? ? 最近研究ICS4.0的Launcher，發現4.0和2.3有稍微點區別，但是區別不是特別大，所以我就先整理一下Launcher啟動的大致流程。 Launcher其實是貫徹于手機的整個系統的，時時刻刻都在運行，要是Launcher不運行了，手機就得黑屏了。Launcher的 LauncherMode=singletask，所以說不管Launcher啟動了哪個應用，總有個Launcher的實例在堆棧中，并且位于棧底。點 擊Home鍵進入到Launcher，上篇Android的全局鍵（home鍵/長按耳機鍵）詳解【android源碼解析八】?中有詳細的介紹。大致思路其實就是啟動launcher的時候，新啟動一個task。大致先說這么多，先看截圖：
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?????????????????????????????????????????????????????????????????????????? 圖（1）
????? 上圖是4.0的Launcher界面，下面我們分步來解析一下Launcher的啟動過程。
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???? Step 0：首先要給大家介紹一下Launcher的數據庫，這個數據庫中存放著待機界面的圖標，主屏底部的應用程序圖標和桌面folder中各應用程序的圖 標，ICS4.0的folder中只能放應用程序的快捷方式，shortcut不能放到這個folder中，先看截圖：?
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??????????????????????????????????????????????????????????????????????? 圖（2）
????? ?說說各字段的含義：
??????????????? title：表示桌面應用程序的名字，有的title為空，表示是widget的快捷方式；
?????????????intent：表示啟動這個圖標的intent放到數據庫中，當click的時候就會調用這個字段，啟動相應的應用程序；
???????container：表示應用程序的容器，folder的容器為整數，-100：表示在桌面的程序，-101：表示是主屏底部的程序；
???????????screen：表示在第幾個屏，folder的screen都是0, container=-101的為0,1,3,4；2為allapp的按鈕；
?????????????? cellX：表示在屏幕X軸的位置，（0,1,2,3），左上角為0點，往右依次增加；
???????????????cellY：表示在屏幕Y軸的位置，（0,1,2,3），左上角為0點，往下依次增加；
????????????? spallX：表示占X軸幾個格；
????????????? spallY：表示占Y軸幾個格；
???????? itemType：應用程序用0表示，shortcut用1表示，folder用2表示，widget用4表示；
??? appWidgetId：-1表示不是widget，數字大于0表示才是widget；
???????isShortCut：值為0表示不是應用程序的ShortCut，值為1表示是應用程序的ShortCut；
???????? iconType：值為0表示圖標的名字被定義為包名的資源id，值為1表示圖標用bitmap保存；
???????????????? icon：表示應用程序的圖標，二進制的；顯示為一張圖片；
?????? 說明：folder中的應用快捷方式綁定folder---->是用container的值綁定folder的id的；
??????? 詳細的講解請參考LauncherSettings.java這個類，有數據庫字段的詳細講解；
?????????手 機是在第一次燒機完成后，數據庫的值還沒有，這時候launcher解析default_workspace.xml把這個值存到數據庫中；所以說想定制 什么樣的開機桌面就在default_workspace.xml中做相應的配置，具體參照我前面的博客：
Android中源碼Launcher主屏幕程序排列詳解【安卓Launcher進化一】中有詳細的介紹：
?????? i f (!convertDatabase(db))?{
??????????????? ?// Populate favorites table with initial favorites
??????????????? loadFavorites(db, R.xml.default_workspace);
????????}
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??????Step?1：開機后先啟動LauncherApplication.java這個類的onCreate（）方法，下面看代碼：???
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Java代碼??
@Override???public?void?onCreate()?{???????super.onCreate();???????????????????final?int?screenSize?=?getResources().getConfiguration().screenLayout?&???????????????Configuration.SCREENLAYOUT_SIZE_MASK;???????sIsScreenLarge?=?screenSize?==?Configuration.SCREENLAYOUT_SIZE_LARGE?||???????????screenSize?==?Configuration.SCREENLAYOUT_SIZE_XLARGE;???????sScreenDensity?=?getResources().getDisplayMetrics().density;??????????????mIconCache?=?new?IconCache(this);????????????mModel?=?new?LauncherModel(this,?mIconCache);???????????????????IntentFilter?filter?=?new?IntentFilter(Intent.ACTION_PACKAGE_ADDED);???????filter.addAction(Intent.ACTION_PACKAGE_REMOVED);???????filter.addAction(Intent.ACTION_PACKAGE_CHANGED);???????filter.addDataScheme("package");???????registerReceiver(mModel,?filter);???????filter?=?new?IntentFilter();????????????filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE);???????filter.addAction(Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE);???????filter.addAction(Intent.ACTION_LOCALE_CHANGED);???????filter.addAction(Intent.ACTION_CONFIGURATION_CHANGED);???????registerReceiver(mModel,?filter);???????filter?=?new?IntentFilter();???????filter.addAction(SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED);???????registerReceiver(mModel,?filter);???????filter?=?new?IntentFilter();???????filter.addAction(SearchManager.INTENT_ACTION_SEARCHABLES_CHANGED);???????registerReceiver(mModel,?filter);???????????????????ContentResolver?resolver?=?getContentResolver();???????resolver.registerContentObserver(LauncherSettings.Favorites.CONTENT_URI,?true,???????????????mFavoritesObserver);???}?? ? ???????Step 2：在LauncherApplication.java中onTerminate（）的方法，解除監聽的綁定；
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Java代碼??
???@Override?????public?void?onTerminate()?{?????????super.onTerminate();???????????unregisterReceiver(mModel);???????????ContentResolver?resolver?=?getContentResolver();?????????resolver.unregisterContentObserver(mFavoritesObserver);?????}?? ?
???? Step 3：Step1中的數據庫mFavoritesObserver監聽內部類如下：
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Java代碼??
?private?final?ContentObserver?mFavoritesObserver?=?new?ContentObserver(new?Handler())?{???????@Override???????public?void?onChange(boolean?selfChange)?{???????????mModel.startLoader(LauncherApplication.this,?false);???????}???};?? ?
說明：mModel.startLoader（。。，。。）是開啟一個線程，設置線程的優先級NORM_PRIORITY，開始load桌面圖標對應的數據庫，這個過程是和Launcher.onCreate()同時進行的；
????Step 4: 接著我們來看看mModel.startLoader(LauncherApplication.this, false)的方法：
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Java代碼??
public?void?startLoader(Context?context,?boolean?isLaunching)?{???????synchronized?(mLock)?{???????????if?(DEBUG_LOADERS)?{???????????????Log.d(TAG,?"startLoader?isLaunching="?+?isLaunching);???????????}??????????????????????if?(mCallbacks?!=?null?&&?mCallbacks.get()?!=?null)?{?????????????????????????????????????????isLaunching?=?isLaunching?||?stopLoaderLocked();???????????????mLoaderTask?=?new?LoaderTask(context,?isLaunching);???????????????sWorkerThread.setPriority(Thread.NORM_PRIORITY);???????????????sWorker.post(mLoaderTask);???????????}???????}???}?? ??
?? Step 5：接著我們來看看LoaderTask.java的run（）方法：
Java代碼??
public?void?run()?{??????????????????final?Callbacks?cbk?=?mCallbacks.get();??????final?boolean?loadWorkspaceFirst?=?cbk?!=?null???(!cbk.isAllAppsVisible())?:?true;????????keep_running:?{??????????????????????????synchronized?(mLock)?{??????????????if?(DEBUG_LOADERS)?Log.d(TAG,?"Setting?thread?priority?to?"?+??????????????????????(mIsLaunching???"DEFAULT"?:?"BACKGROUND"));??????????????android.os.Process.setThreadPriority(mIsLaunching????????????????????????Process.THREAD_PRIORITY_DEFAULT?:?Process.THREAD_PRIORITY_BACKGROUND);??????????}??????????if?(loadWorkspaceFirst)?{??????????????if?(DEBUG_LOADERS)?Log.d(TAG,?"step?1:?loading?workspace");??????????????loadAndBindWorkspace();??????????}?else?{??????????????if?(DEBUG_LOADERS)?Log.d(TAG,?"step?1:?special:?loading?all?apps");??????????????loadAndBindAllApps();??????????}????????????if?(mStopped)?{??????????????break?keep_running;??????????}????????????????????????????synchronized?(mLock)?{??????????????if?(mIsLaunching)?{??????????????????if?(DEBUG_LOADERS)?Log.d(TAG,?"Setting?thread?priority?to?BACKGROUND");??????????????????android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);??????????????}??????????}??????????waitForIdle();????????????????????if?(loadWorkspaceFirst)?{??????????????if?(DEBUG_LOADERS)?Log.d(TAG,?"step?2:?loading?all?apps");??????????????loadAndBindAllApps();??????????}?else?{??????????????if?(DEBUG_LOADERS)?Log.d(TAG,?"step?2:?special:?loading?workspace");??????????????loadAndBindWorkspace();??????????}????????????????????synchronized?(mLock)?{??????????????android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);??????????}??????}??????????????if?(DEBUG_LOADERS)?Log.d(TAG,?"Comparing?loaded?icons?to?database?icons");??????for?(Object?key?:?sDbIconCache.keySet())?{??????????updateSavedIcon(mContext,?(ShortcutInfo)?key,?sDbIconCache.get(key));??????}??????sDbIconCache.clear();????????????????mContext?=?null;????????synchronized?(mLock)?{??????????????????if?(mLoaderTask?==?this)?{??????????????mLoaderTask?=?null;??????????}??????}??}????public?void?stopLocked()?{??????synchronized?(LoaderTask.this)?{??????????mStopped?=?true;??????????this.notify();??????}??}?? ?
加載桌面圖標對應的數據庫的值，這些值能把這些圖標顯示在屏幕上。
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??? Step 6：LauncherApplication.onCreate()方法啟動完成后，接著開始調用Launcher.java的onCreate()方法。代碼如下：
Java代碼??
@Override??protected?void?onCreate(Bundle?savedInstanceState)?{??????super.onCreate(savedInstanceState);??????????LauncherApplication?app?=?((LauncherApplication)getApplication());??????????????mModel?=?app.setLauncher(this);??????????mIconCache?=?app.getIconCache();??????????mDragController?=?new?DragController(this);??????????mInflater?=?getLayoutInflater();????????????mAppWidgetManager?=?AppWidgetManager.getInstance(this);??????????mAppWidgetHost?=?new?LauncherAppWidgetHost(this,?APPWIDGET_HOST_ID);??????????mAppWidgetHost.startListening();????????if?(PROFILE_STARTUP)?{??????????android.os.Debug.startMethodTracing(??????????????????Environment.getExternalStorageDirectory()?+?"/launcher");??????}????????????checkForLocaleChange();??????????setContentView(R.layout.launcher);??????????setupViews();??????????????????????showFirstRunWorkspaceCling();????????????registerContentObservers();????????lockAllApps();????????mSavedState?=?savedInstanceState;??????restoreState(mSavedState);????????????if?(mAppsCustomizeContent?!=?null)?{??????????mAppsCustomizeContent.onPackagesUpdated();??????}????????if?(PROFILE_STARTUP)?{??????????android.os.Debug.stopMethodTracing();??????}????????if?(!mRestoring)?{??????????mModel.startLoader(this,?true);??????}????????if?(!mModel.isAllAppsLoaded())?{??????????ViewGroup?appsCustomizeContentParent?=?(ViewGroup)?mAppsCustomizeContent.getParent();??????????mInflater.inflate(R.layout.apps_customize_progressbar,?appsCustomizeContentParent);??????}????????????mDefaultKeySsb?=?new?SpannableStringBuilder();??????Selection.setSelection(mDefaultKeySsb,?0);????????????IntentFilter?filter?=?new?IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);??????registerReceiver(mCloseSystemDialogsReceiver,?filter);????????boolean?searchVisible?=?false;??????boolean?voiceVisible?=?false;??????????????int?coi?=?getCurrentOrientationIndexForGlobalIcons();??????if?(sGlobalSearchIcon[coi]?==?null?||?sVoiceSearchIcon[coi]?==?null?||??????????????sAppMarketIcon[coi]?==?null)?{??????????updateAppMarketIcon();??????????searchVisible?=?updateGlobalSearchIcon();??????????voiceVisible?=?updateVoiceSearchIcon(searchVisible);??????}??????if?(sGlobalSearchIcon[coi]?!=?null)?{???????????updateGlobalSearchIcon(sGlobalSearchIcon[coi]);???????????searchVisible?=?true;??????}??????if?(sVoiceSearchIcon[coi]?!=?null)?{??????????updateVoiceSearchIcon(sVoiceSearchIcon[coi]);??????????voiceVisible?=?true;??????}??????if?(sAppMarketIcon[coi]?!=?null)?{??????????updateAppMarketIcon(sAppMarketIcon[coi]);??????}??????mSearchDropTargetBar.onSearchPackagesChanged(searchVisible,?voiceVisible);????????????if?(LauncherApplication.isScreenLarge()?||?Build.TYPE.contentEquals("eng"))?{??????????setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);??????}??}?? ?
??? Step 7：其中LauncherModel這個類中有個回調接口，具體定義如下：
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Java代碼??
public?interface?Callbacks?{?????????public?boolean?setLoadOnResume();?????????public?int?getCurrentWorkspaceScreen();?????????public?void?startBinding();?????????public?void?bindItems(ArrayList<ItemInfo>?shortcuts,?int?start,?int?end);?????????public?void?bindFolders(HashMap<Long,FolderInfo>?folders);?????????public?void?finishBindingItems();?????????public?void?bindAppWidget(LauncherAppWidgetInfo?info);?????????public?void?bindAllApplications(ArrayList<ApplicationInfo>?apps);?????????public?void?bindAppsAdded(ArrayList<ApplicationInfo>?apps);?????????public?void?bindAppsUpdated(ArrayList<ApplicationInfo>?apps);?????????public?void?bindAppsRemoved(ArrayList<ApplicationInfo>?apps,?boolean?permanent);?????????public?void?bindPackagesUpdated();?????????public?boolean?isAllAppsVisible();?????????public?void?bindSearchablesChanged();?????}?? ?
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對LauncherModel進行初始化的時候mModel = app.setLauncher(this);---->mModel.initialize(launcher);----->
???????????? ?public void initialize(Callbacks callbacks) {
????????????????????? synchronized (mLock) {
????????????????????????????? mCallbacks = new WeakReference<Callbacks>(callbacks);
????????????????????? ?}
?????????????? }
這 個callbacks就是定義的接口回調，具體實現是在Launcher.java中定義的，啟動Launcher的過程中，這些實現是異步來實現的。還 有Launcher.java的onResume（）方法沒有講解，到這兒基本上Android的Launcher已經啟動起來了，這個 onResume（）我研究后再更新。
????? 歡迎各界同僚留言指正錯誤和拍磚！歡迎留言！
轉載于:https://www.cnblogs.com/xiaochao1234/p/4054109.html
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