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;

@Overrideprotected 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;@Overridepublic void onAttach(Activity activity) {super.onAttach(activity);mText = getTag();}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {TextView text = new TextView(getActivity());text.setText(mText);return text;}}