Action Bar是一種新増的導航欄功能,在Android 3.0之後加入到系統的API當中,它標識了用戶當前操作界面的位置,並提供了額外的用戶動作、界面導航等功能。使用ActionBar的好處是,它可以給提供一種全局統一的UI界面,使得用戶在使用任何一款軟件時都懂得該如何操作,並且ActionBar還可以自動適應各種不同大小的屏幕。下面是一張使用ActionBar的界面截圖:
其中,[1]是ActionBar的圖標,[2]是兩個action按鈕,[3]是overflow按鈕。
由於Action Bar是在3.0以後的版本中加入的,如果想在2.x的版本里使用ActionBar的話則需要引入Support Library,不過3.0之前版本的市場佔有率已經非常小了,這裏簡單起見我們就不再考慮去做向下兼容,而是隻考慮4.0以上版本的用法。
添加和移除Action Bar
ActionBar的添加非常簡單,只需要在AndroidManifest.xml中指定Application或Activity的theme是Theme.Holo或其子類就可以了,而使用Eclipse創建的項目自動就會將Application的theme指定成Theme.Holo,所以ActionBar默認都是顯示出來的。新建一個空項目並運行,效果如下圖所示:
而如果想要移除ActionBar的話通常有兩種方式,一是將theme指定成Theme.Holo.NoActionBar,表示使用一個不包含ActionBar的主題,二是在Activity中調用以下方法:
- ActionBar actionBar = getActionBar();
- actionBar.hide();
- ActionBar actionBar = getActionBar();
- actionBar.hide();
修改Action Bar的圖標和標題
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:logo="@drawable/weather" >
- </activity>
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:logo="@drawable/weather" >
- </activity>
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:label="天氣"
- android:logo="@drawable/weather" >
- </activity>
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:label="天氣"
- android:logo="@drawable/weather" >
- </activity>
添加Action按鈕
- <menu xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools"
- tools:context="com.example.actionbartest.MainActivity" >
- <item
- android:id="@+id/action_compose"
- android:icon="@drawable/ic_action_compose"
- android:showAsAction="always"
- android:title="@string/action_compose"/>
- <item
- android:id="@+id/action_delete"
- android:icon="@drawable/ic_action_delete"
- android:showAsAction="always"
- android:title="@string/action_delete"/>
- <item
- android:id="@+id/action_settings"
- android:icon="@drawable/ic_launcher"
- android:showAsAction="never"
- android:title="@string/action_settings"/>
- </menu>
- <menu xmlns:android="http://schemas.android.com/apk/res/android"
- xmlns:tools="http://schemas.android.com/tools"
- tools:context="com.example.actionbartest.MainActivity" >
- <item
- android:id="@+id/action_compose"
- android:icon="@drawable/ic_action_compose"
- android:showAsAction="always"
- android:title="@string/action_compose"/>
- <item
- android:id="@+id/action_delete"
- android:icon="@drawable/ic_action_delete"
- android:showAsAction="always"
- android:title="@string/action_delete"/>
- <item
- android:id="@+id/action_settings"
- android:icon="@drawable/ic_launcher"
- android:showAsAction="never"
- android:title="@string/action_settings"/>
- </menu>
- @Override
- public boolean onCreateOptionsMenu(Menu menu) {
- MenuInflater inflater = getMenuInflater();
- inflater.inflate(R.menu.main, menu);
- return super.onCreateOptionsMenu(menu);
- }
- @Override
- public boolean onCreateOptionsMenu(Menu menu) {
- MenuInflater inflater = getMenuInflater();
- inflater.inflate(R.menu.main, menu);
- return super.onCreateOptionsMenu(menu);
- }
- 當ActionBar中的剩餘空間不足的時候,如果Action按鈕指定的showAsAction屬性是ifRoom的話,該Action按鈕就會出現在overflow當中,此時就只有title能夠顯示了。
- 如果Action按鈕在ActionBar中顯示,用戶可能通過長按該Action按鈕的方式來查看到title的內容。
響應Action按鈕的點擊事件
- @Override
- public boolean onOptionsItemSelected(MenuItem item) {
- switch (item.getItemId()) {
- case R.id.action_compose:
- Toast.makeText(this, "Compose", Toast.LENGTH_SHORT).show();
- return true;
- case R.id.action_delete:
- Toast.makeText(this, "Delete", Toast.LENGTH_SHORT).show();
- return true;
- case R.id.action_settings:
- Toast.makeText(this, "Settings", Toast.LENGTH_SHORT).show();
- return true;
- default:
- return super.onOptionsItemSelected(item);
- }
- }
- @Override
- public boolean onOptionsItemSelected(MenuItem item) {
- switch (item.getItemId()) {
- case R.id.action_compose:
- Toast.makeText(this, "Compose", Toast.LENGTH_SHORT).show();
- return true;
- case R.id.action_delete:
- Toast.makeText(this, "Delete", Toast.LENGTH_SHORT).show();
- return true;
- case R.id.action_settings:
- Toast.makeText(this, "Settings", Toast.LENGTH_SHORT).show();
- return true;
- default:
- return super.onOptionsItemSelected(item);
- }
- }
通過Action Bar圖標進行導航
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setTitle("天氣");
- setContentView(R.layout.activity_main);
- ActionBar actionBar = getActionBar();
- actionBar.setDisplayHomeAsUpEnabled(true);
- }
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setTitle("天氣");
- setContentView(R.layout.activity_main);
- ActionBar actionBar = getActionBar();
- actionBar.setDisplayHomeAsUpEnabled(true);
- }
- @Override
- public boolean onOptionsItemSelected(MenuItem item) {
- switch (item.getItemId()) {
- case android.R.id.home:
- finish();
- return true;
- ……
- }
- }
- @Override
- public boolean onOptionsItemSelected(MenuItem item) {
- switch (item.getItemId()) {
- case android.R.id.home:
- finish();
- return true;
- ……
- }
- }
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:logo="@drawable/weather" >
- <meta-data
- android:name="android.support.PARENT_ACTIVITY"
- android:value="com.example.actionbartest.LaunchActivity" />
- </activity>
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:logo="@drawable/weather" >
- <meta-data
- android:name="android.support.PARENT_ACTIVITY"
- android:value="com.example.actionbartest.LaunchActivity" />
- </activity>
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:logo="@drawable/weather"
- android:parentActivityName="com.example.actionbartest.LaunchActivity" >
- </activity>
- <activity
- android:name="com.example.actionbartest.MainActivity"
- android:logo="@drawable/weather"
- android:parentActivityName="com.example.actionbartest.LaunchActivity" >
- </activity>
- @Override
- public boolean onOptionsItemSelected(MenuItem item) {
- switch (item.getItemId()) {
- case android.R.id.home:
- Intent upIntent = NavUtils.getParentActivityIntent(this);
- if (NavUtils.shouldUpRecreateTask(this, upIntent)) {
- TaskStackBuilder.create(this)
- .addNextIntentWithParentStack(upIntent)
- .startActivities();
- } else {
- upIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
- NavUtils.navigateUpTo(this, upIntent);
- }
- return true;
- ......
- }
- }
- @Override
- public boolean onOptionsItemSelected(MenuItem item) {
- switch (item.getItemId()) {
- case android.R.id.home:
- Intent upIntent = NavUtils.getParentActivityIntent(this);
- if (NavUtils.shouldUpRecreateTask(this, upIntent)) {
- TaskStackBuilder.create(this)
- .addNextIntentWithParentStack(upIntent)
- .startActivities();
- } else {
- upIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
- NavUtils.navigateUpTo(this, upIntent);
- }
- return true;
- ......
- }
- }
添加Action View
- <menu xmlns:android="http://schemas.android.com/apk/res/android" >
- <item
- android:id="@+id/action_search"
- android:icon="@drawable/ic_action_search"
- android:actionViewClass="android.widget.SearchView"
- android:showAsAction="ifRoom|collapseActionView"
- android:title="@string/action_search" />
- ......
- </menu>
- <menu xmlns:android="http://schemas.android.com/apk/res/android" >
- <item
- android:id="@+id/action_search"
- android:icon="@drawable/ic_action_search"
- android:actionViewClass="android.widget.SearchView"
- android:showAsAction="ifRoom|collapseActionView"
- android:title="@string/action_search" />
- ......
- </menu>
- @Override
- public boolean onCreateOptionsMenu(Menu menu) {
- MenuInflater inflater = getMenuInflater();
- inflater.inflate(R.menu.main, menu);
- MenuItem searchItem = menu.findItem(R.id.action_search);
- SearchView searchView = (SearchView) searchItem.getActionView();
- // 配置SearchView的屬性
- ......
- return super.onCreateOptionsMenu(menu);
- }
- @Override
- public boolean onCreateOptionsMenu(Menu menu) {
- MenuInflater inflater = getMenuInflater();
- inflater.inflate(R.menu.main, menu);
- MenuItem searchItem = menu.findItem(R.id.action_search);
- SearchView searchView = (SearchView) searchItem.getActionView();
- // 配置SearchView的屬性
- ......
- return super.onCreateOptionsMenu(menu);
- }
- @Override
- public boolean onCreateOptionsMenu(Menu menu) {
- MenuInflater inflater = getMenuInflater();
- inflater.inflate(R.menu.main, menu);
- MenuItem searchItem = menu.findItem(R.id.action_search);
- searchItem.setOnActionExpandListener(new OnActionExpandListener() {
- @Override
- public boolean onMenuItemActionExpand(MenuItem item) {
- Log.d("TAG", "on expand");
- return true;
- }
- @Override
- public boolean onMenuItemActionCollapse(MenuItem item) {
- Log.d("TAG", "on collapse");
- return true;
- }
- });
- return super.onCreateOptionsMenu(menu);
- }
- @Override
- public boolean onCreateOptionsMenu(Menu menu) {
- MenuInflater inflater = getMenuInflater();
- inflater.inflate(R.menu.main, menu);
- MenuItem searchItem = menu.findItem(R.id.action_search);
- searchItem.setOnActionExpandListener(new OnActionExpandListener() {
- @Override
- public boolean onMenuItemActionExpand(MenuItem item) {
- Log.d("TAG", "on expand");
- return true;
- }
- @Override
- public boolean onMenuItemActionCollapse(MenuItem item) {
- Log.d("TAG", "on collapse");
- return true;
- }
- });
- return super.onCreateOptionsMenu(menu);
- }
Overflow按鈕不顯示的情況
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- ......
- setOverflowShowingAlways();
- }
- private void setOverflowShowingAlways() {
- try {
- ViewConfiguration config = ViewConfiguration.get(this);
- Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");
- menuKeyField.setAccessible(true);
- menuKeyField.setBoolean(config, false);
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- ......
- setOverflowShowingAlways();
- }
- private void setOverflowShowingAlways() {
- try {
- ViewConfiguration config = ViewConfiguration.get(this);
- Field menuKeyField = ViewConfiguration.class.getDeclaredField("sHasPermanentMenuKey");
- menuKeyField.setAccessible(true);
- menuKeyField.setBoolean(config, false);
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
讓Overflow中的選項顯示圖標
- @Override
- public boolean onMenuOpened(int featureId, Menu menu) {
- if (featureId == Window.FEATURE_ACTION_BAR && menu != null) {
- if (menu.getClass().getSimpleName().equals("MenuBuilder")) {
- try {
- Method m = menu.getClass().getDeclaredMethod("setOptionalIconsVisible", Boolean.TYPE);
- m.setAccessible(true);
- m.invoke(menu, true);
- } catch (Exception e) {
- }
- }
- }
- return super.onMenuOpened(featureId, menu);
- }
- @Override
- public boolean onMenuOpened(int featureId, Menu menu) {
- if (featureId == Window.FEATURE_ACTION_BAR && menu != null) {
- if (menu.getClass().getSimpleName().equals("MenuBuilder")) {
- try {
- Method m = menu.getClass().getDeclaredMethod("setOptionalIconsVisible", Boolean.TYPE);
- m.setAccessible(true);
- m.invoke(menu, true);
- } catch (Exception e) {
- }
- }
- }
- return super.onMenuOpened(featureId, menu);
- }