如何显示Android Action Bar徽标

Question

我正在关注Android开发者协会

我希望在操作栏的左侧有绿色机器人徽标 http://developer.android.com/images/training/basics/actionbar-theme-custom@2x.png

但我根本没有动作栏上的徽标。我搜索了几天，仍然无法找到答案。

请帮助，谢谢！

的src /.../ MainActivity.java

public class MainActivity extends ActionBarActivity {

    public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";

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

        getSupportActionBar().setDisplayUseLogoEnabled(true);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu items for use in the action bar
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.action_bar, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle presses on the action bar items
        switch (item.getItemId()) {
            case R.id.action_tab:
                ActionBar.openTab(this);
                return true;
            case R.id.action_search:
                ActionBar.openSearch(this);
                return true;
            case R.id.action_settings:
                ActionBar.openSettings(this);
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    /** Called when the user clicks the Send button */
    public void sendMessage(View view) {
        Intent intent = new Intent(this, DisplayMessageActivity.class);
        EditText editText = (EditText) findViewById(R.id.edit_message);
        String message = editText.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);
    }
}

菜单/ action_bar.xml

    <menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <!-- Tab, should appear as action button -->
    <item android:id="@+id/action_tab"
          android:title="@string/action_tab"
          app:showAsAction="always" /> <!-- you can change "always" to "ifRoom" -->
    <!-- Search, should appear as action button -->
    <item android:id="@+id/action_search"
          android:icon="@drawable/ic_action_search"
          android:title="@string/action_search"
          app:showAsAction="always" /> <!-- you can change "always" to "ifRoom|withText" -->
    <!-- Settings, should always be in the overflow -->
    <item android:id="@+id/action_settings"
          android:title="@string/action_settings"
          app:showAsAction="never" />
</menu>

RES /值/的themes.xml

<resources>
    <!-- the theme applied to the application or activity -->
    <style name="CustomActionBarTheme"
           parent="@style/Theme.AppCompat.Light">
        <item name="android:actionBarStyle">@style/MyActionBar</item>
        <item name="android:actionMenuTextColor">@color/actionbar_otherthantitleandoverflowtext</item>
        <item name="android:windowActionBarOverlay">false</item>

        <!-- Support library compatibility -->
        <item name="actionBarStyle">@style/MyActionBar</item>
        <item name="actionMenuTextColor">@color/actionbar_otherthantitleandoverflowtext</item>
        <item name="windowActionBarOverlay">false</item>
    </style>

    <!-- ActionBar styles -->
    <style name="MyActionBar"
           parent="@style/Widget.AppCompat.ActionBar">
        <item name="android:background">@color/actionbar_background</item>
        <item name="android:titleTextStyle">@style/MyActionBarTitleText</item>

        <!-- Support library compatibility -->
        <item name="background">@color/actionbar_background</item>
        <item name="titleTextStyle">@style/MyActionBarTitleText</item>
    </style>

    <!-- ActionBar title text -->
    <style name="MyActionBarTitleText"
           parent="@style/TextAppearance.AppCompat.Widget.ActionBar.Title">
        <item name="android:textColor">@color/actionbar_titletext</item>
        <!-- The textColor property is backward compatible with the Support Library -->
    </style>
</resources>

的Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myfirstapp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="11"
        android:targetSdkVersion="21" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:logo="@drawable/ic_launcher"
        android:theme="@style/CustomActionBarTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/title_activity_main" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".DisplayMessageActivity"
            android:label="@string/title_activity_display_message"
            android:parentActivityName=".MainActivity" >
            <!-- Parent activity meta-data to support 4.0 and lower -->
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.myfirstapp.MainActivity" />
        </activity>
    </application>

</manifest>