如何自定義ActionBar?

[Brief]

因爲Uses-SDK指定的版本不一樣, 從而會致使一樣的代碼有可能在運行時報錯, 所以須要特別注意. 詳見 [Troubles].

[Quick Start]

1. 編寫Java代碼和XML佈局文件

public class ActivityEx extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
        setContentView(R.layout.activity_test);
        getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.custom_actionbar);
	}
}

XML佈局文件, 略.

 2. 編寫styles.xml , 自定義 Activity樣式

<style name="ActionBar.Style.WindowTitle">
	<item name="android:textColor">#fff</item>
	<item name="android:textSize">14sp</item>
	<item name="android:textStyle">bold</item>
</style>

<style name="ActionBar.Style">
	<item name="android:singleLine">true</item>
	<item name="android:textAppearance">@style/ActionBar.Style.WindowTitle</item>
	<item name="android:shadowColor">#BB000000</item>
	<item name="android:shadowRadius">2.75</item>
</style>

<style name="ActionBar.Background">
	<item name="android:background">@null</item>
</style>

<style name="ActionBar" parent="android:Theme">
	<item name="android:windowTitleStyle">@style/ActionBar.Style</item>
	<item name="android:windowTitleSize">56dp</item>
	<item name="android:windowTitleBackgroundStyle">@style/ActionBar.Background</item>
</style>

P.S. 可參考 \android-sdk\platforms\android-[$level]\data\res\values\themes.xml

3. 編輯AndroidManifest.xml, 啓用自定義樣式

<activity android:name="net.oschina.my.ActionBarTest"
	android:theme="@style/ActionBar"
	android:label="@string/app_name" >
	<intent-filter>
		<action android:name="android.intent.action.MAIN" />
		<category android:name="android.intent.category.LAUNCHER" />
	</intent-filter>
</activity>

[Troubles]

筆者當前的工程配置以下:

<uses-sdk android:minSdkVersion="8" android:targetSdkVersion="17" />

若是按照默認的工程設置, 並只編寫Java代碼, 那麼App運行時就會報錯. 
所以, 爲了保險起見, 強制設置Activity的theme, 而且該theme是繼承於android:Theme, 不然也將會報錯. 錯誤日誌以下:

You cannot combine custom titles with other title features

根據報錯日誌, 咱們能夠看到拋異常的類是: android-[$level]\com\android\internal\policy\impl\PhoneWindow.java , 從中能夠找到 requestFeature 函數, 以下:

@Override
public boolean requestFeature(int featureId) {
	if (mContentParent != null) {
		throw new AndroidRuntimeException("requestFeature() must be called before adding content");
	}
	final int features = getFeatures();
	if ((features != DEFAULT_FEATURES) && (featureId == FEATURE_CUSTOM_TITLE)) {

		/* Another feature is enabled and the user is trying to enable the custom title feature */
		throw new AndroidRuntimeException("You cannot combine custom titles with other title features");
	}
	if (((features & (1 << FEATURE_CUSTOM_TITLE)) != 0) &&
			(featureId != FEATURE_CUSTOM_TITLE) && (featureId != FEATURE_ACTION_MODE_OVERLAY)) {

		/* Custom title feature is enabled and the user is trying to enable another feature */
		throw new AndroidRuntimeException("You cannot combine custom titles with other title features");
	}
	if ((features & (1 << FEATURE_NO_TITLE)) != 0 && featureId == FEATURE_ACTION_BAR) {
		return false; // Ignore. No title dominates.
	}
	if ((features & (1 << FEATURE_ACTION_BAR)) != 0 && featureId == FEATURE_NO_TITLE) {
		// Remove the action bar feature if we have no title. No title dominates.
		removeFeature(FEATURE_ACTION_BAR);
	}
	return super.requestFeature(featureId);
}

從上面的代碼基本能夠知道, 爲何須要強制設置theme, 而且該theme仍是繼承於android:Theme.

[USAGE]

自定義標題的使用方法和View是相同的, 也是經過 findViewById(... ) 來獲取對象, 而後綁定消息事件.

[SeeAlso]

http://blog.csdn.net/pathuang68/article/details/6646792