源代码解说ActionBar的各种使用方法

1. Navigation Drawer

很多应用程序都使用了Navigation Drawer，如网易邮箱client。该控件位于 android.support.v4.widget.DrawerLayout ，使用方法例如以下，点击下载源代码：

<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">
    <!-- The main content view -->
    <FrameLayout
        android:id="@+id/content_frame"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    <!-- The navigation drawer -->
     <!-- should not be larger than 320 to show content -->
    <ListView android:id="@+id/left_drawer"
        android:layout_width="180dp"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:choiceMode="singleChoice"
        android:divider="@android:color/transparent"
        android:dividerHeight="0dp"
        android:background="#111"/>
</android.support.v4.widget.DrawerLayout> 

在编写代码之前确保增加了support v4库。
创建一个布局文件 fragment_layout来被一个Fragment显示

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:text="Placeholder Text"
        android:layout_gravity="center"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</LinearLayout> 

创建OpertingSystemFragment类

package com.vogella.android.actionbar.navigationdrawer;

import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class OpertingSystemFragment extends Fragment {
  public static final String ARG_OS= "OS";
  private String string;
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
      Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_layout, null);
    TextView textView = (TextView) view.findViewById(R.id.textView1);
    textView.setText(string);
    return view;
  }
  @Override
  public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);  
  }
  @Override
  public void setArguments(Bundle args) {
    string = args.getString(ARG_OS);
  }
} 

加入String

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">Navigationdrawer</string>
    <string name="action_settings">Settings</string>
    <string name="action_update">Update</string>
    <string name="drawer_open">Open Drawer</string>
    <string name="drawer_close">Close Drawer</string>
    <string name="hello_world">Hello world!</string>
    <string-array name="operating_systems">
        <item >Android</item>
        <item >iPhone</item>
        <item >Windows Mobile</item>
    </string-array>

</resources> 

最后，创建Activity

package com.vogella.android.actionbar.navigationdrawer;

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.widget.DrawerLayout;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends Activity {
    private String[] mPlanetTitles;
    private DrawerLayout mDrawerLayout;
    private ListView mDrawerList;
  private ActionBarDrawerToggle mDrawerToggle;
  private CharSequence title;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        title = getActionBar().getTitle();
        mPlanetTitles = getResources().getStringArray(R.array.operating_systems);
        System.out.println(mPlanetTitles.length);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.left_drawer);

        // Set the adapter for the list view
        mDrawerList.setAdapter(new ArrayAdapter<String>(this,
                R.layout.drawer_item,R.id.content, mPlanetTitles));
        // Set the list's click listener
        mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
        
        mDrawerToggle = new ActionBarDrawerToggle(this,                  /* host Activity */
                mDrawerLayout,         /* DrawerLayout object */
                R.drawable.ic_drawer,  /* nav drawer icon to replace 'Up' caret */
                R.string.drawer_open,  /* "open drawer" description */
                R.string.drawer_close  /* "close drawer" description */) {

            
/** Called when a drawer has settled in a completely closed state. */

            public void onDrawerClosed(View view) {
                getActionBar().setTitle(title);
            }

            
/** Called when a drawer has settled in a completely open state. */

            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle("Open Drawer");
            }
        };

        // Set the drawer toggle as the DrawerListener
        mDrawerLayout.setDrawerListener(mDrawerToggle);

        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);
        

    }
    
    private class DrawerItemClickListener implements ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView parent, View view, int position, long id) {
            selectItem(position);
        }
    }
    
    @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);
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
      getMenuInflater().inflate(R.menu.main, menu);
      return super.onCreateOptionsMenu(menu);
    }
    
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Pass the event to ActionBarDrawerToggle, if it returns
        // true, then it has handled the app icon touch event
        if (mDrawerToggle.onOptionsItemSelected(item)) {
          return true;
        }
        // Handle your other action bar items...
        switch (item.getItemId()) {
    case R.id.action_settings:
      Toast.makeText(this, "Settings selected", Toast.LENGTH_LONG).show();
      break;

    default:
      break;
    }
        return super.onOptionsItemSelected(item);
    }


    
/** Swaps fragments in the main content view */

    private void selectItem(int position) {
        // create a new fragment and specify the planet to show based on position
        Fragment fragment = new OpertingSystemFragment();
        Bundle args = new Bundle();
        args.putInt(OpertingSystemFragment.ARG_OS, position);
        fragment.setArguments(args);

        // Insert the fragment by replacing any existing fragment
        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction()
                       .replace(R.id.content_frame, fragment)
                       .commit();

        // Highlight the selected item, update the title, and close the drawer
        mDrawerList.setItemChecked(position, true);
        getActionBar().setTitle((mPlanetTitles[position]));
        mDrawerLayout.closeDrawer(mDrawerList);
    }

  
} 

2. ActionBar + Tab navigation + Fragment
Fragment能够用来和action bar一起使用来实现导航。以下的代码将介绍使用方法，点击下载源代码。

ackage com.vogella.android.actionbar.tabs;

import android.app.ActionBar;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class MainActivity extends FragmentActivity implements
    ActionBar.TabListener {

 
/** * The serialization (saved instance state) Bundle key representing the * current tab position. */

  private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item";

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

    // Set up the action bar to show tabs.
    final ActionBar actionBar = getActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // for each of the sections in the app, add a tab to the action bar.
    actionBar.addTab(actionBar.newTab().setText(R.string.title_section1)
        .setTabListener(this));
    actionBar.addTab(actionBar.newTab().setText(R.string.title_section2)
        .setTabListener(this));
    actionBar.addTab(actionBar.newTab().setText(R.string.title_section3)
        .setTabListener(this));
  }

  @Override
  public void onRestoreInstanceState(Bundle savedInstanceState) {
    // Restore the previously serialized current tab position.
    if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) {
      getActionBar().setSelectedNavigationItem(savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
    }
  }

  @Override
  public void onSaveInstanceState(Bundle outState) {
    // Serialize the current tab position.
    outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getActionBar()
        .getSelectedNavigationIndex());
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
  }

  @Override
  public void onTabSelected(ActionBar.Tab tab,
      FragmentTransaction fragmentTransaction) {
    // When the given tab is selected, show the tab contents in the
    // container view.
    Fragment fragment = new DummySectionFragment();
    Bundle args = new Bundle();
    args.putInt(DummySectionFragment.ARG_SECTION_NUMBER,
        tab.getPosition() + 1);
    fragment.setArguments(args);
    getFragmentManager().beginTransaction()
        .replace(R.id.container, fragment).commit();
  }

  @Override
  public void onTabUnselected(ActionBar.Tab tab,
      FragmentTransaction fragmentTransaction) {
  }

  @Override
  public void onTabReselected(ActionBar.Tab tab,
      FragmentTransaction fragmentTransaction) {
  }

 
/** * A dummy fragment representing a section of the app */

  public static class DummySectionFragment extends Fragment {
    public static final String ARG_SECTION_NUMBER = "placeholder_text";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
      TextView textView = new TextView(getActivity());
      textView.setGravity(Gravity.CENTER);
      textView.setText(Integer.toString(getArguments().getInt(ARG_SECTION_NUMBER)));
      return textView;
    }
  }

} 

3.Dropdown menu 导航
Dropdown菜单也常被用在ActionBar中，以下的代码介绍了使用方法，完整代码点击下载：

package com.vogella.android.actionbar.spinner;

import android.app.ActionBar;
import android.app.Fragment;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

public class MainActivity extends FragmentActivity implements
    ActionBar.OnNavigationListener {

  
/** * The serialization (saved instance state) Bundle key representing the * current dropdown position. */

  private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item";

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

    // Set up the action bar to show a dropdown list.
    final ActionBar actionBar = getActionBar();
    actionBar.setDisplayShowTitleEnabled(false);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);

    final String[] dropdownValues = getResources().getStringArray(R.array.dropdown);

    // Specify a SpinnerAdapter to populate the dropdown list.
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(actionBar.getThemedContext(),
        android.R.layout.simple_spinner_item, android.R.id.text1,
        dropdownValues);

    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

    // Set up the dropdown list navigation in the action bar.
    actionBar.setListNavigationCallbacks(adapter, this);

    // use getActionBar().getThemedContext() to ensure
    // that the text color is always appropriate for the action bar
    // background rather than the activity background.
  }

  @Override
  public void onRestoreInstanceState(Bundle savedInstanceState) {
    // Restore the previously serialized current dropdown position.
    if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) {
      getActionBar().setSelectedNavigationItem(savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM));
    }
  }

  @Override
  public void onSaveInstanceState(Bundle outState) {
    // Serialize the current dropdown position.
    outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getActionBar()
        .getSelectedNavigationIndex());
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
  }

  @Override
  public boolean onNavigationItemSelected(int position, long id) {
    // When the given dropdown item is selected, show its contents in the
    // container view.
    Fragment fragment = new DummySectionFragment();
    Bundle args = new Bundle();
    args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
    fragment.setArguments(args);
    getFragmentManager().beginTransaction()
        .replace(R.id.container, fragment).commit();
    return true;
  }

  
/** * A dummy fragment */

  public static class DummySectionFragment extends Fragment {

    public static final String ARG_SECTION_NUMBER = "placeholder_text";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
      TextView textView = new TextView(getActivity());
      textView.setGravity(Gravity.CENTER);
      textView.setText(Integer.toString(getArguments().getInt(ARG_SECTION_NUMBER)));
      return textView;
    }
  }
} 

截图例如以下：

4. 使用Contextual action 模式

Contextual action mode能够用来在程序执行时切换ActionBar的布局，以下将介绍怎样使用，完整源代码点击下载：
创建布局文件 main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/myView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" >

        <requestFocus />
    </EditText>

</LinearLayout>

创建一个menu XML资源文件 contetual.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <item
        android:id="@+id/toast"
        android:title="Toast">
    </item>

</menu> 

Activity中的带代码例如以下：

package de.vogella.android.socialapp;

import android.app.Activity;
import android.os.Bundle;
import android.view.ActionMode;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.Toast;

public class OverviewActivity extends Activity {
  protected Object mActionMode;
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    // define the contextual action mode
    View view = findViewById(R.id.myView);
    view.setOnLongClickListener(new View.OnLongClickListener() {
      // called when the user long-clicks on someView
      public boolean onLongClick(View view) {
        if (mActionMode != null) {
          return false;
        }

        // start the CAB using the ActionMode.Callback defined above
        mActionMode = OverviewActivity.this
            .startActionMode(mActionModeCallback);
        view.setSelected(true);
        return true;
      }
    });
  }

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

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    Toast.makeText(this, "Just a test", Toast.LENGTH_SHORT).show();
    return true;
  }

  private ActionMode.Callback mActionModeCallback = new ActionMode.Callback() {

    // Called when the action mode is created; startActionMode() was called
    public boolean onCreateActionMode(ActionMode mode, Menu menu) {
      // inflate a menu resource providing context menu items
      MenuInflater inflater = mode.getMenuInflater();
      // assumes that you have "contexual.xml" menu resources
      inflater.inflate(R.menu.contextual, menu);
      return true;
    }

    // called each time the action mode is shown. Always called after
    // onCreateActionMode, but
    // may be called multiple times if the mode is invalidated.
    public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
      return false; // Return false if nothing is done
    }

    // called when the user selects a contextual menu item
    public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
      switch (item.getItemId()) {
      case R.id.toast:
        Toast.makeText(OverviewActivity.this, "Selected menu",
            Toast.LENGTH_LONG).show();
        mode.finish(); // Action picked, so close the CAB
        return true;
      default:
        return false;
      }
    }

    // called when the user exits the action mode
    public void onDestroyActionMode(ActionMode mode) {
      mActionMode = null;
    }
  };

} 

本文參考了这篇文章：

Using the Android action bar (ActionBar) - Tutorial

这篇blog对ActionBar也进行了具体的介绍：
Android ActionBar全然解析，使用官方推荐的最佳导航栏(上)
当然，Android Developer也介绍的非常好：http://developer.android.com/guide/topics/ui/actionbar.html