滴滴开源Android插件化框架VirtualAPK原理分析

概述

滴滴出行公司的首个对外开源项目 - VirtualAPK。地址:https://github.com/didi/VirtualAPK

滴滴自行研发了这款插件化框架,功能全面、兼容性好,还能够适用于有耦合的业务插件,这就是VirtualAPK存在的意义。业内认为,在加载耦合插件方面,VirtualAPK可以说是开源方案的首选。据说滴滴打车里面已经用上了,所以还是有必要一探究竟的~~

VirtualAPK 的工作流程如图所示:

这里写图片描述

VirtualAPK 对于插件没有额外的约束,原生的 apk 即可作为一个插件。插件工程编译生成 apk 后,通过宿主 App 加载,每个插件 apk 被加载后,都会在宿主中创建一个单独的 LoadedPlugin 对象。如上图所示,通过这些 LoadedPlugin 对象,VirtualAPK 就可以管理插件并赋予插件新的意义,使其可以像手机中安装过的App一样运行。

Activity 支持

Hook ActivityManagerService

插件化支持首先要解决的一点就是插件里的Activity并未在宿主程序的 AndroidMainfest.xml 注册,常规方法肯定无法直接启动插件的Activity,这个时候就需要去了解Activity的启动流程,关于启动过程主要的几个步骤请参考:浅析Android Activity的启动过程

从上文中可知,Activity 启动实际上是调用了 Instrumentation.execStartActivity 这个方法。源码如下:

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public ActivityResult execStartActivity(Context who, IBinder contextThread, IBinder token, Activity target,
Intent intent, int requestCode, Bundle options) {
IApplicationThread whoThread = (IApplicationThread) contextThread;
if (mActivityMonitors != null) {
synchronized (mSync) {
final int N = mActivityMonitors.size();
for (int i=0; i<N; i++) { //先查找一遍看是否存在这个activity
final ActivityMonitor am = mActivityMonitors.get(i);
if (am.match(who, null, intent)) {
am.mHits++;
if (am.isBlocking()) {
return requestCode >= 0 ? am.getResult() : null;
}
break;
}
}
}
}
try {
intent.migrateExtraStreamToClipData();
intent.prepareToLeaveProcess();
//这里才是真正打开activity的地方,其核心功能在whoThread中完成。
int result = ActivityManagerNative.getDefault().startActivity(whoThread, who.getBasePackageName(), intent,
intent.resolveTypeIfNeeded(who.getContentResolver()),token, target != null ? target.mEmbeddedID : null,
requestCode, 0, null, options);
checkStartActivityResult(result, intent); // 处理各种异常,如ActivityNotFound
} catch (RemoteException e) {
}
return null;
}

可见, startActivity 最终通过 ActivityManagerNative.getDefault() 远程调用了AMS的startActivity方法, ActivityManagerNative 实际上就是 ActivityManagerService 这个远程对象的 Binder 代理对象,每次需要与AMS交互时,需要通过这个 Binder 对象完成远程IPC调用。

还不了解Binder的童鞋,可以看看老罗的Android进程间通信(IPC)机制Binder简要介绍和学习计划

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// ActivityManagerNative.getDefault()
static public IActivityManager getDefault() {
return gDefault.get();
}
private static final Singleton<iactivitymanager> gDefault =
new Singleton<iactivitymanager>() {
protected IActivityManager create() {
IBinder b = ServiceManager.getService("activity");
if (false) {
Log.v("ActivityManager", "default service binder = " + b);
}
IActivityManager am = asInterface(b);
if (false) {
Log.v("ActivityManager", "default service = " + am);
}
return am;
}
};
从这我们可以知道,ActivityManagerNative.getDefault() 实际上是返回了一个 IActivityManager 的单例对象。
那么,VirtualApk 所要做的第一件事,就是把这个 AMS 代理对象保存起来。首先,我们可以看一下 VirtualApk 核心库里面 com.didi.virtualapk.PluginManager 这个类的初始化:
```java
// 构造方法
private PluginManager(Context context) {
Context app = context.getApplicationContext();
if (app == null) {
this.mContext = context;
} else {
this.mContext = ((Application)app).getBaseContext();
}
prepare();
}
// 初始化
private void prepare() {
Systems.sHostContext = getHostContext();
this.hookInstrumentationAndHandler();
this.hookSystemServices();
}
/**
* Hook 出一个IActivityManager,也就是 AMS 的代理对象
*/
private void hookSystemServices() {
try {
// 反射调用 ActivityManagerNative.getDefault(),实际上这在6.0中是公开的静态方法,反射可能是考虑到版本兼容性吧?
Singleton<IActivityManager> defaultSingleton = (Singleton<IActivityManager>) ReflectUtil.getField(ActivityManagerNative.class, null, "gDefault");
// 通过动态代理的方式去创建代理对象,之后所有ActivityManagerNative中的方法被调用的时候都会经过这个代理
IActivityManager activityManagerProxy = ActivityManagerProxy.newInstance(this, defaultSingleton.get());
// Hook IActivityManager from ActivityManagerNative,实际上就是把 ActivityManagerNative 替换为刚创建的 activityManagerProxy
ReflectUtil.setField(defaultSingleton.getClass().getSuperclass(), defaultSingleton, "mInstance", activityManagerProxy);
if (defaultSingleton.get() == activityManagerProxy) {
// 两者一样,保存下来
this.mActivityManager = activityManagerProxy;
}
} catch (Exception e) {
e.printStackTrace();
}
}

实际上除了 startActivity 是调用 AMS 的方法以外,startService, bindService 等方法,最终调用到AMS的里的方法,这个我们在动态代理类 com.didi.virtualapk.delegate.ActivityManagerProxy 也可以找到:

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@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if ("startService".equals(method.getName())) {
try {
// 执行自定义的 startService 过程,后面会提到
return startService(proxy, method, args);
} catch (Throwable e) {
Log.e(TAG, "Start service error", e);
}
} else if ("stopService".equals(method.getName())) {
try {
return stopService(proxy, method, args);
} catch (Throwable e) {
Log.e(TAG, "Stop Service error", e);
}
} else if ("stopServiceToken".equals(method.getName())) {
try {
return stopServiceToken(proxy, method, args);
} catch (Throwable e) {
Log.e(TAG, "Stop service token error", e);
}
} else if ("bindService".equals(method.getName())) {
try {
return bindService(proxy, method, args);
} catch (Throwable e) {
e.printStackTrace();
}
} else if ("unbindService".equals(method.getName())) {
try {
return unbindService(proxy, method, args);
} catch (Throwable e) {
e.printStackTrace();
}
} else if ("getIntentSender".equals(method.getName())) {
try {
getIntentSender(method, args);
} catch (Exception e) {
e.printStackTrace();
}
} else if ("overridePendingTransition".equals(method.getName())){
try {
overridePendingTransition(method, args);
} catch (Exception e){
e.printStackTrace();
}
}
try {
// sometimes system binder has problems.
return method.invoke(this.mActivityManager, args);
} catch (Throwable th) {
Throwable c = th.getCause();
if (c != null && c instanceof DeadObjectException) {
// retry connect to system binder
IBinder ams = ServiceManager.getService(Context.ACTIVITY_SERVICE);
if (ams != null) {
IActivityManager am = ActivityManagerNative.asInterface(ams);
mActivityManager = am;
}
}
Throwable cause = th;
do {
if (cause instanceof RemoteException) {
throw cause;
}
} while ((cause = cause.getCause()) != null);
throw c != null ? c : th;
}
}

所以实际上就等同于我们重写了一些 Activity、Service 的相关操作。具体做些什么,后面会提到~

Hook Instrumentation

回过头去看看 Instrumentation.execStartActivity 这个方法,在最后有这么一句代码:

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checkStartActivityResult(result, intent); // 处理各种异常,如ActivityNotFound
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static void checkStartActivityResult(int res, Object intent) {
if (res >= ActivityManager.START_SUCCESS) {
return;
}
switch (res) {
case ActivityManager.START_INTENT_NOT_RESOLVED:
case ActivityManager.START_CLASS_NOT_FOUND:
if (intent instanceof Intent && ((Intent)intent).getComponent() != null)
throw new ActivityNotFoundException(
"Unable to find explicit activity class "
+ ((Intent)intent).getComponent().toShortString()
+ "; have you declared this activity in your AndroidManifest.xml?");
throw new ActivityNotFoundException(
"No Activity found to handle " + intent);
case ActivityManager.START_PERMISSION_DENIED:
throw new SecurityException("Not allowed to start activity "
+ intent);
case ActivityManager.START_FORWARD_AND_REQUEST_CONFLICT:
throw new AndroidRuntimeException(
"FORWARD_RESULT_FLAG used while also requesting a result");
case ActivityManager.START_NOT_ACTIVITY:
throw new IllegalArgumentException(
"PendingIntent is not an activity");
default:
throw new AndroidRuntimeException("Unknown error code "
+ res + " when starting " + intent);
}
}

相信大家对上面的这些异常信息不陌生吧,其中最熟悉的非 Unable to find explicit activity class 莫属了,如果 Activity 没有在 AndroidMainfest.xml 注册,将会抛出此异常。

那么就得思考一个问题了,插件的 Activity 并未在宿主程序的 AndroidMainfest.xml 注册,要如何才能绕过这一层检测?

前文中提到,com.didi.virtualapk.PluginManager 这个类的初始化的时候,除了 Hook 出一个 AMS 代理对象以外,还 Hook 出一个 Instrumentation 对象。代码如下:

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private void hookInstrumentationAndHandler() {
try {
Instrumentation baseInstrumentation = ReflectUtil.getInstrumentation(this.mContext);
if (baseInstrumentation.getClass().getName().contains("lbe")) {
// reject executing in paralell space, for example, lbe.
System.exit(0);
}
// 创建自定义的 instrumentation,重写了 newActivity() 等一些方法
// baseInstrumentation 后面还会用到,也保存下来
final VAInstrumentation instrumentation = new VAInstrumentation(this, baseInstrumentation);
// 获取 ActivityThread 的实例
Object activityThread = ReflectUtil.getActivityThread(this.mContext);
// 用自定义的 instrumentation 替换掉 ActivityThread 里面的 instrumentation
ReflectUtil.setInstrumentation(activityThread, instrumentation);
ReflectUtil.setHandlerCallback(this.mContext, instrumentation);
this.mInstrumentation = instrumentation;
} catch (Exception e) {
e.printStackTrace();
}
}

既然 Activity 的启动,中间走了 Instrumentation.execStartActivity 这个方法,那么我们大概可以知道,Hook 出一个 Instrumentation 对象用来做什么了,实际上就是用来帮助启动插件的 Activity。

启动插件Activity

我们 Hook 了一个 VAInstrumentation 以替代系统的 Instrumentation,这样当系统通过 ActivityThread 调用 它的的成员变量 mInstrumentation 的 newActivity() 等方法的时候,实际是调用我们 VAInstrumentation 的 newActivity()。

实际上对于插件 Activity 启动,采用的是宿主 manifest 中占坑的方式来绕过系统校验,然后再加载真正的activity。

什么是占坑?就是构造一系列假的 Activity 替身,在 AndroidMainfest.xml 里面进行注册,以绕过检测,然后到了真正启动 Activity 的时候,再把它变回,去启动真正的目标 Activity。那么这一步是怎么做的呢?

我们可以打开核心库里面的 AndroidMainfest.xml 看看:

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<application>
<!-- Stub Activities -->
<activity android:name=".A$1" android:launchMode="standard"/>
<activity android:name=".A$2" android:launchMode="standard"
android:theme="@android:style/Theme.Translucent" />
<!-- Stub Activities -->
<activity android:name=".B$1" android:launchMode="singleTop"/>
<activity android:name=".B$2" android:launchMode="singleTop"/>
<activity android:name=".B$3" android:launchMode="singleTop"/>
<activity android:name=".B$4" android:launchMode="singleTop"/>
<activity android:name=".B$5" android:launchMode="singleTop"/>
<activity android:name=".B$6" android:launchMode="singleTop"/>
<activity android:name=".B$7" android:launchMode="singleTop"/>
<activity android:name=".B$8" android:launchMode="singleTop"/>
<!-- Stub Activities -->
<activity android:name=".C$1" android:launchMode="singleTask"/>
<activity android:name=".C$2" android:launchMode="singleTask"/>
<activity android:name=".C$3" android:launchMode="singleTask"/>
<activity android:name=".C$4" android:launchMode="singleTask"/>
<activity android:name=".C$5" android:launchMode="singleTask"/>
<activity android:name=".C$6" android:launchMode="singleTask"/>
<activity android:name=".C$7" android:launchMode="singleTask"/>
<activity android:name=".C$8" android:launchMode="singleTask"/>
<!-- Stub Activities -->
<activity android:name=".D$1" android:launchMode="singleInstance"/>
<activity android:name=".D$2" android:launchMode="singleInstance"/>
<activity android:name=".D$3" android:launchMode="singleInstance"/>
<activity android:name=".D$4" android:launchMode="singleInstance"/>
<activity android:name=".D$5" android:launchMode="singleInstance"/>
<activity android:name=".D$6" android:launchMode="singleInstance"/>
<activity android:name=".D$7" android:launchMode="singleInstance"/>
<activity android:name=".D$8" android:launchMode="singleInstance"/>
</application>

可以发现,在清单里面注册了一堆假的 StubActivity。 ABCD分别对应不同的启动模式,那么,我们启动插件的 Activity 的时候,是如何把它改为清单里面已注册的这些假的 Activity 名呢?

在 VAInstrumentation 里面,重写了 startActivity 的必经之路,就是 execStartActivity() 方法:

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public ActivityResult execStartActivity(
Context who, IBinder contextThread, IBinder token, Activity target,
Intent intent, int requestCode, Bundle options) {
// 这里面做了一系列操作,实际上就是查找插件里面第一个符合隐式条件的第一个ResolveInfo,并设置进intent
mPluginManager.getComponentsHandler().transformIntentToExplicitAsNeeded(intent);
// null component is an implicitly intent
if (intent.getComponent() != null) {
Log.i(TAG, String.format("execStartActivity[%s : %s]", intent.getComponent().getPackageName(),
intent.getComponent().getClassName()));
// !!! 重头戏在这里,用那些注册的假的StubActivity来替换真实的Activity,以绕过检测 !!!
this.mPluginManager.getComponentsHandler().markIntentIfNeeded(intent);
}
ActivityResult result = realExecStartActivity(who, contextThread, token, target,
intent, requestCode, options);
return result;
}
private ActivityResult realExecStartActivity(
Context who, IBinder contextThread, IBinder token, Activity target,
Intent intent, int requestCode, Bundle options) {
ActivityResult result = null;
try {
Class[] parameterTypes = {Context.class, IBinder.class, IBinder.class, Activity.class, Intent.class,
int.class, Bundle.class};
result = (ActivityResult)ReflectUtil.invoke(Instrumentation.class, mBase,
"execStartActivity", parameterTypes,
who, contextThread, token, target, intent, requestCode, options);
} catch (Exception e) {
e.printStackTrace();
}
return result;
}

那么,是如何替换 StubActivity 的呢? 跟进代码:

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public void markIntentIfNeeded(Intent intent) {
if (intent.getComponent() == null) {
return;
}
String targetPackageName = intent.getComponent().getPackageName();
String targetClassName = intent.getComponent().getClassName();
// 判断是否是启动插件的Activity
if (!targetPackageName.equals(mContext.getPackageName()) && mPluginManager.getLoadedPlugin(targetPackageName) != null) {
// 做标记
intent.putExtra(Constants.KEY_IS_PLUGIN, true);
// 保存真实的意图
intent.putExtra(Constants.KEY_TARGET_PACKAGE, targetPackageName);
intent.putExtra(Constants.KEY_TARGET_ACTIVITY, targetClassName);
dispatchStubActivity(intent);
}
}
/**
* 真正的转换就在这里。根据启动模式,转换对应的 StubActivity
*/
private void dispatchStubActivity(Intent intent) {
ComponentName component = intent.getComponent();
String targetClassName = intent.getComponent().getClassName();
LoadedPlugin loadedPlugin = mPluginManager.getLoadedPlugin(intent);
ActivityInfo info = loadedPlugin.getActivityInfo(component);
if (info == null) {
throw new RuntimeException("can not find " + component);
}
int launchMode = info.launchMode;
// 临时替换主题
Resources.Theme themeObj = loadedPlugin.getResources().newTheme();
themeObj.applyStyle(info.theme, true);
// 实际上就是这一句,完成转换
String stubActivity = mStubActivityInfo.getStubActivity(targetClassName, launchMode, themeObj);
Log.i(TAG, String.format("dispatchStubActivity,[%s -> %s]", targetClassName, stubActivity));
intent.setClassName(mContext, stubActivity);
}

继续跟进代码:

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class StubActivityInfo {
public static final int MAX_COUNT_STANDARD = 1;
public static final int MAX_COUNT_SINGLETOP = 8;
public static final int MAX_COUNT_SINGLETASK = 8;
public static final int MAX_COUNT_SINGLEINSTANCE = 8;
public static final String corePackage = "com.didi.virtualapk.core";
// 这个格式,就是那些假的Activity的名字
public static final String STUB_ACTIVITY_STANDARD = "%s.A$%d";
public static final String STUB_ACTIVITY_SINGLETOP = "%s.B$%d";
public static final String STUB_ACTIVITY_SINGLETASK = "%s.C$%d";
public static final String STUB_ACTIVITY_SINGLEINSTANCE = "%s.D$%d";
public final int usedStandardStubActivity = 1;
public int usedSingleTopStubActivity = 0;
public int usedSingleTaskStubActivity = 0;
public int usedSingleInstanceStubActivity = 0;
private HashMap<String, String> mCachedStubActivity = new HashMap<>();
/**
* 在这里根据启动模式及主题构造 StubActivity
*/
public String getStubActivity(String className, int launchMode, Theme theme) {
String stubActivity= mCachedStubActivity.get(className);
if (stubActivity != null) {
return stubActivity;
}
TypedArray array = theme.obtainStyledAttributes(new int[]{
android.R.attr.windowIsTranslucent,
android.R.attr.windowBackground
});
boolean windowIsTranslucent = array.getBoolean(0, false);
array.recycle();
if (Constants.DEBUG) {
Log.d("StubActivityInfo", "getStubActivity, is transparent theme ? " + windowIsTranslucent);
}
stubActivity = String.format(STUB_ACTIVITY_STANDARD, corePackage, usedStandardStubActivity);
switch (launchMode) {
case ActivityInfo.LAUNCH_MULTIPLE: {
stubActivity = String.format(STUB_ACTIVITY_STANDARD, corePackage, usedStandardStubActivity);
if (windowIsTranslucent) {
stubActivity = String.format(STUB_ACTIVITY_STANDARD, corePackage, 2);
}
break;
}
case ActivityInfo.LAUNCH_SINGLE_TOP: {
usedSingleTopStubActivity = usedSingleTopStubActivity % MAX_COUNT_SINGLETOP + 1;
stubActivity = String.format(STUB_ACTIVITY_SINGLETOP, corePackage, usedSingleTopStubActivity);
break;
}
case ActivityInfo.LAUNCH_SINGLE_TASK: {
usedSingleTaskStubActivity = usedSingleTaskStubActivity % MAX_COUNT_SINGLETASK + 1;
stubActivity = String.format(STUB_ACTIVITY_SINGLETASK, corePackage, usedSingleTaskStubActivity);
break;
}
case ActivityInfo.LAUNCH_SINGLE_INSTANCE: {
usedSingleInstanceStubActivity = usedSingleInstanceStubActivity % MAX_COUNT_SINGLEINSTANCE + 1;
stubActivity = String.format(STUB_ACTIVITY_SINGLEINSTANCE, corePackage, usedSingleInstanceStubActivity);
break;
}
default:break;
}
mCachedStubActivity.put(className, stubActivity);
return stubActivity;
}
}

到这一步,就基本清晰了。同样的,既然变为了 StubActivity,那么真正启动的时候还得变回来才行。来看一下重写后的 newActivity() 方法:

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@Override
public Activity newActivity(ClassLoader cl, String className, Intent intent) throws InstantiationException, IllegalAccessException, ClassNotFoundException {
try {
cl.loadClass(className);
} catch (ClassNotFoundException e) {
// 根据 intent 类型,去获取相应的插件
LoadedPlugin plugin = this.mPluginManager.getLoadedPlugin(intent);
// 这里就是从Intent中取出我们刚才保存的真正的意图
String targetClassName = PluginUtil.getTargetActivity(intent);
Log.i(TAG, String.format("newActivity[%s : %s]", className, targetClassName));
if (targetClassName != null) {
// mBase 是未替换之前的 Instrumentation 对象,所以这个实际上是交给系统原先的 Instrumentation 对象去执行,所以这个模式其实也可以理解为与动态代理等同
// plugin.getClassLoader() 是自己构造的一个 DexClassLoader,专门用于加载对应的apk里面的类
Activity activity = mBase.newActivity(plugin.getClassLoader(), targetClassName, intent);
activity.setIntent(intent);
try {
// for 4.1+
ReflectUtil.setField(ContextThemeWrapper.class, activity, "mResources", plugin.getResources());
} catch (Exception ignored) {
// ignored.
}
return activity;
}
}
return mBase.newActivity(cl, className, intent);
}

到这里,插件的 Activity 启动流程分析,就基本结束了。细节方面,没法一步到位,还需要大家边看源码边理解,这样才能看得更透彻。

Service 支持

对于 Service 的支持,采用动态代理AMS,拦截 Service 相关的请求,将其中转给Service Runtime去处理,Service Runtime会接管系统的所有操作。

对于我们动态代理AMS,在上一节 Activity支持 中已经介绍过了,那么,简单的来看一下 ActivityManagerProxy 是如何启动一个Service的。

在执行 startService 等方法的时候,AMS 代理对象会相应的来执行以下这些方法:

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private Object startService(Object proxy, Method method, Object[] args) throws Throwable {
IApplicationThread appThread = (IApplicationThread) args[0];
Intent target = (Intent) args[1];
ResolveInfo resolveInfo = this.mPluginManager.resolveService(target, 0);
if (null == resolveInfo || null == resolveInfo.serviceInfo) {
// is host service
return method.invoke(this.mActivityManager, args);
}
return startDelegateServiceForTarget(target, resolveInfo.serviceInfo, null, RemoteService.EXTRA_COMMAND_START_SERVICE);
}
private ComponentName startDelegateServiceForTarget(Intent target, ServiceInfo serviceInfo, Bundle extras, int command) {
Intent wrapperIntent = wrapperTargetIntent(target, serviceInfo, extras, command);
return mPluginManager.getHostContext().startService(wrapperIntent);
}
private Intent wrapperTargetIntent(Intent target, ServiceInfo serviceInfo, Bundle extras, int command) {
// fill in service with ComponentName
target.setComponent(new ComponentName(serviceInfo.packageName, serviceInfo.name));
String pluginLocation = mPluginManager.getLoadedPlugin(target.getComponent()).getLocation();
// 这里进行判断,看是交给 LocalService,还是 RemoteService 处理
// LocalService 和 RemoteService 分别对应是否在新的进程中启动Activity
boolean local = PluginUtil.isLocalService(serviceInfo);
Class<? extends Service> delegate = local ? LocalService.class : RemoteService.class;
Intent intent = new Intent();
intent.setClass(mPluginManager.getHostContext(), delegate);
intent.putExtra(RemoteService.EXTRA_TARGET, target);
// 保存一下这个的Command,对应执行不同操作
intent.putExtra(RemoteService.EXTRA_COMMAND, command);
intent.putExtra(RemoteService.EXTRA_PLUGIN_LOCATION, pluginLocation);
if (extras != null) {
intent.putExtras(extras);
}
return intent;
}

实际上包括我们调用 stopService(),AMS 代理对象最后变换后的意图,同样也是上面代码的最后两个个方法 startDelegateServiceForTarget 和 wrapperTargetIntent(),只不过 command 不一样。

所以本质上 AMS 作为代理,不管你执行启动或者关闭插件里面的 Service,他都是调用 LocalService 或者 RemoteService 的 startService 方法,在 LocalService 或者 RemoteService 的 onStartCommand() 下,根据 command 进行相应的操作。那么我们来看一下 LocalService 的 onStartCommand() 方法:

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@Override
public int onStartCommand(Intent intent, int flags, int startId) {
if (null == intent || !intent.hasExtra(EXTRA_TARGET) || !intent.hasExtra(EXTRA_COMMAND)) {
return START_STICKY;
}
Intent target = intent.getParcelableExtra(EXTRA_TARGET);
int command = intent.getIntExtra(EXTRA_COMMAND, 0);
if (null == target || command <= 0) {
return START_STICKY;
}
ComponentName component = target.getComponent();
LoadedPlugin plugin = mPluginManager.getLoadedPlugin(component);
switch (command) {
case EXTRA_COMMAND_START_SERVICE: {
ActivityThread mainThread = (ActivityThread)ReflectUtil.getActivityThread(getBaseContext());
IApplicationThread appThread = mainThread.getApplicationThread();
Service service;
if (this.mPluginManager.getComponentsHandler().isServiceAvailable(component)) {
service = this.mPluginManager.getComponentsHandler().getService(component);
} else {
try {
service = (Service) plugin.getClassLoader().loadClass(component.getClassName()).newInstance();
Application app = plugin.getApplication();
IBinder token = appThread.asBinder();
Method attach = service.getClass().getMethod("attach", Context.class, ActivityThread.class, String.class, IBinder.class, Application.class, Object.class);
IActivityManager am = mPluginManager.getActivityManager();
attach.invoke(service, plugin.getPluginContext(), mainThread, component.getClassName(), token, app, am);
service.onCreate();
this.mPluginManager.getComponentsHandler().rememberService(component, service);
} catch (Throwable t) {
return START_STICKY;
}
}
service.onStartCommand(target, 0, this.mPluginManager.getComponentsHandler().getServiceCounter(service).getAndIncrement());
break;
}
case EXTRA_COMMAND_BIND_SERVICE: {
ActivityThread mainThread = (ActivityThread)ReflectUtil.getActivityThread(getBaseContext());
IApplicationThread appThread = mainThread.getApplicationThread();
Service service = null;
if (this.mPluginManager.getComponentsHandler().isServiceAvailable(component)) {
service = this.mPluginManager.getComponentsHandler().getService(component);
} else {
try {
service = (Service) plugin.getClassLoader().loadClass(component.getClassName()).newInstance();
Application app = plugin.getApplication();
IBinder token = appThread.asBinder();
Method attach = service.getClass().getMethod("attach", Context.class, ActivityThread.class, String.class, IBinder.class, Application.class, Object.class);
IActivityManager am = mPluginManager.getActivityManager();
attach.invoke(service, plugin.getPluginContext(), mainThread, component.getClassName(), token, app, am);
service.onCreate();
this.mPluginManager.getComponentsHandler().rememberService(component, service);
} catch (Throwable t) {
t.printStackTrace();
}
}
try {
IBinder binder = service.onBind(target);
IBinder serviceConnection = PluginUtil.getBinder(intent.getExtras(), "sc");
IServiceConnection iServiceConnection = IServiceConnection.Stub.asInterface(serviceConnection);
iServiceConnection.connected(component, binder);
} catch (Exception e) {
e.printStackTrace();
}
break;
}
case EXTRA_COMMAND_STOP_SERVICE: {
Service service = this.mPluginManager.getComponentsHandler().forgetService(component);
if (null != service) {
try {
service.onDestroy();
} catch (Exception e) {
Log.e(TAG, "Unable to stop service " + service + ": " + e.toString());
}
} else {
Log.i(TAG, component + " not found");
}
break;
}
case EXTRA_COMMAND_UNBIND_SERVICE: {
Service service = this.mPluginManager.getComponentsHandler().forgetService(component);
if (null != service) {
try {
service.onUnbind(target);
service.onDestroy();
} catch (Exception e) {
Log.e(TAG, "Unable to unbind service " + service + ": " + e.toString());
}
} else {
Log.i(TAG, component + " not found");
}
break;
}
}
return START_STICKY;
}

很显然,在这里面才对应去控制了插件Service的生命周期。具体代码就留给大家分析吧~~

ContentProvider 支持

动态代理 IContentProvider,拦截provider相关的请求,将其中转给Provider Runtime去处理,Provider Runtime会接管系统的所有操作。

我们来看一下 com.didi.virtualapk.internal.PluginContentResolver 这个类:

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public class PluginContentResolver extends ContentResolver {
private ContentResolver mBase;
private PluginManager mPluginManager;
private static Method sAcquireProvider;
private static Method sAcquireExistingProvider;
private static Method sAcquireUnstableProvider;
static {
try {
sAcquireProvider = ContentResolver.class.getDeclaredMethod("acquireProvider",
new Class[]{Context.class, String.class});
sAcquireProvider.setAccessible(true);
sAcquireExistingProvider = ContentResolver.class.getDeclaredMethod("acquireExistingProvider",
new Class[]{Context.class, String.class});
sAcquireExistingProvider.setAccessible(true);
sAcquireUnstableProvider = ContentResolver.class.getDeclaredMethod("acquireUnstableProvider",
new Class[]{Context.class, String.class});
sAcquireUnstableProvider.setAccessible(true);
} catch (Exception e) {
//ignored
}
}
public PluginContentResolver(Context context) {
super(context);
mBase = context.getContentResolver();
mPluginManager = PluginManager.getInstance(context);
}
protected IContentProvider acquireProvider(Context context, String auth) {
try {
if (mPluginManager.resolveContentProvider(auth, 0) != null) {
// 在这里,去 hook 一个 IContentProvider 代理对象
return mPluginManager.getIContentProvider();
}
return (IContentProvider) sAcquireProvider.invoke(mBase, context, auth);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
// ...
}

这个类是在构造 LoadedPlugin 的时候创建的 PluginContext 对象里面的 getContentResolver() 里面创建的。

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class PluginContext extends ContextWrapper {
private final LoadedPlugin mPlugin;
public PluginContext(LoadedPlugin plugin) {
super(plugin.getPluginManager().getHostContext());
this.mPlugin = plugin;
}
@Override
public ContentResolver getContentResolver() {
// 创建代理支持
return new PluginContentResolver(getHostContext());
}
}

那么,上面Hook 的 IContentProvider 代理对象,实际上是在 PluginManager 做的。

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private void hookIContentProviderAsNeeded() {
Uri uri = Uri.parse(PluginContentResolver.getUri(mContext));
mContext.getContentResolver().call(uri, "wakeup", null, null);
try {
Field authority = null;
Field mProvider = null;
ActivityThread activityThread = (ActivityThread) ReflectUtil.getActivityThread(mContext);
Map mProviderMap = (Map) ReflectUtil.getField(activityThread.getClass(), activityThread, "mProviderMap");
Iterator iter = mProviderMap.entrySet().iterator();
while (iter.hasNext()) {
Map.Entry entry = (Map.Entry) iter.next();
Object key = entry.getKey();
Object val = entry.getValue();
String auth;
if (key instanceof String) {
auth = (String) key;
} else {
if (authority == null) {
authority = key.getClass().getDeclaredField("authority");
authority.setAccessible(true);
}
auth = (String) authority.get(key);
}
if (auth.equals(PluginContentResolver.getAuthority(mContext))) {
if (mProvider == null) {
mProvider = val.getClass().getDeclaredField("mProvider");
mProvider.setAccessible(true);
}
IContentProvider rawProvider = (IContentProvider) mProvider.get(val);
IContentProvider proxy = IContentProviderProxy.newInstance(mContext, rawProvider);
mIContentProvider = proxy;
Log.d(TAG, "hookIContentProvider succeed : " + mIContentProvider);
break;
}
}
} catch (Exception e) {
e.printStackTrace();
}
}

这一块的内容,最好根据滴滴提供的Demo,再来看,比较容易理解。

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Uri bookUri = Uri.parse("content://com.ryg.chapter_2.book.provider/book");
ContentValues values = new ContentValues();
values.put("_id", 6);
values.put("name", "程序设计的艺术");

哈哈,作者有点懒,用了任玉刚的《Android开发艺术探索》 改的,被发现了

这里写图片描述

Receiver 支持

官方解释是将插件中静态注册的receiver重新注册一遍。在代码里貌似没找到相应的支持,Demo 里也没有,或许这部分还没完成吧??

小结

本文重点在于分析插件的 Activity 启动流程,其他包括主题、资源,并没有详细分析,因为说细了内容还是有点多了,主要是让大伙儿在阅读代码时,有个大致的方向。有疑问欢迎一起探讨哟~~

感谢阅读!

~沙漠尽头必是绿洲~