本系列主要介紹Android8.0系統(tǒng)啟動過程中涉及到的init妓柜、Zygote箱季、SystemServer和Launcher。
在之前的三篇文章中棍掐，講解了如下的過程：
- 初始化化：電源上電藏雏，加載BootLoader程序； 啟動init.cpp作煌，解析init.rc配置文件掘殴；
- 啟動Zygote進(jìn)程：啟動虛擬機(jī)和注冊JNI方法赚瘦；注冊Socket服務(wù)端，預(yù)加載資源奏寨；執(zhí)行runSelectLoop(）方法等待其他進(jìn)程的注冊起意；
- 啟動SystemServer進(jìn)程：通過Zygote啟動，創(chuàng)建Binder線程池病瞳、執(zhí)行main方法揽咕；開啟 三個(gè)系統(tǒng)服務(wù)（引導(dǎo)、核心和其他）套菜。
在完成以上三個(gè)過程后心褐，我們的系統(tǒng)就開始加載Launcher應(yīng)用，查看源碼可以發(fā)現(xiàn)Launcher是作為一個(gè)APP應(yīng)用執(zhí)行的笼踩，其一般位于系統(tǒng)的packages/apps目錄下逗爹，可以通過該應(yīng)用啟動系統(tǒng)中其他應(yīng)用程序，提供快捷訪問圖標(biāo)嚎于。
一掘而、Launcher的啟動
在這里插入圖片描述
1.1啟動準(zhǔn)備
在SystemServer啟動時(shí)，會先啟動引導(dǎo)服務(wù)于购，其中包括PMS（PackageManagerService）和AMS(ActivityManagerService)袍睡，其中PMS主要作用是系統(tǒng)中的APK的解析和安裝；AMS主要用于四大組件的啟動 和管理肋僧，因此LauncherActivity通過AMS啟動斑胜。
完成引導(dǎo)服務(wù)的啟動后，開啟啟動其他服務(wù)嫌吠。啟動Launcher的入口為AMS的systemReady方法止潘，
frameworks\base\services\java\com\android\server\SystemServer.java
private void startOtherServices() {
...
//在此之前會做大量的準(zhǔn)備工作，包括AMS辫诅、PMS 和NetworkScoreService等各種服務(wù)凭戴，完成以上操作后，表示activity manager可以運(yùn)行
mActivityManagerService.systemReady(() -> {
Slog.i(TAG, "Making services ready");
traceBeginAndSlog("StartActivityManagerReadyPhase");
mSystemServiceManager.startBootPhase(
SystemService.PHASE_ACTIVITY_MANAGER_READY);
...
}
...
...
}
frameworks\base\services\core\java\com\android\server\am\ActivityManagerService.java
public void systemReady(final Runnable goingCallback, TimingsTraceLog traceLog) {
traceLog.traceBegin("PhaseActivityManagerReady");
synchronized(this) {
...
mStackSupervisor.resumeFocusedStackTopActivityLocked();
mUserController.sendUserSwitchBroadcastsLocked(-1, currentUserId);
...
}
}
1.2找到Launcher 的Activity
AMS通過調(diào)用ActivityStack實(shí)現(xiàn)對堆棧中Activity對象的管理炕矮，我們的最終目的是查找到Launcher應(yīng)用所在的Activity是如何被調(diào)用起來的么夫？
其流程如下：
ActivityStackSuperior#resumeFocusedStackTopActivityLocked() ->ActivityStack#resumeTopActivityUncheckedLocked()->resumeTopActivityInnerLocked()
在resumeTopActivityInnerLocked中，通過調(diào)用startHomeActivityLocked方法肤视，開啟啟動Launcher的Activty档痪。
frameworks\base\services\core\java\com\android\server\am\ActivityStackSupervisor.java
boolean resumeFocusedStackTopActivityLocked(
ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
if (targetStack != null && isFocusedStack(targetStack)) {
return targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
}
...
return false;
frameworks\base\services\core\java\com\android\server\am\ActivityStack.java
boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
if (mStackSupervisor.inResumeTopActivity) {
return false;
}
boolean result = false;
try {
mStackSupervisor.inResumeTopActivity = true;
result = resumeTopActivityInnerLocked(prev, options);
} finally {
mStackSupervisor.inResumeTopActivity = false;
}
final ActivityRecord next = topRunningActivityLocked(true /* focusableOnly */);
if (next == null || !next.canTurnScreenOn()) {
checkReadyForSleep();
}
return result;
}
frameworks\base\services\core\java\com\android\server\am\ActivityStackSupervisor.java
private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
...
return isOnHomeDisplay() &&
mStackSupervisor.resumeHomeStackTask(prev, reason);
...
if (r != null && !r.finishing) {
moveFocusableActivityStackToFrontLocked(r, myReason);
return resumeFocusedStackTopActivityLocked(mHomeStack, prev, null);
}
return mService.startHomeActivityLocked(mCurrentUser, myReason);
...
}
1.3 啟動Launcher
frameworks\base\services\core\java\com\android\server\am\ActivityManagerService.java
boolean startHomeActivityLocked(int userId, String reason) {
//1 判斷工廠模式和topAction
if (mFactoryTest == FactoryTest.FACTORY_TEST_LOW_LEVEL
&& mTopAction == null) {
return false;
}
//2 創(chuàng)建啟動Launcher的Intent
Intent intent = getHomeIntent();
ActivityInfo aInfo = resolveActivityInfo(intent, STOCK_PM_FLAGS, userId);
if (aInfo != null) {
intent.setComponent(new ComponentName(aInfo.applicationInfo.packageName, aInfo.name));
aInfo = new ActivityInfo(aInfo);
aInfo.applicationInfo = getAppInfoForUser(aInfo.applicationInfo, userId);
ProcessRecord app = getProcessRecordLocked(aInfo.processName,
aInfo.applicationInfo.uid, true);
if (app == null || app.instr == null) {
intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
final int resolvedUserId = UserHandle.getUserId(aInfo.applicationInfo.uid);
final String myReason = reason + ":" + userId + ":" + resolvedUserId;
//3 啟動Launcdr
mActivityStarter.startHomeActivityLocked(intent, aInfo, myReason);
}
} else {
Slog.wtf(TAG, "No home screen found for " + intent, new Throwable());
}
return true;
}
在注釋1處是對運(yùn)行模式和Action的判斷，其中運(yùn)行模式包括：非工廠模式邢滑、低級工廠模式和高級工廠模式腐螟。而Action的是是指啟動該Intent的Action，默認(rèn)是Intent.ACTION_MAIN，表示是該應(yīng)用的第一個(gè)啟動的Activity遭垛，一般在創(chuàng)建應(yīng)用時(shí)尼桶，AndroidMainfest.xm中都會包含唯一個(gè)該標(biāo)簽的Action操灿。
而對于桌面應(yīng)用锯仪，會增加Intent.HOME的標(biāo)簽，如果我們想自定義桌面應(yīng)用趾盐，可在該應(yīng)用的AndroidMainfest中的啟動Activity的Action添加android.Intent.action.HOME庶喜，如下所示：
<application
...
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.HOME"/>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
啟動Launer是在ActivityStarter的startHomeActivityLocked方法中完成，通過ActivityStackSupervisor將該Intent移動至HomeStack(用于存儲Launcher的變量)的頂部救鲤，最終調(diào)用startActivityLocked方法啟動該Intnet久窟，實(shí)現(xiàn)對Launcer的啟動。
void startHomeActivityLocked(Intent intent, ActivityInfo aInfo, String reason) {
mSupervisor.moveHomeStackTaskToTop(reason);
...
}
二 本缠、Launcher桌面圖標(biāo)顯示
完成Launcer的啟動后斥扛，作為一個(gè)獨(dú)立的APP，Launcher開始執(zhí)行應(yīng)用的加載和桌面圖標(biāo)的顯示丹锹。
在這里插入圖片描述
2.1 加載APP
packages\apps\Launcher3\src\com\android\launcher3\Launcher.java
protected void onCreate(Bundle savedInstanceState) {
...
//加載桌面顏色信息和監(jiān)聽主題變化
WallpaperColorInfo wallpaperColorInfo = WallpaperColorInfo.getInstance(this);
wallpaperColorInfo.setOnThemeChangeListener(this);
...
//加載桌面應(yīng)用信息
LauncherAppState app = LauncherAppState.getInstance(this);
...
mModel = app.setLauncher(this);
...
//加載和設(shè)置桌面view
mLauncherView = LayoutInflater.from(this).inflate(R.layout.launcher, null);
setupViews();
...
if (!mModel.startLoader(currentScreen)) {
mDragLayer.setAlpha(0);
} else {
mWorkspace.setCurrentPage(currentScreen);
setWorkspaceLoading(true);
}
}
//設(shè)置launcher的監(jiān)聽稀颁，初始化model
packages\apps\Launcher3\src\com\android\launcher3\LauncherAppState
LauncherModel setLauncher(Launcher launcher) {
getLocalProvider(mContext).setLauncherProviderChangeListener(launcher);
mModel.initialize(launcher); //傳入Launcher對象
return mModel;
}
在設(shè)置監(jiān)聽時(shí)，傳入的Callbacks 對象時(shí)Launcher楣黍，是為了在APP加載完成時(shí)匾灶，方便通過接口回調(diào)的形式返回值Launcher，
下面開始加載App租漂。
packages\apps\Launcher3\src\com\android\launcher3\LauncherModel
public void initialize(Callbacks callbacks) {
synchronized (mLock) {
Preconditions.assertUIThread();
mCallbacks = new WeakReference<>(callbacks);
}
}
//Callbacks 接口包含的內(nèi)容如下阶女，主要用到bindAllApplications
public interface Callbacks extends LauncherAppWidgetHost.ProviderChangedListener {
...
public void bindAllApplications(ArrayList<AppInfo> apps);
public void bindAppsAddedOrUpdated(ArrayList<AppInfo> apps);
public void bindAppsAdded(ArrayList<Long> newScreens,
ArrayList<ItemInfo> addNotAnimated,
ArrayList<ItemInfo> addAnimated);
public void bindPromiseAppProgressUpdated(PromiseAppInfo app);
public void bindShortcutsChanged(ArrayList<ShortcutInfo> updated, UserHandle user);
public void bindWidgetsRestored(ArrayList<LauncherAppWidgetInfo> widgets);
public void bindRestoreItemsChange(HashSet<ItemInfo> updates);
public void bindWorkspaceComponentsRemoved(ItemInfoMatcher matcher);
public void bindAppInfosRemoved(ArrayList<AppInfo> appInfos);
public void bindAllWidgets(MultiHashMap<PackageItemInfo, WidgetItem> widgets);
...
}
加載的Task分析如下
...
packages\apps\Launcher3\src\com\android\launcher3\LauncherModel
//開始加載
public boolean startLoader(int synchronousBindPage) {
...
synchronized (mLock) {
//清除之前的回調(diào)緩存
if (mCallbacks != null && mCallbacks.get() != null) {
final Callbacks oldCallbacks = mCallbacks.get();
// Clear any pending bind-runnables from the synchronized load process.
mUiExecutor.execute(new Runnable() {
public void run() {
oldCallbacks.clearPendingBinds();
}
});
// If there is already one running, tell it to stop.
stopLoader();
LoaderResults loaderResults = new LoaderResults(mApp, sBgDataModel,
mBgAllAppsList, synchronousBindPage, mCallbacks);//包含Callbacks對象
if (mModelLoaded && !mIsLoaderTaskRunning) { //已經(jīng)加載完成且沒有正在加載
//加載完成后，開始將結(jié)果回調(diào)至Launcher
loaderResults.bindWorkspace();
loaderResults.bindAllApps(); //加載的回調(diào)
loaderResults.bindDeepShortcuts();
loaderResults.bindWidgets();
return true;
} else {
//開始不斷的加載 工作區(qū)間哩治、所有的APP秃踩、快捷圖標(biāo)和抽屜控件
startLoaderForResults(loaderResults);
}
}
}
return false;
}
packages\apps\Launcher3\src\com\android\launcher3\LauncherModel
public void startLoaderForResults(LoaderResults results) {
synchronized (mLock) {
//停止加載
stopLoader();
//創(chuàng)建新的加載task
mLoaderTask = new LoaderTask(mApp, mBgAllAppsList, sBgDataModel, results);
//在WorkerThread中執(zhí)行該task
runOnWorkerThread(mLoaderTask);
}
}
//加載中涉及的線程初始化
packages\apps\Launcher3\src\com\android\launcher3\LauncherModel
@Thunk static final HandlerThread sWorkerThread = new HandlerThread("launcher-loader");
static {
sWorkerThread.start();
}
@Thunk static final Handler sWorker = new Handler(sWorkerThread.getLooper());
2.2 加載回調(diào)處理
通過LauncherModel的加載線程，獲取到了系統(tǒng)中所有的apps的信息业筏，同時(shí)通過其Callbacks的接口吞瞪，很方便的將結(jié)果傳遞出去，
packages\apps\Launcher3\src\com\android\launcher3\Launcher.java
public void bindAllApplications(final ArrayList<AppInfo> apps) {
Runnable r = new RunnableWithId(RUNNABLE_ID_BIND_APPS) {
public void run() {
bindAllApplications(apps);
}
};
...
//加載完成后AllAppsContainerView數(shù)據(jù)更新
mAppsView.setApps(apps);
}
if (mLauncherCallbacks != null) {
mLauncherCallbacks.bindAllApplications(apps);
}
}
數(shù)據(jù)回調(diào)值Launcher的bindAllApplications驾孔，開始對AllAppsContainerView界面進(jìn)行數(shù)據(jù)設(shè)置芍秆，其設(shè)置的控制控件為AlphabeticalAppsList，通過調(diào)用AlphabeticalAppsList實(shí)現(xiàn)對數(shù)據(jù)的設(shè)置處理翠勉，其實(shí)現(xiàn)流程和Recycleview的設(shè)置比較類似妖啥。
packages\apps\Launcher3\src\com\android\launcher3\allapps\AllAppsContainerView.java
public void setApps(List<AppInfo> apps) {
mApps.setApps(apps);
}
//數(shù)據(jù)傳遞控制控件中
packages\apps\Launcher3\src\com\android\launcher3\allapps\AlphabeticalAppsList.java
public void setApps(List<AppInfo> apps) {
mComponentToAppMap.clear();
addOrUpdateApps(apps);
}
packages\apps\Launcher3\src\com\android\launcher3\allapps\AllAppsContainerView.java
@Override
protected void onFinishInflate() {
...
mAppsRecyclerView = findViewById(R.id.apps_list_view); //可以看到桌面應(yīng)用部分的界面為RecyclerView
mAppsRecyclerView.setApps(mApps);
mAppsRecyclerView.setLayoutManager(mLayoutManager);
mAppsRecyclerView.setAdapter(mAdapter);
mAppsRecyclerView.setHasFixedSize(true);
...
}
AllAppsContainerView會在XML布局文件加載完成后，調(diào)用onFinishInflate方法对碌，使加載的數(shù)據(jù)最終顯示在桌面上荆虱。形成我們看到的桌面圖標(biāo)。
2.3 點(diǎn)擊桌面圖標(biāo)的跳轉(zhuǎn)至應(yīng)用
在AllAppsContainerView設(shè)置adapter后，由于RecyclerView不包含setOnItemClickListener方法怀读，因此一般是在Adapter中自定義實(shí)現(xiàn)诉位，可通過回調(diào)的形式將點(diǎn)擊事件傳遞出去，Launcher的執(zhí)行流程如下：
//packages\apps\Launcher3\src\com\android\launcher3\allapps\AllAppsContainerView.java
public AllAppsContainerView(Context context, AttributeSet attrs, int defStyleAttr) {
...
//創(chuàng)建新的Adapter
mAdapter = new AllAppsGridAdapter(mLauncher, mApps, mLauncher, this);
mSpringAnimationHandler = mAdapter.getSpringAnimationHandler();
mApps.setAdapter(mAdapter);
...
}
設(shè)置點(diǎn)擊的監(jiān)聽回調(diào)
//packages\apps\Launcher3\src\com\android\launcher3\allapps\AllAppsGridAdapter.java
public AllAppsGridAdapter(Launcher launcher, AlphabeticalAppsList apps, View.OnClickListener
iconClickListener, View.OnLongClickListener iconLongClickListener) {
...
mIconClickListener = iconClickListener;
...
}
點(diǎn)擊事件的處理
packages\apps\Launcher3\src\com\android\launcher3\Launcher.java
public void onClick(View v) {
...
Object tag = v.getTag();
if (tag instanceof ShortcutInfo) {
onClickAppShortcut(v);
} else if (tag instanceof FolderInfo) {
if (v instanceof FolderIcon) {
onClickFolderIcon(v);
}
} else if ((v instanceof PageIndicator) ||
(v == mAllAppsButton && mAllAppsButton != null)) {
onClickAllAppsButton(v);
} else if (tag instanceof AppInfo) {
startAppShortcutOrInfoActivity(v);
} else if (tag instanceof LauncherAppWidgetInfo) {
if (v instanceof PendingAppWidgetHostView) {
onClickPendingWidget((PendingAppWidgetHostView) v);
}
}
}
//點(diǎn)擊桌面應(yīng)用的快捷圖標(biāo)的處理
protected void onClickAppShortcut(final View v) {
...
startAppShortcutOrInfoActivity(v);
...
}
private void startAppShortcutOrInfoActivity(View v) {
ItemInfo item = (ItemInfo) v.getTag();
Intent intent;
if (item instanceof PromiseAppInfo) {
PromiseAppInfo promiseAppInfo = (PromiseAppInfo) item;
intent = promiseAppInfo.getMarketIntent();
} else {
intent = item.getIntent();
}
...
//跳轉(zhuǎn)至相應(yīng)的應(yīng)用
boolean success = startActivitySafely(v, intent, item);
...
}
至此Launcher的啟動過程便分析完菜枷，總結(jié)如下：
- 啟動：SystemServer啟動PMS和AMS苍糠，通過AMS的systemReady開始加載；
- 查找：查找流程如下ActivityStackSuperior#resumeFocusedStackTopActivityLocked() ->ActivityStack#resumeTopActivityUncheckedLocked()->resumeTopActivityInnerLocked()啤誊；
- 顯示：在resumeTopActivityInnerLocked中通過調(diào)用startHomeActivityLocked方法岳瞭，啟動Launcher的Activty，通過LauncherModel的加載線程處理蚊锹，獲取到所有的Apps信息瞳筏，借助Callbacks的接口回調(diào)的形式將數(shù)據(jù)返回值Launcher，然后將數(shù)據(jù)賦值給AllAppsContainerView牡昆，使Apps的桌面圖標(biāo)顯示至桌面中姚炕。
- 跳轉(zhuǎn)：通過設(shè)置點(diǎn)擊事件的回調(diào)處理，點(diǎn)擊桌面圖標(biāo)后丢烘，通過startActivitySafely跳轉(zhuǎn)至應(yīng)用的Main界面柱宦。
