启用下拉导航的基本步骤是：

1.创建一个SpinnerAdapter,它为列表中的每个项目提供下拉列表和可用项目列表.

2.实现ActionBar.OnNavigationListener来定义当用户从列表中选择一个项目时发生的行为.

3.在活动的onCreate()方法中,通过调用setNavigationMode(NAVIGATION_MODE_LIST)来启用操作栏的下拉列表.

4.使用setListNavigationCallbacks()为下拉列表设置回调函数

http://developer.android.com/guide/topics/ui/actionbar.html

检查添加下拉导航的主题

例：

public class MainActivity extends Activity implements OnNavigationListener

然后

getActionBar().setDisplayShowTitleEnabled(false);
    getActionBar().setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
    SpinnerAdapter mSpinnerAdapter = ArrayAdapter.createFromResource(this,R.array.planets_array,android.R.layout.simple_spinner_dropdown_item);

    getActionBar().setListNavigationCallbacks(mSpinnerAdapter,this);

然后

@Override
public boolean onNavigationItemSelected(int arg0,long arg1) {
     Toast.makeText(getApplicationContext()," text",1000).show();
    return true;
}

快照

例：

public class MainActivity extends Activity implements ActionBar.OnNavigationListener {
    private DrawerLayout mDrawerLayout;
    private ListView mDrawerList;
    public ActionBarDrawerToggle mDrawerToggle;

    private CharSequence mDrawerTitle;
    private CharSequence mTitle;
    private String[] mPlanetTitles;
    ActionBar actionBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        actionBar = getActionBar();


        SpinnerAdapter mSpinnerAdapter = ArrayAdapter.createFromResource(this,android.R.layout.simple_spinner_dropdown_item);
        actionBar.setDisplayShowTitleEnabled(false);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
        getActionBar().setListNavigationCallbacks(mSpinnerAdapter,this);

        //mTitle = mDrawerTitle = getTitle();
        mPlanetTitles = getResources().getStringArray(R.array.planets_array);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.left_drawer);

       // mDrawerList.setBackgroundColor(Color.WHITE);
        // set a custom shadow that overlays the main content when the drawer opens
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow,GravityCompat.START);
        // set up the drawer's list view with items and click listener

        mDrawerList.setAdapter(new ArrayAdapter<String>(this,R.layout.drawer_list_item,mPlanetTitles));

        mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

        // enable ActionBar app icon to behave as action to toggle nav drawer
        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);

        // ActionBarDrawerToggle ties together the the proper interactions
        // between the sliding drawer and the action bar app icon
        mDrawerToggle = new ActionBarDrawerToggle(
                this,/* host Activity */
                mDrawerLayout,/* DrawerLayout object */
                R.drawable.ic_drawer,/* nav drawer image to replace 'Up' caret */
                R.string.drawer_open,/* "open drawer" description for accessibility */
                R.string.drawer_close  /* "close drawer" description for accessibility */
                ) {
            public void onDrawerClosed(View view) {
                getActionBar().setTitle(mTitle);
                invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }

            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle(mDrawerTitle);
                invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);

        if (savedInstanceState == null) {
            selectItem(0);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main,menu);
        return super.onCreateOptionsMenu(menu);
    }

    /* Called whenever we call invalidateOptionsMenu() */
    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // If the nav drawer is open,hide action items related to the content view
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
        menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);

        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
         // The action bar home/up action should open or close the drawer.
         // ActionBarDrawerToggle will take care of this.
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        // Handle action buttons
        switch(item.getItemId()) {

        case R.id.action_websearch:
            // create intent to perform web search for this planet
            Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
            intent.putExtra(SearchManager.QUERY,getActionBar().getTitle());
            // catch event that there's no activity to handle intent
            if (intent.resolveActivity(getPackageManager()) != null) {
                startActivity(intent);
            } else {
                Toast.makeText(this,R.string.app_not_available,Toast.LENGTH_LONG).show();
            }
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }

    /* The click listner for ListView in the navigation drawer */
    private class DrawerItemClickListener implements ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent,View view,int position,long id) {
            selectItem(position);
        }
    }

    private void selectItem(int position) {


        ActionBar actionBar =getActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
        Fragment fragment = new PlanetFragment();
        Bundle args = new Bundle();
        args.putInt(PlanetFragment.ARG_PLANET_NUMBER,position);
        fragment.setArguments(args);

        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.content_frame,fragment).commit();

        // update selected item and title,then close the drawer

        mDrawerList.setItemChecked(position,true);
      //  setTitle(mPlanetTitles[position]);
        mDrawerLayout.closeDrawer(mDrawerList);


    }

    @Override
    public void setTitle(CharSequence title) {
        mTitle = title;
        //getActionBar().setTitle(mTitle);
    }

    /**
     * When using the ActionBarDrawerToggle,you must call it during
     * onPostCreate() and onConfigurationChanged()...
     */

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        // Sync the toggle state after onRestoreInstanceState has occurred.
        mDrawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Pass any configuration change to the drawer toggls
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

    /**
     * Fragment that appears in the "content_frame",shows a planet
     */
    public static class PlanetFragment extends Fragment {
        public static final String ARG_PLANET_NUMBER = "planet_number";
        private static WeakReference<MainActivity> mTarget;




        @Override
        public void onActivityCreated(Bundle savedInstanceState) {
            super.onActivityCreated(savedInstanceState);

             if(mTarget!=null)
             {
                 MainActivity target = mTarget.get();
                 ActionBar actionBar = getActivity().getActionBar();
             actionBar.setDisplayHomeAsUpEnabled(true);
             //actionBar.setTitle("Fragment");
            //target.mDrawerToggle.setDrawerIndicatorEnabled(false);
             }
             else
             {
                 Log.i("............","Null");
             }
        }

        @Override
        public void onAttach(Activity activity) {
            // TODO Auto-generated method stub
            super.onAttach(activity);
        }

        @Override
        public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
            mTarget = new WeakReference<MainActivity>( (MainActivity) getActivity());
            View rootView = inflater.inflate(R.layout.fragment_planet,container,false);

            int i = getArguments().getInt(ARG_PLANET_NUMBER);
            String planet = getResources().getStringArray(R.array.planets_array)[i];

            int imageId = getResources().getIdentifier(planet.toLowerCase(Locale.getDefault()),"drawable",getActivity().getPackageName());
            ((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId);
           // getActivity().setTitle(planet);
            return rootView;
        }
    }

    @Override
    public boolean onNavigationItemSelected(int itemPosition,long itemId) {
        // TODO Auto-generated method stub
        Toast.makeText(getApplicationContext(),"text",Toast.LENGTH_LONG).show();
        return true;
    }
}

activity_main.xml中

<android.support.v4.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!-- As the main content view,the view below consumes the entire
         space available using match_parent in both dimensions. -->
    <FrameLayout
        android:id="@+id/content_frame"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <!-- android:layout_gravity="start" tells DrawerLayout to treat
         this as a sliding drawer on the left side for left-to-right
         languages and on the right side for right-to-left languages.
         The drawer is given a fixed width in dp and extends the full height of
         the container. A solid background is used for contrast
         with the content view. -->
    <ListView
        android:id="@+id/left_drawer"
        android:layout_width="240dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:choiceMode="singleChoice"
        android:divider="@android:color/transparent"
        android:dividerHeight="0dp"
        />


</android.support.v4.widget.DrawerLayout>

drawe_list_item.xml

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:background="@drawable/selector"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceListItemSmall"
    android:gravity="center_vertical"
    android:paddingLeft="16dp"
    android:paddingRight="16dp"
    android:textColor="#fff"

    android:minHeight="?android:attr/listPreferredItemHeightSmall"/>

fragment_planet.xml

<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/image"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000"
    android:gravity="center"
    android:padding="32dp" />