Fragment管理actionbar的menu——FragmentMenuSupport

/**
* Demonstrates how fragments can participate in the options menu.
*/
public class FragmentMenuSupport extends FragmentActivity {
Fragment mFragment1;
Fragment mFragment2;
CheckBox mCheckBox1;
CheckBox mCheckBox2;

// Update fragment visibility when check boxes are changed.
final OnClickListener mClickListener = new OnClickListener() {
public void onClick(View v) {
updateFragmentVisibility();
}
};

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

// Make sure the two menu fragments are created.
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
mFragment1 = fm.findFragmentByTag("f1");
mFragment2 = fm.findFragmentByTag("f2");
if (mFragment2 == null) {
mFragment2 = new Menu2Fragment();
ft.add(mFragment2, "f2"); //不管是hide 还是show,都不会打破menuiem之间的顺序
//这个顺序是由add的顺序决定的~
}
if (mFragment1 == null) {
mFragment1 = new MenuFragment();
ft.add(mFragment1, "f1");
}
ft.commit();

// Watch check box clicks.
mCheckBox1 = (CheckBox) findViewById(R.id.menu1);
mCheckBox1.setOnClickListener(mClickListener);
mCheckBox2 = (CheckBox) findViewById(R.id.menu2);
mCheckBox2.setOnClickListener(mClickListener);

// Make sure fragments start out with correct visibility.
updateFragmentVisibility();
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// Make sure fragments are updated after check box view state is restored.
updateFragmentVisibility();
}

// Update fragment visibility based on current check box state.
void updateFragmentVisibility() {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
if (mCheckBox2.isChecked()) ft.show(mFragment2);
else ft.hide(mFragment2);
if (mCheckBox1.isChecked()) ft.show(mFragment1);
else ft.hide(mFragment1);
ft.commit();
}

/**
* A fragment that displays a menu.  This fragment happens to not
* have a UI (it does not implement onCreateView), but it could also
* have one if it wanted.
*/
//这是一个没有UIview的fragment,但是依然可以管理actionbar添加每一个fragment想要的menuitem
public static class MenuFragment extends Fragment {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
MenuItem item;
item = menu.add("Menu 1b");
MenuItemCompat.setShowAsAction(item, MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
item = menu.add("Menu 1c");
MenuItemCompat.setShowAsAction(item, MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
}
}

/**
* Second fragment with a menu.
*/
public static class Menu2Fragment extends Fragment {

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setHasOptionsMenu(true);
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
MenuItem item;
item = menu.add("Menu 1a");
MenuItemCompat.setShowAsAction(item, MenuItemCompat.SHOW_AS_ACTION_IF_ROOM);
}
}
}