Android ActionBar使用方法（二）
有关Android活动栏-ActionBar的功能除了添加活动条目 Action Items和添加活动视图 Action View外今天Android123和大家一起来看下支持多Fragment切换的ActionBar标签页和下拉导航。
三、添加标签 Tabs
在ActionBar中实现标签页可以实现android.app.ActionBar.TabListener ，重写onTabSelected、onTabUnselected和onTabReselected方法来关联Fragment。代码如下
private class MyTabListener implements ActionBar.TabListener {
private TabContentFragment mFragment;
// Called to create an instance of the listener when adding a new tab
public TabListener(TabContentFragment fragment) {
mFragment = fragment;
}
@Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
ft.add(R.id.fragment_content, mFragment, null);
}
@Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
ft.remove(mFragment);
}
@Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
// do nothing
}
}
接下来我们创建ActionBar在Activity中，代码如下
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final ActionBar actionBar = getActionBar(); //Android开发网提示getActionBar方法一定在setContentView后面
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
actionBar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
Fragment artistsFragment = new ArtistsFragment();
actionBar.addTab(actionBar.newTab().setText(R.string.tab_artists)
.setTabListener(new TabListener(artistsFragment)));
Fragment albumsFragment = new AlbumsFragment();
actionBar.addTab(actionBar.newTab().setText(R.string.tab_albums)
.setTabListener(new TabListener(albumsFragment)));
}
四、添加下拉导航 Drop-down Navigation
创建一个SpinnerAdapter提供下拉选项，和Tab方式不同的是Drop-down只需要修改下setNavigationMode的模式，将ActionBar.NAVIGATION_MODE_TABS改为ActionBar.NAVIGATION_MODE_LIST，最终改进后的代码为
ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);You should perform this during your activity's onCreate() method.
actionBar.setListNavigationCallbacks(mSpinnerAdapter, mNavigationCallback);
上面我们通过setListNavigationCallbacks方法绑定一个SpinnerAdapter控件，具体的OnNavigationListener代码示例为
mOnNavigationListener = new OnNavigationListener() {
String[] strings = getResources().getStringArray(R.array.action_list);
@Override
public boolean onNavigationItemSelected(int position, long itemId) {
ListContentFragment newFragment = new ListContentFragment();
FragmentTransaction ft = openFragmentTransaction();
ft.replace(R.id.fragment_container, newFragment, strings[position]);
ft.commit();
return true;
}
};
而其中的ListContentFragment的代码为
public class ListContentFragment extends Fragment {
private String mText;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
mText = getTag();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
TextView text = new TextView(getActivity());
text.setText(mText);
return text;
}
}