。

需要解决方案。

当你的方向改变时，你的Activity被重新创建。

"In the scenario where a user rotates their device, Android will destroy your 
application’s activity(s).  Before destroying them it calls, onSaveInstanceState,
allowing developers to persist data.  Once the activity is recreated post 
rotation, the OS will call onRestoreInstanceState giving developers a chance to 
restore the application state pre-rotation."  

你应该尽力挽救你的Fragments State.

放置片段: 将对片段的引用放入 Bundle 中。该 Bundle 可以持久保存为已保存状态，并且稍后恢复 getFragment(Bundle, String) 时将返回同一片段的当前实例。

@Override
protected void onSaveInstanceState(Bundle outState) {
   FragmentManager manager = getFragmentManager();
   manager.putFragment(outState, MyFragment.TAG, mMyFragment);
}  

获取片段: 检索先前使用 putFragment(Bundle, String, Fr​​agment) 放置的引用的当前 Fragment 实例。

private void instantiateFragments(Bundle inState) {
   FragmentManager manager = getFragmentManager();
   FragmentTransaction transaction = manager.beginTransaction();

   if (inState != null) {
      mMyFragment = (MyFragment) manager.getFragment(inState, MyFragment.TAG);
   } else {
      mMyFragment = new MyFragment();
      transaction.add(R.id.fragment, mMyFragment, MyFragment.TAG);
      transaction.commit();
   }
}  

恢复片段:

@Override
protected void onRestoreInstanceState(Bundle inState) {
   instantiateFragments(inState);
}  

希望这可以帮助。