SystemUI Plugins
SystemUI插件提供了一种快速替换SystemUI原有组件的方法，可以在运行时更改SystemUI的行为。
现在已有插件：
here
一、使用方法
1. Plugin 接口
在包com.android.systemui.plugins中定义SystemUI 和 Plugin 中共同使用的接口：
@ProvidesInterface(action = MyPlugin.ACTION, version = MyPlugin.VERSION)
@DependsOn(target = OtherInterface.class)
public interface MyPlugin extends Plugin {
String ACTION = "com.android.systemui.action.PLUGIN_MY_PLUGIN";
int VERSION = 1;
...
}
- VERSION: 解决兼容性问题，每次增加或者修改接口，VERSION需要增大， 以避免Plugin接口没有默认实现
- ACTION： 用于关联Plugin apk 中声明的组件
2. Plugin Listener
可以通过 PluginManager注册监听器PluginListener， 可以实现在相应插件安装时调用方法
public interface PluginListener<T extends Plugin> {
/**
* Called when the plugin has been loaded and is ready to be used.
* This may be called multiple times if multiple plugins are allowed.
* It may also be called in the future if the plugin package changes
* and needs to be reloaded.
*/
void onPluginConnected(T plugin);
/**
* Called when a plugin has been uninstalled/updated and should be removed
* from use.
*/
default void onPluginDisconnected(T plugin) {
// Optional.
}
}
3. 使用实例
在SystemUI编译PluginLib.aar, 让Plugin apk 依赖这个lib
AndroidManifest.xml
<service android:name=".SampleOverlayPlugin"
android:label="@string/plugin_label">
<intent-filter>
<action android:name="com.android.systemui.action.PLUGIN_OVERLAY" />
</intent-filter>
</service>
可以通过PackageManagerService 去查找组件
-
可以方便的通过PMS 结果禁用/启用组件
permission
<uses-permission android:name="com.android.systemui.permission.PLUGIN" />
- 实现接口
@Requires(target = OverlayPlugin.class, version = OverlayPlugin.VERSION)
public class SampleOverlayPlugin implements OverlayPlugin {
...
public void onCreate(Context sysuiContext, Context pluginContext) {
}
public void onDestroy() {
}
}
二、设计原理
1. crash处理
PluginManagerImpl中定义了一个UncaughtExceptionHandler， 在发生crash 时检查是否为插件引起，如果是，并且插件不在白名单中，则禁用插件
白名单配置：
res/values/config.xml
<!-- SystemUI Plugins that can be loaded on user builds. -->
<string-array name="config_pluginWhitelist" translatable="false">
<item>com.android.systemui</item>
<item>com.systemui.plugin</item>
</string-array>
白名单中插件在每次SystemUI 进程启动时加载
2. 插件加载流程
插件加载时机： SystemUI 进程启动 或者 插件apk 安装（监听 Intent.ACTION_PACKAGE_ADDED 广播）
SystemUIService.onCreate
-> VolumeUI.start()
-> new VolumeDialogComponent()
-> ExtensionBuilder.withPlugin
-> PluginManagerImpl.addPluginListener
->PluginInstanceManagerFactory.createPluginInstanceManager
一个插件组件对应一个PluginInstanceManager
com/android/systemui/plugins/PluginInstanceManager.java
protected PluginInfo<T> handleLoadPlugin(ComponentName component) {
... ...
try {
ApplicationInfo info = mPm.getApplicationInfo(pkg, 0);
// TODO: This probably isn't needed given that we don't have IGNORE_SECURITY on
if (mPm.checkPermission(PLUGIN_PERMISSION, pkg)
!= PackageManager.PERMISSION_GRANTED) {
Log.d(TAG, "Plugin doesn't have permission: " + pkg);
return null;
}
// Create our own ClassLoader so we can use our own code as the parent.
//1. 创建plugin classloader
ClassLoader classLoader = mManager.getClassLoader(info);
//2. 创建plugin Context
Context pluginContext = new PluginContextWrapper(
mContext.createApplicationContext(info, 0), classLoader);
Class<?> pluginClass = Class.forName(cls, true, classLoader);
// TODO: Only create the plugin before version check if we need it for
// legacy version check.
T plugin = (T) pluginClass.newInstance();
try {
//3. 检查版本
VersionInfo version = checkVersion(pluginClass, plugin, mVersion);
if (DEBUG) Log.d(TAG, "createPlugin");
return new PluginInfo(pkg, cls, plugin, pluginContext, version);
} catch (InvalidVersionException e) {
// 处理版本不一致情况 ...
... ...
} catch (Throwable e) {
Log.w(TAG, "Couldn't load plugin: " + pkg, e);
return null;
}
}
这个方法中做了以下工作：
创建plugin classloader
创建plugin Context
-
检查version :
版本不一致会弹出通知 ：
"Plugin xxx is too old..." 或者 "Plugin xxx is too new...", 也不会继续加再这个插件了
3. ClassLoader
只有"com.android.systemui.plugin" 包名为这个时，使用SystemUI 类加载器， 即PluginLib 中类
SystemUI/shared/src/com/android/systemui/shared/plugins/PluginManagerImpl.java
private static class ClassLoaderFilter extends ClassLoader {
private final String mPackage;
private final ClassLoader mBase;
public ClassLoaderFilter(ClassLoader base, String pkg) {
super(ClassLoader.getSystemClassLoader());
mBase = base;
mPackage = pkg;
}
@Override
protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
if (!name.startsWith(mPackage)) super.loadClass(name, resolve);
return mBase.loadClass(name);
}
}
4. Plugin Context
Context 创建
Context pluginContext = new PluginContextWrapper(
mContext.createApplicationContext(info, 0), classLoader);
注意事项
1.PluginDependency
SystemUI中 通过 Dependency.get(XXX.class)获取依赖项
Plugin 中可以通过PluginDependency 获取的SystemUI 组件
VolumeDialogController - Mostly just API for the volume plugin
ActivityStarter - Allows starting of intents while co-operating with keyguard unlocks.
如何添加：
- 将接口放到com.android.systemui.plugins包下面
- 调用PluginDependencyProvider.allowPluginDependency
src/com/android/systemui/volume/VolumeDialogComponent.java
@Inject
public VolumeDialogComponent(Context context, KeyguardViewMediator keyguardViewMediator,
VolumeDialogControllerImpl volumeDialogController) {
...
// Allow plugins to reference the VolumeDialogController.
Dependency.get(PluginDependencyProvider.class)
.allowPluginDependency(VolumeDialogController.class);
}
2.注解
Requires , DependsOn
@Requires(target = VolumeDialog.class, version = VolumeDialog.VERSION)
@DependsOn(target = Callback.class)
@Requires(target = VolumeDialogController.class, version = VolumeDialogController.VERSION)
@Requires(target = PluginDependency.class, version = PluginDependency.VERSION)
@Dependencies({@DependsOn(
target = VolumeDialogController.StreamState.class
), @DependsOn(
target = VolumeDialogController.State.class
), @DependsOn(
target = VolumeDialogController.Callbacks.class
)})
public class VolumeDialogPlugin implements VolumeDialog {
private VolumeDialogController mController;
@Override
public void init(int i, Callback callback) {
}
@Override
public void destroy() {
}
@Override
public void onCreate(Context sysuiContext, Context pluginContext) {
}
@Override
public void onDestroy() {
}
private final VolumeDialog.Callback mVolumeDialogCallback = new VolumeDialog.Callback() {
@Override
public void onZenSettingsClicked() {
}
@Override
public void onZenPrioritySettingsClicked() {
}
};
}
3. ClassNotFoundException
plugin context 中Resources 对象 ClassLoader对象 为null,在加载资源时候，如果没用Context ClassLoader ，如 DrawableInflater ,会抛找不到类异常，用下面方法可以解决
setResourceClassLoader(context.getResources(), context.getClassLoader());
public void setResourceClassLoader(Resources resources, ClassLoader classLoader) {
try {
Field field = Resources.class.getDeclaredField("mClassLoader");
field.setAccessible(true);
Object object = field.get(resources);
field.set(resources, classLoader);
} catch (IllegalAccessException | NoSuchFieldException e) {
e.printStackTrace();
}
}
参考文档
https://android.googlesource.com/platform/frameworks/base/+/master/packages/SystemUI/docs/plugins.md
