Android ActionBar详解(二)：ActionBar实现Tabs标签以及下拉导航

一.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;
   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) {
 }

}

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(); //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)));
}

二. 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);
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;
}
}