问带ActionBar的双片段旋转安卓系统

EN

public void onTabSelected(Tab tab, FragmentTransaction ft) {
        // previous Fragment management
        Fragment prevFragment;
        FragmentManager fm = mActivity.getFragmentManager();
        prevFragment = fm.findFragmentByTag(mTag); 
        if (prevFragment != null) { 
            mFragment = prevFragment; 
        } // \previous Fragment management

        // Check if the fragment is already initialized
        if (mFragment == null) {
            // If not, instantiate and add it to the activity
            mFragment = Fragment.instantiate(mActivity, mClass.getName());
            ft.add(android.R.id.content, mFragment, mTag);
        } else {
            // If it exists, simply attach it in order to show it
            ft.attach(mFragment);
        }
    }

   @Override
   public void onCreate (final android.os.Bundle savedInstanceState)
   {
      if (savedInstanceState != null)
      {
         savedInstanceState.remove ("android:support:fragments");
      } // if

      super.onCreate (savedInstanceState);
…
      return;
   } // onCreate

public class TabHostActivity extends SherlockFragmentActivity {

   private static final String SELETED_TAB_INDEX = "tabIndex";


   @Override
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);

     // Setup the action bar
     ActionBar actionBar = getSupportActionBar();
     actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

     // Create the Tabs you need and add them to the actionBar...

     if (savedInstanceState != null) {
        // Select the tab that was selected before orientation change
        int index = savedInstanceState.getInt(SELETED_TAB_INDEX);
        actionBar.setSelectedNavigationItem(index);
     }
   }

   @Override
   protected void onSaveInstanceState(Bundle outState) {
     super.onSaveInstanceState(outState);
     // Save the index of the currently selected tab 
     outState.putInt(SELETED_TAB_INDEX, getSupportActionBar().getSelectedTab().getPosition());
   }
}

  private class MyTabsListener<T extends Fragment> implements ActionBar.TabListener {
     private Fragment fragment;
     private final SherlockFragmentActivity host;
     private final Class<Fragment> type;
     private String tag;

     public MyTabsListener(SherlockFragmentActivity parent, String tag, Class type) {
        this.host = parent;
        this.tag = tag;
        this.type = type;
     }

     @Override
     public void onTabSelected(Tab tab, FragmentTransaction transaction) {
        /*
         * The fragment which has been added to this listener may have been
         * replaced (can be the case for lists when drilling down), but if the
         * tag has been retained, we should find the actual fragment that was
         * showing in this tab before the user switched to another.
         */
        Fragment currentlyShowing = host.getSupportFragmentManager().findFragmentByTag(tag);

        // Check if the fragment is already initialised
        if (currentlyShowing == null) {
          // If not, instantiate and add it to the activity
          fragment = SherlockFragment.instantiate(host, type.getName());
          transaction.add(android.R.id.content, fragment, tag);
        } else {
          // If it exists, simply attach it in order to show it
          transaction.attach(currentlyShowing);
        }
     }

     public void onTabUnselected(Tab tab, FragmentTransaction fragmentTransaction) {
        /*
         * The fragment which has been added to this listener may have been
         * replaced (can be the case for lists when drilling down), but if the
         * tag has been retained, we should find the actual fragment that's
         * currently active.
         */
        Fragment currentlyShowing = host.getSupportFragmentManager().findFragmentByTag(tag);
        if (currentlyShowing != null) {
          // Detach the fragment, another tab has been selected
          fragmentTransaction.detach(currentlyShowing);
        } else if (this.fragment != null) {
          fragmentTransaction.detach(fragment);
        }
     }

     public void onTabReselected(Tab tab, FragmentTransaction fragmentTransaction) {
        // This tab is already selected
     }