Launcher3分析<一>

安卓開發 · 發表 2018-09-19 18:28:18

摘要：前言最近需要實現一個自己的Launcher，就藉機學習下原生的Launcher原始碼。多個Launcher 原始碼裡有Launcher，Launcher2，Launcher3。那它們有什麼區別呢。 launcher不支援桌面小工具動畫效果，launcher2添加了動畫效果和...

前言

最近需要實現一個自己的Launcher，就藉機學習下原生的Launcher原始碼。

多個Launcher

原始碼裡有Launcher，Launcher2，Launcher3。那它們有什麼區別呢。

launcher不支援桌面小工具動畫效果，launcher2添加了動畫效果和3D初步效果支援。

Android 4.4 (KK)開始Launcher預設使用Launcher3，Launcher3較Launcher2 UI 有部分調整，主要包括:

狀態列透明，App List 透Wallpaper；
增加overview模式，可以調整workspace上頁面的前後順序；
動態管理螢幕數量；
widget列表與app list分開顯示；

預設不支援預置appwidget，需要使用者指定許可權；

提供類似小米只有workspace的桌面機制 ；

Wallpaper 的程式碼全部搬移到Launcher包；

```
類似Cling等細節的小變化；
```

那我們就直接研究最新的Launcher3

Launcher3

Launcher3介紹

Launcher是開機啟動的第一個應用程式，用來展示應用列表和快捷方式、小部件等。

Launcher3原始碼解析

AndroidManifest.xml

一些標籤屬性

123.png

LauncherApplication

public class LauncherApplication extends Application {
@Override
public void onCreate() {
super.onCreate();
LauncherAppState.setApplicationContext(this);
LauncherAppState.getInstance();
}

@Override
public void onTerminate() {
super.onTerminate();
LauncherAppState.getInstance().onTerminate();
}
}

初始化LauncherAppState類，在繼續看LauncherAppState類。

private LauncherAppState() {
...


// set sIsScreenXLarge and mScreenDensity *before* creating icon cache
mIsScreenLarge = isScreenLarge(sContext.getResources());
mScreenDensity = sContext.getResources().getDisplayMetrics().density;

mWidgetPreviewCacheDb = new WidgetPreviewLoader.CacheDb(sContext);
mIconCache = new IconCache(sContext);

mAppFilter = AppFilter.loadByName(sContext.getString(R.string.app_filter_class));
mModel = new LauncherModel(this, mIconCache, mAppFilter);

// Register intent receivers
IntentFilter filter = new IntentFilter(Intent.ACTION_PACKAGE_ADDED);
filter.addAction(Intent.ACTION_PACKAGE_REMOVED);
filter.addAction(Intent.ACTION_PACKAGE_CHANGED);
filter.addDataScheme("package");
sContext.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);
sContext.registerReceiver(mModel, filter);
filter = new IntentFilter();
filter.addAction(SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED);
sContext.registerReceiver(mModel, filter);
filter = new IntentFilter();
filter.addAction(SearchManager.INTENT_ACTION_SEARCHABLES_CHANGED);
sContext.registerReceiver(mModel, filter);

// Register for changes to the favorites
ContentResolver resolver = sContext.getContentResolver();
resolver.registerContentObserver(LauncherSettings.Favorites.CONTENT_URI, true,
mFavoritesObserver);
}

初始化中讀取配置，註冊廣播，例項化LauncherModel。Launcher2原始碼 LauncherModel建立是在LauncherApplication ,Launcher3移到這個類來了。

/**
 * Maintains in-memory state of the Launcher. It is expected that there should be only one
 * LauncherModel object held in a static. Also provide APIs for updating the database state
 * for the Launcher.
 */

單例，處理資料庫。這個類繼承BroadcastReceiver ，我們來重點看下這個類實現；

LauncherModel

private static final HandlerThread sWorkerThread = new HandlerThread("launcher-loader");
static {
sWorkerThread.start();
}
private static final Handler sWorker = new Handler(sWorkerThread.getLooper());

建立一個執行緒，用來處理

LoaderTask 載入

workspace icons
widgets
all apps icons
PackageUpdatedTask 用來更新applist.
看一下構造方法

LauncherModel(LauncherAppState app, IconCache iconCache, AppFilter appFilter) {
final Context context = app.getContext();

mAppsCanBeOnRemoveableStorage = Environment.isExternalStorageRemovable();
mApp = app;
mBgAllAppsList = new AllAppsList(iconCache, appFilter);
mIconCache = iconCache;

mDefaultIcon = Utilities.createIconBitmap(
mIconCache.getFullResDefaultActivityIcon(), context);

final Resources res = context.getResources();
Configuration config = res.getConfiguration();
mPreviousConfigMcc = config.mcc; // SIM卡相關
}

傳入LauncherAppState 來獲取 context，WidgetPreviewLoader.CacheDb操作資料庫；

IconCache類是用來快取app圖示

LauncherModle繼承BroadcastReceiver 我們看下onReceive做了什麼處理；

/**
* Call from the handler for ACTION_PACKAGE_ADDED, ACTION_PACKAGE_REMOVED and
* ACTION_PACKAGE_CHANGED.
*/
@Override
public void onReceive(Context context, Intent intent) {
...
if (Intent.ACTION_PACKAGE_CHANGED.equals(action)
|| Intent.ACTION_PACKAGE_REMOVED.equals(action)
|| Intent.ACTION_PACKAGE_ADDED.equals(action)) {
final String packageName = intent.getData().getSchemeSpecificPart();
final boolean replacing = intent.getBooleanExtra(Intent.EXTRA_REPLACING, false);

int op = PackageUpdatedTask.OP_NONE;

if (packageName == null || packageName.length() == 0) {
// they sent us a bad intent
return;
}

if (Intent.ACTION_PACKAGE_CHANGED.equals(action)) {
op = PackageUpdatedTask.OP_UPDATE;
} else if (Intent.ACTION_PACKAGE_REMOVED.equals(action)) {
if (!replacing) {
op = PackageUpdatedTask.OP_REMOVE;
}
// else, we are replacing the package, so a PACKAGE_ADDED will be sent
// later, we will update the package at this time
} else if (Intent.ACTION_PACKAGE_ADDED.equals(action)) {
if (!replacing) {
op = PackageUpdatedTask.OP_ADD;
} else {
op = PackageUpdatedTask.OP_UPDATE;
}
}

if (op != PackageUpdatedTask.OP_NONE) {
enqueuePackageUpdated(new PackageUpdatedTask(op, new String[] { packageName }));
}
//移動APP完成之後，發出的廣播
} else if (Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE.equals(action)) {
// First, schedule to add these apps back in.
String[] packages = intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
enqueuePackageUpdated(new PackageUpdatedTask(PackageUpdatedTask.OP_ADD, packages));
// Then, rebind everything.
startLoaderFromBackground();
//正在移動APP時，發出的廣播
} else if (Intent.ACTION_EXTERNAL_APPLICATIONS_UNAVAILABLE.equals(action)) {
String[] packages = intent.getStringArrayExtra(Intent.EXTRA_CHANGED_PACKAGE_LIST);
enqueuePackageUpdated(new PackageUpdatedTask(
PackageUpdatedTask.OP_UNAVAILABLE, packages));
} else if (Intent.ACTION_LOCALE_CHANGED.equals(action)) { //裝置當前區域設定已更改時發出的廣播
// If we have changed locale we need to clear out the labels in all apps/workspace.
forceReload();
//裝置當前設定被改變時發出的廣播(包括的改變:介面語言，裝置方向，等
} else if (Intent.ACTION_CONFIGURATION_CHANGED.equals(action)) {
// Check if configuration change was an mcc/mnc change which would affect app resources
// and we would need to clear out the labels in all apps/workspace. Same handling as
// above for ACTION_LOCALE_CHANGED
Configuration currentConfig = context.getResources().getConfiguration();
if (mPreviousConfigMcc != currentConfig.mcc) {
Log.d(TAG, "Reload apps on config change. curr_mcc:"
+ currentConfig.mcc + " prevmcc:" + mPreviousConfigMcc);
forceReload();
}
// Update previousConfig
mPreviousConfigMcc = currentConfig.mcc;
} else if (SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED.equals(action) ||
SearchManager.INTENT_ACTION_SEARCHABLES_CHANGED.equals(action)) {
if (mCallbacks != null) {
Callbacks callbacks = mCallbacks.get();
if (callbacks != null) {
callbacks.bindSearchablesChanged();
}
}
}
}

接收應用安裝解除安裝後的廣播，當接收到廣播呼叫enqueuePackageUpdated來啟動這個任務。

public void run() {
final Context context = mApp.getContext();

final String[] packages = mPackages;
final int N = packages.length;
switch (mOp) {
case OP_ADD:
for (int i=0; i<N; i++) {
if (DEBUG_LOADERS) Log.d(TAG, "mAllAppsList.addPackage " + packages[i]);
mBgAllAppsList.addPackage(context, packages[i]);
}
break;
case OP_UPDATE:
for (int i=0; i<N; i++) {
if (DEBUG_LOADERS) Log.d(TAG, "mAllAppsList.updatePackage " + packages[i]);
mBgAllAppsList.updatePackage(context, packages[i]);
WidgetPreviewLoader.removePackageFromDb(
mApp.getWidgetPreviewCacheDb(), packages[i]);
}
break;
case OP_REMOVE:
case OP_UNAVAILABLE:
for (int i=0; i<N; i++) {
if (DEBUG_LOADERS) Log.d(TAG, "mAllAppsList.removePackage " + packages[i]);
mBgAllAppsList.removePackage(packages[i]);
WidgetPreviewLoader.removePackageFromDb(
mApp.getWidgetPreviewCacheDb(), packages[i]);
}
break;
}
....

if (added != null) {
// Ensure that we add all the workspace applications to the db
Callbacks cb = mCallbacks != null ? mCallbacks.get() : null;
if (!AppsCustomizePagedView.DISABLE_ALL_APPS) {
addAndBindAddedApps(context, new ArrayList<ItemInfo>(), cb, added);
} else {
final ArrayList<ItemInfo> addedInfos = new ArrayList<ItemInfo>(added);
addAndBindAddedApps(context, addedInfos, cb, added);
}
}
}

安裝應用向AllAppsList新增應用資訊；

解除安裝應用向AllAppsList 刪除資料，並刪除資料庫的資料。

呼叫addAndBindAddedApps方法 :處理新新增的應用程式並首先將它們新增到資料庫中;

callbacks.bindAppsAdded(addedWorkspaceScreensFinal,
addNotAnimated, addAnimated, allAppsApps);

回撥到Launcher 主Activity中，這個callback是Launcher初始化後呼叫的，我們後面在介紹。

定義

public interface Callbacks {
//如果Launcher在載入完成之前被強制暫停，那麼需要通過這個回撥方法通知Launcher
//在它再次顯示的時候重新執行載入過程
public boolean setLoadOnResume();
//獲取當前螢幕序號
public int getCurrentWorkspaceScreen();
//啟動桌面資料繫結
public void startBinding();
//批量繫結桌面元件：快捷方式列表，列表的開始位置，列表結束的位置，是否使用動畫
public void bindItems(ArrayList<ItemInfo> shortcuts, int start, int end,
boolean forceAnimateIcons);
//批量繫結桌面頁，orderedScreenIds 序列化後的桌面頁列表
public void bindScreens(ArrayList<Long> orderedScreenIds);
public void bindAddScreens(ArrayList<Long> orderedScreenIds);
//批量繫結資料夾，folders 資料夾對映列表
public void bindFolders(LongArrayMap<FolderInfo> folders);
//繫結任務完成
public void finishBindingItems();
//批量繫結小部件，info 需要繫結到桌面上的小部件資訊
public void bindAppWidget(LauncherAppWidgetInfo info);
//繫結應用程式列表介面的應用程式資訊，apps 需要繫結到應用程式列表中的應用程式列表
public void bindAllApplications(ArrayList<AppInfo> apps);
// Add folders in all app list.
public void bindAllApplications2Folder(ArrayList<AppInfo> apps, ArrayList<ItemInfo> items);
//批量新增元件
public void bindAppsAdded(ArrayList<Long> newScreens,
ArrayList<ItemInfo> addNotAnimated,
ArrayList<ItemInfo> addAnimated,
ArrayList<AppInfo> addedApps);
//批量更新應用程式相關的快捷方式或者入口
public void bindAppsUpdated(ArrayList<AppInfo> apps);
public void bindShortcutsChanged(ArrayList<ShortcutInfo> updated,
ArrayList<ShortcutInfo> removed, UserHandleCompat user);
public void bindWidgetsRestored(ArrayList<LauncherAppWidgetInfo> widgets);
public void bindRestoreItemsChange(HashSet<ItemInfo> updates);
// 從桌面移除一些元件，當應用程式被移除或者禁用的時候呼叫
public void bindComponentsRemoved(ArrayList<String> packageNames,
ArrayList<AppInfo> appInfos, UserHandleCompat user, int reason);
public void bindAllPackages(WidgetsModel model);
//全域性搜尋或者搜尋屬性更新
public void bindSearchablesChanged();
public boolean isAllAppsButtonRank(int rank);
/**
* 指示正在繫結的頁面
* @param page桌面頁序號
*/
public void onPageBoundSynchronously(int page);
//輸出當前Launcher資訊到本地檔案中
public void dumpLogsToLocalData();
}

介面都是在Launcher這個類實現的。

總結

LauncherModel 是一個廣播接收者BroadcastReceiver，監聽應用的安裝、解除安裝、移動等事件。
啟動LoaderTask 初始化Launcher資料
Over