Android 4 学习(20):ActionBar

参考《Pro Android 4.0

ActionBar

11.0之后,ActionBarActivity中默认存在,可以在代码中设置其显示与否:

 

ActionBar actionBar = getActionBar(); 
// Hide the Action Bar actionBar.hide(); 
// Show the Action Bar actionBar.show(); 

 

也可以在Manifest中设置是否显示ActionBar

 

<activity  android:name=”.MyNonActionBarActivity” android:theme=”@android:style/Theme.Holo.NoActionBar”> 

 

创建一个不显示ActionBarTheme

 

<?xml version=”1.0” encoding=”utf-8”?> 
<resources>   <style name=”NoActionBar” parent=”@style/ActivityTheme”>
    <item name=”android:windowActionBar”>false</item>   </style>
</resources>

 

ActionBar的其他设置:

 

ActionBar actionBar = getActionBar(); 
actionBar.setDisplayShowTitleEnabled(false); 
actionBar.setDisplayUseLogoEnabled(displayLogo);
actionBar.setDisplayShowHomeEnabled(false); 
actionBar.setSubtitle(“Inbox”); 
actionBar.setTitle(“Label:important”);
Resources r = getResources();Drawable myDrawable = r.getDrawable(R.drawable.gradient_header); actionBar.setBackgroundDrawable(myDrawable); 
//ActionBar float above content
@Override
public void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   getWindow().requestFeature(Window.FEATURE_ACTION_BAR_OVERLAY);   setContentView(R.layout.main); }

 

使用ActionBar做导航

新建一个Tab:

Tab tabOne = actionBar.newTab(); 
tabOne.setText(“First Tab”).setIcon(R.drawable.ic_launcher).setContentDescription(“Tab the First”).setTabListener( 
  new TabListener<MyFragment>(this, R.id.fragmentContainer, MyFragment.class)); 
actionBar.addTab(tabOne); 

实现TabListener接口:

 

public static class TabListener<T extends Fragment>  implements ActionBar.TabListener { 
  private MyFragment fragment; 
  private Activity activity; 
  private Class<T> fragmentClass;
  private int fragmentContainer;
  public TabListener(Activity activity, int fragmentContainer, Class<T> fragmentClass) {     this.activity = activity;
    this.fragmentContainer = fragmentContainer;
    this.fragmentClass = fragmentClass;   }   // Called when a new tab has been selected
public void onTabSelected(Tab tab, FragmentTransaction ft) {
  if (fragment == null) {
    String fragmentName = fragmentClass.getName();
    fragment = (MyFragment)Fragment.instantiate(activity, fragmentName);
    ft.add(fragmentContainer, fragment,
null);
    fragment.setFragmentText(tab.getText());   }
else {
    ft.attach(fragment);   }
}   
// Called on the currently selected tab when a different tag is selected.
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
  if (fragment != null) {
    ft.detach(fragment);   }
}
// Called when the selected tab is selected.public void onTabReselected(Tab tab, FragmentTransaction ft) { // TODO React to a selected tab being selected again. } }

 

TabListenerTab绑定在一起:

 

Tab tabOne = actionBar.newTab(); 
TabListener<EarthquakeListFragment>  listTabListener = new TabListener<EarthquakeListFragment>(this, R.id.EarthquakeFragmentContainer, EarthquakeListFragment.class); 
tabOne.setTabListener(listTabListener);

 

使用下拉框导航:

actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST); 
ArrayList<CharSequence> al = new ArrayList<CharSequence>(); 
al.add(“Item 1”);al.add(“Item 2”); 
ArrayAdapter<CharSequence> dropDownAdapter = new ArrayAdapter<CharSequence>(this, android.R.layout.simple_list_item_1, al); 
// Select the drop-down navigation mode. 
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST); 
// Create a new Spinner Adapter that contains the values to  be displayed in the drop down.
ArrayAdapter dropDownAdapter =
ArrayAdapter.createFromResource(this, R.array.my_dropdown_values, android.R.layout.simple_list_item_1); // Assign the callbacks to handle drop-down selections.
actionBar.setListNavigationCallbacks(dropDownAdapter,
new OnNavigationListener() {
    public boolean onNavigationItemSelected(int itemPosition, long itemId) {
    // TODO Modify your UI based on the position of the drop down item selected.       return true; } });

使用菜单和ActionBar Item

Android Actionbar中常用的Menu类型:

1. Icon Menu:在ActionBar中以图标形式显示的Menu

2. Expanded and overflow Menu: 点击more出现的菜单,显示文本而不是图标。

3. Submenu

创建菜单

重写Activity中的onCreateOptionMenus方法可以创建菜单:

 

static final private int MENU_ITEM = Menu.FIRST; 
@Override
public
boolean onCreateOptionsMenu(Menu menu) {   super.onCreateOptionsMenu(menu);   // Group ID
  int groupId = 0;
  // Unique Menu Item identifier. Used for event handling   int menuItemId = MENU_ITEM;
  // The order position of the item
  int menuItemOrder = Menu.NONE;
  // Text to be displayed for this Menu Item
  int menuItemText = R.string.menu_item;   
// Create the Menu Item and keep a reference to it
  MenuItem menuItem = menu.add(groupId, menuItemId,
menuItemOrder, menuItemText);   return true;
}

 

创建MenuItem的几个参数:

1. MenuItem所在GroupID

2. MenuItemID,后面可以用findItem方法获取对应的MenuItem

3. MenuItem在组内的顺序

4. MenuItem显示的文本

获取已创建的MenuItem

 

MenuItem menuItem = menu.findItem(MENU_ITEM); 

 

设置MenuItem的显示方式

使用setShowAsActionFlags 方法,可以设置MenuItemActionBar中的显示:

SHOW_AS_ACTION :永远在ActionBar中显示

SHOW_AS_IF_SPACE :当ActionBar有空白位置的时候显示

MenuItem类型

1. CheckBox

 

// Create a new check box item.
menu.add(0, CHECKBOX_ITEM, Menu.NONE, “CheckBox”).setCheckable(true);

 

2. Radio Buttons:

// Create a radio button group.
menu.add(RB_GROUP, RADIOBUTTON_1, Menu.NONE, “Radiobutton 1”);
menu.add(RB_GROUP, RADIOBUTTON_2, Menu.NONE, “Radiobutton 2”);
menu.add(RB_GROUP, RADIOBUTTON_3, Menu.NONE, “Radiobutton
3”).setChecked(true);

3. 快捷键

 

// Add a shortcut to this Menu Item, ‘0’ if using the numeric keypad or ‘b’ if using the full keyboard.
menuItem.setShortcut(‘0’, ‘b’);

 

4. Condensed Title (Condensed Title是指在icon menu的状态下显示的标题,在扩展(more)那里会显示全标题。)

menuItem.setTitleCondensed(“Short Title”); 

5. icon

menuItem.setIcon(R.drawable.menu_item_icon); 

6. MenuItem Click Listener

menuItem.setOnMenuItemClickListener(new OnMenuItemClickListener() { 
  public boolean onMenuItemClick(MenuItem _menuItem) {     [ ... execute click handling, return true if handled ... ]     return true;
  } });

7. Intent

menuItem.setIntent(new Intent(this, MyOtherActivity.class)); 

Action View

menuItem.setActionView(R.layout.my_action_view).setShowAsActionFlags(MenuItem.SHOW_AS_ACTION_IF_ROOM|MenuItem.SHOW_AS_ACTION_COLLAPSE_ACTION_VIEW); 

可以在ActionView中加Button等控件:

 

View myView = menuItem.getActionView();
Button button = (Button)myView.findViewById(R.id.goButton); button.setOnClickListener(new OnClickListener() {
  public void onClick(View v) {   // TODO React to the button press. } });

 

Fragment中获取Menu Item

Fragment中调用setHasOptionsMenu方法,可以告诉Activity这个Fragment中含有MenuItem,从而使Activity获得并显示这些MenuItem。

@Override
public void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   setHasOptionsMenu(true);
}

使用XML定义MenuItem

这是目前比较推荐的添加MenuItem的方法,在res/menu中创建XML文件并将MenuItem定义写入此XML

 

<menu xmlns:android=”http://schemas.android.com/apk/res/android”> 
  <item android:id=”@+id/action_item”
      android:icon=”@drawable/action_item_icon”
      android:title=”@string/action_item_title”
      android:showAsAction=”ifRoom”>   </item>
  <item android:id=”@+id/action_view_item”
      android:icon=”@drawable/action_view_icon”
      android:title=”@string/action_view_title”
      android:showAsAction=”ifRoom|collapseActionView”
      android:actionLayout=”@layout/my_action_view”>   </item>
  <item android:id=”@+id/action_provider_item”
      android:title=”Share”
      android:showAsAction=”always”       android:actionProviderClass=”android.widget.ShareActionProvider”>
  </item>   <item android:id=”@+id/item02”
      android:checkable=”true”
      android:title=”@string/menu_item_two”>   </item>
  <item android:id=”@+id/item03”
      android:numericShortcut=”3”
      android:alphabeticShortcut=”3”
      android:title=”@string/menu_item_three”>   </item>
  <item android:id=”@+id/item04”
      android:title=”@string/submenu_title”>
    <menu>       <item android:id=”@+id/item05”
          android:title=”@string/submenu_item”>       </item>
    </menu>   </item>
</menu>

 

然后,在onCreateOptionsMenu中创建Menu

 

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

 

响应Menu选择事件

Activity中所有的Menu事件都是放在onOptionsItemSelected 中一起处理的:

public boolean onOptionsItemSelected(MenuItem item) { 
  super.onOptionsItemSelected(item); 
  // Find which Menu Item has been selected 
  switch (item.getItemId()) {     
// Check for each known Menu Item
    case (MENU_ITEM):
    [ ... Perform menu handler actions ... ]
      return true;     // Return false if you have not handled the Menu Item     default:
      return false;
  } }

子菜单和环境菜单

创建子菜单:

SubMenu sub = menu.addSubMenu(0, 0, Menu.NONE, “Submenu”); 
sub.setHeaderIcon(R.drawable.icon); sub.setIcon(R.drawable.icon); MenuItem submenuItem
= sub.add(0, 0, Menu.NONE, “Submenu Item”);

使用环境菜单和弹出菜单:

一种方法是重写View中的onCreateContextMenu方法,这样任何包含这个View的Activity都会包含这个上下文菜单。

@Override
public void onCreateContextMenu(ContextMenu menu) {   super.onCreateContextMenu(menu);   menu.add(“ContextMenuItem1”);
}

更常用的方法是重写ActivityonCreateContextMenu方法,然后在onCreate方法中调用.

registerForContextMenu(view):
@Override
public
void onCreate(Bundle savedInstanceState) {   super.onCreate(savedInstanceState);   EditText view = new EditText(this);
  setContentView(view);   registerForContextMenu(view); } @Override
public
void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
  super.onCreateContextMenu(menu, v, menuInfo);   menu.setHeaderTitle(“Context Menu”);
  menu.add(
0, Menu.FIRST, Menu.NONE, “Item 1”).setIcon(R.drawable.menu_item);
  menu.add(0, Menu.FIRST+1, Menu.NONE, “Item 2”).setCheckable(true);
  menu.add(0, Menu.FIRST+2, Menu.NONE, “Item 3”).setShortcut(‘3’, ‘3’);
  SubMenu sub = menu.addSubMenu(“Submenu”);sub.add(“Submenu Item”); }

这样,在registerForContextMenu中注册的View中长按屏幕时,就会出现这个环境菜单。

弹出菜单

创建弹出菜单并绑定到View:

final PopupMenu popupMenu = new PopupMenu(this, myView); 

创建弹出菜单并绑定到Button

final PopupMenu popupMenu = new PopupMenu(this, button); 
popupMenu.inflate(R.menu.my_popup_menu); 
popupMenu.setOnMenuItemClickListener(new OnMenuItemClickListener() { 
  public boolean onMenuItemClick(MenuItem item) { 
    switch (item.getItemId()) {       case (POPUP_ITEM_1) :
      // TODO Handle popup menu clicks.
        return true;
      default:
        return false;
    }   }
});

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