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;
}
}

有关Android ActionBar的四种方式我们已经大概了解，具体的示例工程代码，明天Android开发网继续解析

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