?? ? ? ?在前面一篇文章中，我們分析了Android系統(tǒng)在啟動(dòng)時(shí)安裝應(yīng)用程序的過(guò)程，這些應(yīng)用程序安裝好之后，還須要有一個(gè)Home應(yīng)用程序來(lái)負(fù)責(zé)把它們?cè)谧烂嫔险故境鰜?lái)，在Android系統(tǒng)中，這個(gè)默認(rèn)的Home應(yīng)用程序就是Launcher了，本文將詳細(xì)分析Launcher應(yīng)用程序的啟動(dòng)過(guò)程。

?? ? ? ?Android系統(tǒng)的Home應(yīng)用程序Launcher是由ActivityManagerService啟動(dòng)的，而ActivityManagerService和PackageManagerService一樣，都是在開機(jī)時(shí)由SystemServer組件啟動(dòng)的，SystemServer組件首先是啟動(dòng)ePackageManagerServic，由它來(lái)負(fù)責(zé)安裝系統(tǒng)的應(yīng)用程序，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析，系統(tǒng)中的應(yīng)用程序安裝好了以后，SystemServer組件接下來(lái)就要通過(guò)ActivityManagerService來(lái)啟動(dòng)Home應(yīng)用程序Launcher了，Launcher在啟動(dòng)的時(shí)候便會(huì)通過(guò)PackageManagerServic把系統(tǒng)中已經(jīng)安裝好的應(yīng)用程序以快捷圖標(biāo)的形式展示在桌面上，這樣用戶就能夠使用這些應(yīng)用程序了，整個(gè)步驟例如以下圖所看到的：

點(diǎn)擊查看大圖

?? ? ? ?以下詳細(xì)分析每個(gè)步驟。

?? ? ? ?Step 1. SystemServer.main

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/SystemServer.java文件里，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析的Step 1。

?? ? ? ?Step 2.?SystemServer.init1

?? ? ? ?這個(gè)函數(shù)是一個(gè)JNI方法，實(shí)如今?frameworks/base/services/jni/com_android_server_SystemServer.cpp文件里，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析的Step 2。

?? ? ? ?Step 3.?libsystem_server.system_init

?? ? ? ?函數(shù)system_init實(shí)如今libsystem_server庫(kù)中，源碼位于frameworks/base/cmds/system_server/library/system_init.cpp文件里，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析的Step 3。

?? ? ? ?Step 4.?AndroidRuntime.callStatic

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/core/jni/AndroidRuntime.cpp文件里，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析的Step 4。

?? ? ? ?Step 5.?SystemServer.init2

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/SystemServer.java文件里，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析的Step 5。

?? ? ? ?Step 6.?ServerThread.run

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/SystemServer.java文件里，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析的Step 6。

?? ? ? ?Step 7. ActivityManagerService.main

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityManagerServcie.java文件里：

public final class ActivityManagerService extends ActivityManagerNativeimplements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {......public static final Context main(int factoryTest) {AThread thr = new AThread();thr.start();synchronized (thr) {while (thr.mService == null) {try {thr.wait();} catch (InterruptedException e) {}}}ActivityManagerService m = thr.mService;mSelf = m;ActivityThread at = ActivityThread.systemMain();mSystemThread = at;Context context = at.getSystemContext();m.mContext = context;m.mFactoryTest = factoryTest;m.mMainStack = new ActivityStack(m, context, true);m.mBatteryStatsService.publish(context);m.mUsageStatsService.publish(context);synchronized (thr) {thr.mReady = true;thr.notifyAll();}m.startRunning(null, null, null, null);return context;}...... }?? ? ? ?這個(gè)函數(shù)首先通過(guò)AThread線程對(duì)象來(lái)內(nèi)部創(chuàng)建了一個(gè)ActivityManagerService實(shí)例，然后將這個(gè)實(shí)例保存其成員變量mService中，接著又把這個(gè)ActivityManagerService實(shí)例保存在ActivityManagerService類的靜態(tài)成員變量mSelf中，最后初始化其他成員變量，就結(jié)束了。

?? ? ? ?Step 8.?PackageManagerService.main

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/PackageManagerService.java文件里，詳細(xì)能夠參考前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析的Step 7。運(yùn)行完這一步之后，系統(tǒng)中的應(yīng)用程序的全部信息都保存在PackageManagerService中了，后面Home應(yīng)用程序Launcher啟動(dòng)起來(lái)后，就會(huì)把PackageManagerService中的應(yīng)用程序信息取出來(lái)，然后以快捷圖標(biāo)的形式展示在桌面上，后面我們將會(huì)看到這個(gè)過(guò)程。

?? ? ? ?Step 9.?ActivityManagerService.setSystemProcess

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityManagerServcie.java文件里：

public final class ActivityManagerService extends ActivityManagerNativeimplements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {......public static void setSystemProcess() {try {ActivityManagerService m = mSelf;ServiceManager.addService("activity", m);ServiceManager.addService("meminfo", new MemBinder(m));if (MONITOR_CPU_USAGE) {ServiceManager.addService("cpuinfo", new CpuBinder(m));}ServiceManager.addService("permission", new PermissionController(m));ApplicationInfo info =mSelf.mContext.getPackageManager().getApplicationInfo("android", STOCK_PM_FLAGS);mSystemThread.installSystemApplicationInfo(info);synchronized (mSelf) {ProcessRecord app = mSelf.newProcessRecordLocked(mSystemThread.getApplicationThread(), info,info.processName);app.persistent = true;app.pid = MY_PID;app.maxAdj = SYSTEM_ADJ;mSelf.mProcessNames.put(app.processName, app.info.uid, app);synchronized (mSelf.mPidsSelfLocked) {mSelf.mPidsSelfLocked.put(app.pid, app);}mSelf.updateLruProcessLocked(app, true, true);}} catch (PackageManager.NameNotFoundException e) {throw new RuntimeException("Unable to find android system package", e);}}...... }?? ? ? ?這個(gè)函數(shù)首先是將這個(gè)ActivityManagerService實(shí)例加入到ServiceManager中去托管，這樣其他地方就能夠通過(guò)ServiceManager.getService接口來(lái)訪問這個(gè)全局唯一的ActivityManagerService實(shí)例了，接著又通過(guò)調(diào)用mSystemThread.installSystemApplicationInfo函數(shù)來(lái)把應(yīng)用程序框架層以下的android包載入進(jìn)來(lái) ，這里的mSystemThread是一個(gè)ActivityThread類型的實(shí)例變量，它是在上面的Step 7中創(chuàng)建的，后面就是一些其他的初始化工作了。

?? ? ? ?Step 10. ?ActivityManagerService.systemReady

?? ? ? ?這個(gè)函數(shù)是在上面的Step 6中的ServerThread.run函數(shù)在將系統(tǒng)中的一系列服務(wù)都初始化完成之后才調(diào)用的，它定義在frameworks/base/services/java/com/android/server/am/ActivityManagerServcie.java文件里：

public final class ActivityManagerService extends ActivityManagerNativeimplements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {......public void systemReady(final Runnable goingCallback) {......synchronized (this) {......mMainStack.resumeTopActivityLocked(null);}}...... }?? ? ? ?這個(gè)函數(shù)的內(nèi)容比較多，這里省去無(wú)關(guān)的部分，主要關(guān)心啟動(dòng)Home應(yīng)用程序的邏輯，這里就是通過(guò)mMainStack.resumeTopActivityLocked函數(shù)來(lái)啟動(dòng)Home應(yīng)用程序的了，這里的mMainStack是一個(gè)ActivityStack類型的實(shí)例變量。

?? ? ? ?Step 11. ActivityStack.resumeTopActivityLocked

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityStack.java文件里：

public class ActivityStack {......final boolean resumeTopActivityLocked(ActivityRecord prev) {// Find the first activity that is not finishing.ActivityRecord next = topRunningActivityLocked(null);......if (next == null) {// There are no more activities! Let's just start up the// Launcher...if (mMainStack) {return mService.startHomeActivityLocked();}}......}...... }?? ? ? ?這里調(diào)用函數(shù)topRunningActivityLocked返回的是當(dāng)前系統(tǒng)Activity堆棧最頂端的Activity，因?yàn)榇藭r(shí)還沒有Activity被啟動(dòng)過(guò)，因此，返回值為null，即next變量的值為null，于是就調(diào)用mService.startHomeActivityLocked語(yǔ)句，這里的mService就是前面在Step 7中創(chuàng)建的ActivityManagerService實(shí)例了。

?? ? ? ?Step 12.?ActivityManagerService.startHomeActivityLocked

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityManagerServcie.java文件里：

public final class ActivityManagerService extends ActivityManagerNativeimplements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {......boolean startHomeActivityLocked() {......Intent intent = new Intent(mTopAction,mTopData != null ? Uri.parse(mTopData) : null);intent.setComponent(mTopComponent);if (mFactoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL) {intent.addCategory(Intent.CATEGORY_HOME);}ActivityInfo aInfo =intent.resolveActivityInfo(mContext.getPackageManager(),STOCK_PM_FLAGS);if (aInfo != null) {intent.setComponent(new ComponentName(aInfo.applicationInfo.packageName, aInfo.name));// Don't do this if the home app is currently being// instrumented.ProcessRecord app = getProcessRecordLocked(aInfo.processName,aInfo.applicationInfo.uid);if (app == null || app.instrumentationClass == null) {intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);mMainStack.startActivityLocked(null, intent, null, null, 0, aInfo,null, null, 0, 0, 0, false, false);}}return true;}...... }?? ? ? ?函數(shù)首先創(chuàng)建一個(gè)CATEGORY_HOME類型的Intent，然后通過(guò)Intent.resolveActivityInfo函數(shù)向PackageManagerService查詢Category類型為HOME的Activity，這里我們?nèi)绻麅H僅有系統(tǒng)自帶的Launcher應(yīng)用程序注冊(cè)了HOME類型的Activity（見packages/apps/Launcher2/AndroidManifest.xml文件）：

<manifestxmlns:android="http://schemas.android.com/apk/res/android"package="com.android.launcher"android:sharedUserId="@string/sharedUserId">......<applicationandroid:name="com.android.launcher2.LauncherApplication"android:process="@string/process"android:label="@string/application_name"android:icon="@drawable/ic_launcher_home"><activityandroid:name="com.android.launcher2.Launcher"android:launchMode="singleTask"android:clearTaskOnLaunch="true"android:stateNotNeeded="true"android:theme="@style/Theme"android:screenOrientation="nosensor"android:windowSoftInputMode="stateUnspecified|adjustPan"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.HOME" /><category android:name="android.intent.category.DEFAULT" /><category android:name="android.intent.category.MONKEY"/></intent-filter></activity>......</application> </manifest>

?? ? ? ?因此，這里就返回com.android.launcher2.Launcher這個(gè)Activity了。因?yàn)槭堑谝淮螁?dòng)這個(gè)Activity，接下來(lái)調(diào)用函數(shù)getProcessRecordLocked返回來(lái)的ProcessRecord值為null，于是，就調(diào)用mMainStack.startActivityLocked函數(shù)啟動(dòng)com.android.launcher2.Launcher這個(gè)Activity了，這里的mMainStack是一個(gè)ActivityStack類型的成員變量。

?? ? ? ?Step 13. ?ActivityStack.startActivityLocked

?? ? ? ?這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityStack.java文件里，詳細(xì)能夠參考Android應(yīng)用程序啟動(dòng)過(guò)程源碼分析一文，這里就不詳述了，在我們這個(gè)場(chǎng)景中，調(diào)用這個(gè)函數(shù)的最后結(jié)果就是把com.android.launcher2.Launcher啟動(dòng)起來(lái)，接著調(diào)用它的onCreate函數(shù)。

?? ? ? ?Step 14.?Launcher.onCreate

?? ? ? ?這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/Launcher.java文件里：

public final class Launcher extends Activityimplements View.OnClickListener, OnLongClickListener, LauncherModel.Callbacks, AllAppsView.Watcher {......@Overrideprotected void onCreate(Bundle savedInstanceState) {......if (!mRestoring) {mModel.startLoader(this, true);}......}...... }?? ? ? ?這里的mModel是一個(gè)LauncherModel類型的成員變量，這里通過(guò)調(diào)用它的startLoader成員函數(shù)來(lái)運(yùn)行加應(yīng)用程序的操作。

?? ? ? ?Step 15.?LauncherModel.startLoader

?? ? ? ?這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/LauncherModel.java文件里：

public class LauncherModel extends BroadcastReceiver {......public void startLoader(Context context, boolean isLaunching) {......synchronized (mLock) {......// Don't bother to start the thread if we know it's not going to do anythingif (mCallbacks != null && mCallbacks.get() != null) {// If there is already one running, tell it to stop.LoaderTask oldTask = mLoaderTask;if (oldTask != null) {if (oldTask.isLaunching()) {// don't downgrade isLaunching if we're already runningisLaunching = true;}oldTask.stopLocked();}mLoaderTask = new LoaderTask(context, isLaunching);sWorker.post(mLoaderTask);}}}...... }?? ? ? ?這里不是直接載入應(yīng)用程序，而是把載入應(yīng)用程序的操作作為一個(gè)消息來(lái)處理。這里的sWorker是一個(gè)Handler，通過(guò)它的post方式把一個(gè)消息放在消息隊(duì)列中去，然后系統(tǒng)就會(huì)調(diào)用傳進(jìn)去的參數(shù)mLoaderTask的run函數(shù)來(lái)處理這個(gè)消息，這個(gè)mLoaderTask是LoaderTask類型的實(shí)例，于是，以下就會(huì)運(yùn)行LoaderTask類的run函數(shù)了。

?? ? ? ?Step 16. LoaderTask.run

?? ? ? ?這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/LauncherModel.java文件里：

public class LauncherModel extends BroadcastReceiver {......private class LoaderTask implements Runnable {......public void run() {......keep_running: {......// second stepif (loadWorkspaceFirst) {......loadAndBindAllApps();} else {......}......}......}......}...... }?? ? ? ?這里調(diào)用loadAndBindAllApps成員函數(shù)來(lái)進(jìn)一步操作。

?? ? ? ?Step 17.?LoaderTask.loadAndBindAllApps
?? ? ? ?這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/LauncherModel.java文件里：

public class LauncherModel extends BroadcastReceiver {......private class LoaderTask implements Runnable {......private void loadAndBindAllApps() {......if (!mAllAppsLoaded) {loadAllAppsByBatch();if (mStopped) {return;}mAllAppsLoaded = true;} else {onlyBindAllApps();}}......}...... }?? ? ? ?因?yàn)檫€沒有載入過(guò)應(yīng)用程序，這里的mAllAppsLoaded為false，于是就繼續(xù)調(diào)用loadAllAppsByBatch函數(shù)來(lái)進(jìn)一步操作了。

?? ? ? ?Step 18.?LoaderTask.loadAllAppsByBatch
?? ? ? ?這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/LauncherModel.java文件里：

public class LauncherModel extends BroadcastReceiver {......private class LoaderTask implements Runnable {......private void loadAllAppsByBatch() { ......final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);final PackageManager packageManager = mContext.getPackageManager();List<ResolveInfo> apps = null;int N = Integer.MAX_VALUE;int startIndex;int i=0;int batchSize = -1;while (i < N && !mStopped) {if (i == 0) {mAllAppsList.clear();......apps = packageManager.queryIntentActivities(mainIntent, 0);......N = apps.size();......if (mBatchSize == 0) {batchSize = N;} else {batchSize = mBatchSize;}......Collections.sort(apps,new ResolveInfo.DisplayNameComparator(packageManager));}startIndex = i;for (int j=0; i<N && j<batchSize; j++) {// This builds the icon bitmaps.mAllAppsList.add(new ApplicationInfo(apps.get(i), mIconCache));i++;}final boolean first = i <= batchSize;final Callbacks callbacks = tryGetCallbacks(oldCallbacks);final ArrayList<ApplicationInfo> added = mAllAppsList.added;mAllAppsList.added = new ArrayList<ApplicationInfo>();mHandler.post(new Runnable() {public void run() {final long t = SystemClock.uptimeMillis();if (callbacks != null) {if (first) {callbacks.bindAllApplications(added);} else {callbacks.bindAppsAdded(added);}......} else {......}}});......}......}......}...... }?? ? ? ?函數(shù)首先構(gòu)造一個(gè)CATEGORY_LAUNCHER類型的Intent：

final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);?? ? ? ?接著從mContext變量中獲得PackageManagerService的接口：

final PackageManager packageManager = mContext.getPackageManager();

?? ? ? 下一步就是通過(guò)這個(gè)PackageManagerService.queryIntentActivities接口來(lái)取回全部Action類型為Intent.ACTION_MAIN，而且Category類型為Intent.CATEGORY_LAUNCHER的Activity了。

?? ? ? 我們先進(jìn)入到PackageManagerService.queryIntentActivities函數(shù)中看看是怎樣獲得這些Activity的，然后再回到這個(gè)函數(shù)中來(lái)看其余操作。

?? ? ? Step 19.?PackageManagerService.queryIntentActivities

?? ? ? 這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/PackageManagerService.java文件里：

class PackageManagerService extends IPackageManager.Stub {......public List<ResolveInfo> queryIntentActivities(Intent intent,String resolvedType, int flags) {......synchronized (mPackages) {String pkgName = intent.getPackage();if (pkgName == null) {return (List<ResolveInfo>)mActivities.queryIntent(intent,resolvedType, flags);}......}......}...... }

?? ? ? ?回顧前面一篇文章Android應(yīng)用程序安裝過(guò)程源碼分析，系統(tǒng)在前面的Step 8中啟動(dòng)PackageManagerService時(shí)，會(huì)把系統(tǒng)中的應(yīng)用程序都解析一遍，然后把解析得到的Activity都保存在mActivities變量中，這里通過(guò)這個(gè)mActivities變量的queryIntent函數(shù)返回符合條件intent的Activity，這里要返回的便是Action類型為Intent.ACTION_MAIN，而且Category類型為Intent.CATEGORY_LAUNCHER的Activity了。

?? ? ? ?回到Step 18中的?LoaderTask.loadAllAppsByBatch函數(shù)中，從queryIntentActivities函數(shù)調(diào)用處返回所要求的Activity后，便調(diào)用函數(shù)tryGetCallbacks(oldCallbacks)得到一個(gè)返CallBack接口，這個(gè)接口是由Launcher類實(shí)現(xiàn)的，接著調(diào)用這個(gè)接口的.bindAllApplications函數(shù)來(lái)進(jìn)一步操作。注意，這里又是通過(guò)消息來(lái)處理載入應(yīng)用程序的操作的。

?? ? ? ?Step 20.?Launcher.bindAllApplications

?? ? ? ?這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/Launcher.java文件里：

public final class Launcher extends Activityimplements View.OnClickListener, OnLongClickListener, LauncherModel.Callbacks, AllAppsView.Watcher {......private AllAppsView mAllAppsGrid;......public void bindAllApplications(ArrayList<ApplicationInfo> apps) {mAllAppsGrid.setApps(apps);}...... }?? ? ? ?這里的mAllAppsGrid是一個(gè)AllAppsView類型的變量，它的實(shí)際類型一般就是AllApps2D了。

?? ? ? ?Step 21.?AllApps2D.setApps

?? ? ? ?這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/AllApps2D.java文件里：

public class AllApps2Dextends RelativeLayoutimplements AllAppsView,AdapterView.OnItemClickListener,AdapterView.OnItemLongClickListener,View.OnKeyListener,DragSource {......public void setApps(ArrayList<ApplicationInfo> list) {mAllAppsList.clear();addApps(list);}public void addApps(ArrayList<ApplicationInfo> list) {final int N = list.size();for (int i=0; i<N; i++) {final ApplicationInfo item = list.get(i);int index = Collections.binarySearch(mAllAppsList, item,LauncherModel.APP_NAME_COMPARATOR);if (index < 0) {index = -(index+1);}mAllAppsList.add(index, item);}mAppsAdapter.notifyDataSetChanged();}...... }?? ? ? ?函數(shù)setApps首先清空mAllAppsList列表，然后調(diào)用addApps函數(shù)來(lái)為上一步得到的每個(gè)應(yīng)用程序創(chuàng)建一個(gè)ApplicationInfo實(shí)例了，有了這些ApplicationInfo實(shí)例之后，就能夠在桌面上展示系統(tǒng)中全部的應(yīng)用程序了。

?? ? ? ?到了這里，系統(tǒng)默認(rèn)的Home應(yīng)用程序Launcher就把PackageManagerService中的應(yīng)用程序載入進(jìn)來(lái)了，當(dāng)我們?cè)谄聊簧宵c(diǎn)擊以下這個(gè)圖標(biāo)時(shí)，就會(huì)把剛才載入好的應(yīng)用程序以圖標(biāo)的形式展示出來(lái)了：

?? ? ? ?點(diǎn)擊這個(gè)button時(shí)，便會(huì)響應(yīng)Launcher.onClick函數(shù)：

public final class Launcher extends Activityimplements View.OnClickListener, OnLongClickListener, LauncherModel.Callbacks, AllAppsView.Watcher {......public void onClick(View v) {Object tag = v.getTag();if (tag instanceof ShortcutInfo) {......} else if (tag instanceof FolderInfo) {......} else if (v == mHandleView) {if (isAllAppsVisible()) {......} else {showAllApps(true);}}}...... }?? ? ? ?接著就會(huì)調(diào)用showAllApps函數(shù)顯示應(yīng)用程序圖標(biāo)：

public final class Launcher extends Activityimplements View.OnClickListener, OnLongClickListener, LauncherModel.Callbacks, AllAppsView.Watcher {......void showAllApps(boolean animated) {mAllAppsGrid.zoom(1.0f, animated);((View) mAllAppsGrid).setFocusable(true);((View) mAllAppsGrid).requestFocus();// TODO: fade these two toomDeleteZone.setVisibility(View.GONE);}...... }?? ? ? ?這樣我們就能夠看到系統(tǒng)中的應(yīng)用程序了：

?? ? ? ?當(dāng)點(diǎn)擊上面的這些應(yīng)用程序圖標(biāo)時(shí)，便會(huì)響應(yīng)AllApps2D.onItemClick函數(shù)：

public class AllApps2Dextends RelativeLayoutimplements AllAppsView,AdapterView.OnItemClickListener,AdapterView.OnItemLongClickListener,View.OnKeyListener,DragSource {......public void onItemClick(AdapterView parent, View v, int position, long id) {ApplicationInfo app = (ApplicationInfo) parent.getItemAtPosition(position);mLauncher.startActivitySafely(app.intent, app);}...... }

?? ? ? ?這里的成員變量mLauncher的類型為L(zhǎng)auncher，于是就調(diào)用Launcher.startActivitySafely函數(shù)來(lái)啟動(dòng)應(yīng)用程序了，這個(gè)過(guò)程詳細(xì)能夠參考Android應(yīng)用程序啟動(dòng)過(guò)程源碼分析一文。

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