今天一起来看下Android Action Bar的示例代码，我们通过活动栏做一个简单选项菜单。下面这个例子将演示ActionBar.NAVIGATION_MODE_STANDARD、 ActionBar.NAVIGATION_MODE_TABS和 : ActionBar.NAVIGATION_MODE_STANDARD等模式的效果。最后仍然要提示大家Action Bar是Android 3.0 honeycomb才开始有的特性，老版本的SDK和固件无法使用。
public class ActionBarDisplayOptions extends Activity implements View.OnClickListener, ActionBar.TabListener {
private View mCustomView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.action_bar_display_options);
findViewById(R.id.toggle_home_as_up).setOnClickListener(this);
findViewById(R.id.toggle_show_home).setOnClickListener(this);
findViewById(R.id.toggle_use_logo).setOnClickListener(this);
findViewById(R.id.toggle_show_title).setOnClickListener(this);
findViewById(R.id.toggle_show_custom).setOnClickListener(this);
findViewById(R.id.toggle_navigation).setOnClickListener(this);
findViewById(R.id.cycle_custom_gravity).setOnClickListener(this);
mCustomView = getLayoutInflater().inflate(R.layout.action_bar_display_options_custom, null);
final ActionBar bar = getActionBar();
bar.setCustomView(mCustomView,
new ActionBar.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
bar.addTab(bar.newTab().setText("Tab 1").setTabListener(this));
bar.addTab(bar.newTab().setText("Tab 2").setTabListener(this));
bar.addTab(bar.newTab().setText("Tab 3").setTabListener(this));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.display_options_actions, menu);
return true;
}
public void onClick(View v) {
final ActionBar bar = getActionBar();
int flags = 0;
switch (v.getId()) {
case R.id.toggle_home_as_up:
flags = ActionBar.DISPLAY_HOME_AS_UP;
break;
case R.id.toggle_show_home:
flags = ActionBar.DISPLAY_SHOW_HOME;
break;
case R.id.toggle_use_logo:
flags = ActionBar.DISPLAY_USE_LOGO;
break;
case R.id.toggle_show_title:
flags = ActionBar.DISPLAY_SHOW_TITLE;
break;
case R.id.toggle_show_custom:
flags = ActionBar.DISPLAY_SHOW_CUSTOM;
break;
case R.id.toggle_navigation:
bar.setNavigationMode(
bar.getNavigationMode() == ActionBar.NAVIGATION_MODE_STANDARD
? ActionBar.NAVIGATION_MODE_TABS
: ActionBar.NAVIGATION_MODE_STANDARD);
return;
case R.id.cycle_custom_gravity:
ActionBar.LayoutParams lp = (ActionBar.LayoutParams) mCustomView.getLayoutParams();
int newGravity = 0;
switch (lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
case Gravity.LEFT:
newGravity = Gravity.CENTER_HORIZONTAL;
break;
case Gravity.CENTER_HORIZONTAL:
newGravity = Gravity.RIGHT;
break;
case Gravity.RIGHT:
newGravity = Gravity.LEFT;
break;
}
lp.gravity = lp.gravity & ~Gravity.HORIZONTAL_GRAVITY_MASK | newGravity;
bar.setCustomView(mCustomView, lp);
return;
}
int change = bar.getDisplayOptions() ^ flags;
bar.setDisplayOptions(change, flags);
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
}
接下来是文中涉及的3个xml布局文件:
相关的XML布局action_bar_display_options.xml代码为
<?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">
<Button android:id="@+id/toggle_home_as_up"
;
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/toggle_home_as_up" ;/>
<Button android:id="@+id/toggle_show_home"
;
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/toggle_show_home" ;/>
<Button android:id="@+id/toggle_use_logo"
;
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/toggle_use_logo" ;/>
<Button android:id="@+id/toggle_show_title"
;
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/toggle_show_title" ;/>
<Button android:id="@+id/toggle_show_custom"
;
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/toggle_show_custom" ;/>
<Button android:id="@+id/toggle_navigation"
;
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/toggle_navigation" ;/>
<Button android:id="@+id/cycle_custom_gravity"
;
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/cycle_custom_gravity" ;/>
</LinearLayout>
相关的自定义布局文件action_bar_display_options_custom.xml代码为
<?xml version="1.0" encoding="utf-8"?>
<Button xmlns:android="http://schemas.android.com/apk/res/android"
android:text="@string/display_options_custom_button" ;/>
相关的menu布局xml文件display_options_actions.xml代码为
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/simple_item"
;android:title="@string/display_options_menu_item" ;/>
</menu>
上面的string后的元素大家可以根据自己的情况进行替换。
ActionBar相关的示例代码第二部分分为两种，作为Android 3.0的重要特性我们直接看代码:
一、使用菜单资源构造
public class ActionBarMechanics extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().requestFeature(Window.FEATURE_ACTION_BAR);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
menu.add("Normal item");
MenuItem actionItem = menu.add("Action Button");
actionItem.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
actionItem.setIcon(android.R.drawable.ic_menu_share);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
Toast.makeText(this, "Selected Item: " + item.getTitle(), Toast.LENGTH_SHORT).show();
return true;
}
}
二、作为Tab切换Fragment
public class ActionBarTabs extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.action_bar_tabs);
}
public void onAddTab(View v) {
final ActionBar bar = getActionBar();
final int tabCount = bar.getTabCount();
final String text = "Tab " + tabCount;
bar.addTab(bar.newTab()
.setText(text)
.setTabListener(new TabListener(new TabContentFragment(text))));
}
public void onRemoveTab(View v) {
final ActionBar bar = getActionBar();
bar.removeTabAt(bar.getTabCount() - 1);
}
public void onToggleTabs(View v) {
final ActionBar bar = getActionBar();
if (bar.getNavigationMode() == ActionBar.NAVIGATION_MODE_TABS) {
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
bar.setDisplayOptions(ActionBar.DISPLAY_SHOW_TITLE, ActionBar.DISPLAY_SHOW_TITLE);
} else {
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE);
}
}
public void onRemoveAllTabs(View v) {
getActionBar().removeAllTabs();
}
private class TabListener implements ActionBar.TabListener {
private TabContentFragment mFragment;
public TabListener(TabContentFragment fragment) {
mFragment = fragment;
}
public void onTabSelected(Tab tab, FragmentTransaction ft) {
ft.add(R.id.fragment_content, mFragment, mFragment.getText());
}
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
ft.remove(mFragment);
}
public void onTabReselected(Tab tab, FragmentTransaction ft) {
Toast.makeText(ActionBarTabs.this, "Reselected!", Toast.LENGTH_SHORT).show();
}
}
private class TabContentFragment extends Fragment {
private String mText;
public TabContentFragment(String text) {
mText = text;
}
public String getText() {
return mText;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View fragView = inflater.inflate(R.layout.action_bar_tab_content, container, false);
TextView text = (TextView) fragView.findViewById(R.id.text);
text.setText(mText);
return fragView;
}
}
}
涉及的布局文件action_bar_tabs.xml代码为
<?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">
<FrameLayout android:id="@+id/fragment_content"
; android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1" />
<LinearLayout android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:orientation="vertical">
<Button android:id="@+id/btn_add_tab"
; android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/btn_add_tab"
; android:onClick="onAddTab" />
<Button android:id="@+id/btn_remove_tab"
; android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/btn_remove_tab"
; android:onClick="onRemoveTab" />
<Button android:id="@+id/btn_toggle_tabs"
; android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/btn_toggle_tabs"
; android:onClick="onToggleTabs" />
<Button android:id="@+id/btn_remove_all_tabs"
; android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/btn_remove_all_tabs"
; android:onClick="onRemoveAllTabs" />
</LinearLayout>
</LinearLayout>
涉及布局文件action_bar_tab_content.xml的代码为
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/text"
;android:layout_width="wrap_content"
android:layout_height="wrap_content" />
