详解Android ActionBar之二：ActionBar添加Tabs标签和下拉导航

本节主要讲解ActionBar如何添加Tabs标签和下拉导航。

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：

Java代码

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：

Java代码

@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：

Java代码

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：

Java代码

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：

Java代码

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;

}

}