第一步：我们先从LauncherApplication.java开始，先找到onCreate（）方法：
源码打印？
public void onCreate() {
//设置最小堆内存8M
VMRuntime.getRuntime().setMinimumHeapSize(8 * 1024 * 1024); //llx modify the heapsize
super.onCreate();
//建立应用图标缓存器
mIconCache = new IconCache(this);
//建立LauncherModel
mModel = new LauncherModel(this, mIconCache);
// Register intent receivers
//注册Intent.ACTION_PACKAGE_ADDED，Intent.ACTION_PACKAGE_REMOVED，
//Intent.ACTION_EXTERNAL_APPLICATIONS_AVAILABLE，
//Intent.ACTION_LOCALE_CHANGED 事件监听器
//LauncherModel作为广播接收器对上面事件进行监听
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);
registerReceiver(mModel, filter);
filter = new IntentFilter();
filter.addAction(Intent.ACTION_LOCALE_CHANGED);
registerReceiver(mModel, filter);
// Register for changes to the favorites
//添加对桌面favorites content provider 数据变化监听器
ContentResolver resolver = getContentResolver();
resolver.registerContentObserver(LauncherSettings.Favorites.CONTENT_URI, true,mFavoritesObserver);
}
第二步：看下Launcher.java中的onCreate（）方法：
源码打印？
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//获取LauncherApplication LauncherModel mIconCache等LauncherApplication初始化的对象
LauncherApplication app = ((LauncherApplication)getApplication());
mModel = app.setLauncher(this);
mIconCache = app.getIconCache();
//新建拖放控制器new DragController（this）
mDragController = new DragController(this);
mInflater = getLayoutInflater();
//获取桌面组件管理器，启动桌面组件host
mAppWidgetManager = AppWidgetManager.getInstance(this);
mAppWidgetHost = new LauncherAppWidgetHost(this, APPWIDGET_HOST_ID);
mAppWidgetHost.startListening();
if (PROFILE_STARTUP) {
android.os.Debug.startMethodTracing("/sdcard/launcher");
}
//从array.hotseats中加载所有的hotseats
loadHotseats();
//从加载本地设置
checkForLocaleChange();setWallpaperDimension();
//加载布局文件
setContentView(R.layout.launcher);
//初始化所有控件
setupViews();
registerContentObservers();
lockAllApps();
//从Bundle savedInstanceState获取桌面持久化数据
mSavedState = savedInstanceState;
restoreState(mSavedState);
if (PROFILE_STARTUP) {
android.os.Debug.stopMethodTracing();
}
if (!mRestoring) {
//LauncherModel.Loader.startLoader（） 代码同步处理
mModel.startLoader(this, true);
}
// For handling default keys
mDefaultKeySsb = new SpannableStringBuilder();
Selection.setSelection(mDefaultKeySsb, 0);
//注册Intent.ACTION_CLOSE_SYSTEM_DIALOGS广播监听
IntentFilter filter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);
registerReceiver(mCloseSystemDialogsReceiver, filter);
}
第三步：加载桌面项: 在LauncherModel.java的Thread的run方法, 是在主线程完成以后才开始加载。
源码打印？
public void run() {
// Optimize for end-user experience: if the Launcher is up and // running with the
// All Apps interface in the foreground, load All Apps first. Otherwise, load the
// workspace first (default).
final Callbacks cbk = mCallbacks.get();
final boolean loadWorkspaceFirst = cbk != null ? (!cbk.isAllAppsVisible()) : true;
keep_running: {
// Elevate priority when Home launches for the first time to avoid
// starving at boot time. Staring at a blank home is not cool.
synchronized (mLock) {
android.os.Process.setThreadPriority(mIsLaunching
? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND);
}
//判断是否先加载桌面
if (loadWorkspaceFirst) {
if (DEBUG_LOADERS) Log.d(TAG, "step 1: loading workspace");
//从数据库launcher.db中查询中所有桌面项构造对应类型的ItemInfo对象存入
loadAndBindWorkspace();
} else {
if (DEBUG_LOADERS) Log.d(TAG, "step 1: special: loading all apps");
loadAndBindAllApps();
}
if (mStopped) {
break keep_running;
}
// Whew! Hard work done.Slow us down, and wait until the UI thread has
// settled down.
synchronized (mLock) {
if (mIsLaunching) {
android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
}
}
waitForIdle();
// second step
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();
}
}
这里调用了Launcher.java中startBinding方法
public void startBinding() {
final Workspace workspace = mWorkspace;
int count = workspace.getChildCount();
for (int i = 0; i < count; i++) {
// Use removeAllViewsInLayout() to avoid an extra requestLayout() and invalidate().
((ViewGroup) workspace.getChildAt(i)).removeAllViewsInLayout();
}
if (DEBUG_USER_INTERFACE) {
android.widget.Button finishButton = new android.widget.Button(this);
finishButton.setText("Finish");
workspace.addInScreen(finishButton, 1, 0, 0, 1, 1);
finishButton.setOnClickListener(new android.widget.Button.OnClickListener() {
public void onClick(View v) {
finish();
}
});
}
}
还有Launcher.java的bindItem()方法：
public void bindItems(ArrayList<ItemInfo> shortcuts, int start, int end) {
setLoadOnResume();
//获取桌面的celllayout对象，也就是workspace下5个用户桌面中的一个
final Workspace workspace = mWorkspace;
for (int i=start; i<end; i++) {
//根据ItemInfo对象创建桌面图标view对象
final ItemInfo item = shortcuts.get(i);
mDesktopItems.add(item);
switch (item.itemType) {
case LauncherSettings.Favorites.ITEM_TYPE_APPLICATION:
case LauncherSettings.Favorites.ITEM_TYPE_SHORTCUT:
final View shortcut = createShortcut((ShortcutInfo)item);
//获取item.screen， item.cellX， item.cellY， spanX， spanY并添加到屏幕上。
workspace.addInScreen(shortcut, item.screen, item.cellX, item.cellY, 1, 1,false);
break;
case LauncherSettings.Favorites.ITEM_TYPE_USER_FOLDER:
final FolderIcon newFolder = FolderIcon.fromXml(R.layout.folder_icon, this,
(ViewGroup) workspace.getChildAt(workspace.getCurrentScreen()),
(UserFolderInfo) item);
workspace.addInScreen(newFolder, item.screen, item.cellX, item.cellY, 1, 1,false);
break;
case LauncherSettings.Favorites.ITEM_TYPE_LIVE_FOLDER:
final FolderIcon newLiveFolder = LiveFolderIcon.fromXml(
R.layout.live_folder_icon, this,
(ViewGroup) workspace.getChildAt(workspace.getCurrentScreen()),
(LiveFolderInfo) item);
workspace.addInScreen(newLiveFolder, item.screen, item.cellX, item.cellY, 1, 1,false);
break;
}
}
//.重新设置桌面图标view 的layoutparam（类型为cellLayout.layoutparam）
workspace.requestLayout();
}
注意，这两个方法都是异步调用。原因应该很清楚：时间。
另外还要注意一下两点：
1.桌面图标view对象添加OnLongClickListener=laucher，由laucher负责监听桌面图标view的longclick事件
2.如果桌面图标是DropTarget对象，拖放控制器mDragController添加该view到拖放目的地列表
在Launcher.java的代码中有bindFolders()和bindAppWidget()方法，都是回调方法。主要看下bindAppWidget()方法吧。
/**
* Add the views for a widget to the workspace.
*
* Implementation of the method from LauncherModel.Callbacks.
*/
public void bindAppWidget(LauncherAppWidgetInfo item) {
setLoadOnResume();
final long start = DEBUG_WIDGETS ? SystemClock.uptimeMillis() : 0;
if (DEBUG_WIDGETS) {
Log.d(TAG, "bindAppWidget: " + item);
}
final Workspace workspace = mWorkspace;
//获取LauncherAppWidgetInfo的appWidgetId
final int appWidgetId = item.appWidgetId;
//根据appWidgetInfo创建桌面组件的view AppWidgetHostView对象
final AppWidgetProviderInfo appWidgetInfo = mAppWidgetManager.getAppWidgetInfo(appWidgetId);
if (DEBUG_WIDGETS) {
Log.d(TAG, "bindAppWidget: id=" + item.appWidgetId + " belongs to component " + appWidgetInfo.provider);
}
item.hostView = mAppWidgetHost.createView(this, appWidgetId, appWidgetInfo);
item.hostView.setAppWidget(appWidgetId, appWidgetInfo);
item.hostView.setTag(item);
//添加到对应桌面的cell
workspace.addInScreen(item.hostView, item.screen, item.cellX,
item.cellY, item.spanX, item.spanY, false);
workspace.requestLayout();
mDesktopItems.add(item);
if (DEBUG_WIDGETS) {
Log.d(TAG, "bound widget id="+item.appWidgetId+" in "
+ (SystemClock.uptimeMillis()-start) + "ms");
}
}
<span style="font-size:16px;">
</span>
当都加载完成以后会执行finishBindingItems（）：
/**
* Callback saying that there aren't any more items to bind.
*
* Implementation of the method from LauncherModel.Callbacks.
*/
public void finishBindingItems() {
setLoadOnResume();
if (mSavedState != null) {
if (!mWorkspace.hasFocus()) {
mWorkspace.getChildAt(mWorkspace.getCurrentScreen()).requestFocus();
}
final long[] userFolders = mSavedState.getLongArray(RUNTIME_STATE_USER_FOLDERS);
if (userFolders != null) {
for (long folderId : userFolders) {
final FolderInfo info = sFolders.get(folderId);
if (info != null) {
openFolder(info);
}
}
final Folder openFolder = mWorkspace.getOpenFolder();
if (openFolder != null) {
openFolder.requestFocus();
}
}
mSavedState = null;
}
if (mSavedInstanceState != null) {
super.onRestoreInstanceState(mSavedInstanceState);
mSavedInstanceState = null;
}
mWorkspaceLoading = false;
}
前面那三个都是都是回调方法，控制器当然是LauncherModel.java了，让我们在代码里看一下：
其接口定义如下：
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 boolean isAllAppsVisible();
}
想看仔细的，自己可以在代码中找一下。
最后执行 bindAllApplications() , bindAppsAdded()方法：
public void bindAllApplications(ArrayList<ApplicationInfo> apps) {
mAllAppsGrid.setApps(apps);
}
/**
* A package was installed.
*
* Implementation of the method from LauncherModel.Callbacks.
*/
public void bindAppsAdded(ArrayList<ApplicationInfo> apps) {
setLoadOnResume();
removeDialog(DIALOG_CREATE_SHORTCUT);
mAllAppsGrid.addApps(apps);
}
到这基本上就是整个的启动过程了。
