Launcher3 loadAndBindWorkspace

看一下LauncherModel是怎么加载应用的

在LoaderTask的run方法中调用了

/** Returns whether this is an upgrade path */

private boolean loadAndBindWorkspace() {
    mIsLoadingAndBindingWorkspace = true;
    boolean isUpgradePath = false;
    if (!mWorkspaceLoaded) {
        isUpgradePath = loadWorkspace();
        synchronized (LoaderTask.this) {
            if (mStopped) {
                return isUpgradePath;
            }
            mWorkspaceLoaded = true;
        }
    }
    // Bind the workspace
    bindWorkspace(-1, isUpgradePath);
    return isUpgradePath;
}

关键代码：

 isUpgradePath = loadWorkspace();//加载应用

 bindWorkspace(-1, isUpgradePath);//将应用添加到主屏上

private boolean loadWorkspace() {

   final Context context = mContext;
  final ContentResolver contentResolver = context.getContentResolver();
  final PackageManager manager = context.getPackageManager();
  final AppWidgetManager widgets = AppWidgetManager.getInstance(context);

  //初始化变量

  final boolean  isSdCardReady = context.registerReceiver( null ,

new IntentFilter(StartupReceiver.SYSTEM_READY)) != null

   //这个真没搞懂是干啥的应该和sd卡上的应用有关系吧

   DeviceProfile grid = app.getDynamicGrid().getDeviceProfile();

  int countX = (int) grid.numColumns;
  int countY = (int) grid.numRows;

//DeviceProfile 存储了布局信息，拿到网格x,y的值

  if ((mFlags & LOADER_FLAG_CLEAR_WORKSPACE) != 0) {

Launcher.addDumpLog(TAG, "loadWorkspace: resetting launcher database", true);
    LauncherAppState.getLauncherProvider().deleteDatabase();
  }

//判断是否需要删除数据库

  if ((mFlags & LOADER_FLAG_MIGRATE_SHORTCUTS) != 0) {
    // append the user's Launcher2 shortcuts
     Launcher.addDumpLog(TAG, "loadWorkspace: migrating from launcher2", true);
     LauncherAppState.getLauncherProvider().migrateLauncher2Shortcuts();
  } else {
    // Make sure the default workspace is loaded
     Launcher.addDumpLog(TAG, "loadWorkspace: loading default favorites", false);
     LauncherAppState.getLauncherProvider().loadDefaultFavoritesIfNecessary();
  }

//从launcher2的数据库加载布局，或者加载默认布局

先看migrateLauncher2Shortcuts

  这个方法体里面主要的操作是

  c = resolver.query(uri, null, null, null, "title ASC")

  查询launcher2的contentprovider

  遍历cursor

  if (itemType != Favorites.ITEM_TYPE_FOLDER)

  如果item并不是文件夹，获取intent

  intent = Intent.parseUri(intentStr, 0）

  cn = intent.getComponent();

  LauncherModel.isValidPackageActivity(mContext, cn,userHandle)

  //判断获取的应用是否有效

//判断的方式：android L>>LauncherApps isActivityEnabled  (LauncherApps 通过getSystemService("launcherApp")得到)    

     低版本 >> ActivityInfo info = mPm.getActivityInfo(component, 0);

                        return info != null && info.isEnabled()

构造contentvalue，设置value的值，将所有数据遍历完之后放入一个集合中，开启事务，遍历集合，将所有数据存入数据库，然后，保存screen数据到数据库中。 遍历的时候根据item的类型有不同的操作，可以进去看一下，这里不详细分析了

看loadDefaultFavoritesIfNecessary（）

 WorkspaceLoader loader 这个东西没看懂，字面上是workspace加载器

 WorkspaceLoader loader = AutoInstallsLayout.get(getContext(),

mOpenHelper.mAppWidgetHost, mOpenHelper);

这个方法不知道做了什么操作，跟进去也没看明白，反正就是queryBroadcastReceivers（）

   获取指定intent（"android.autoinstalls.config.action.PLAY_AUTO_INSTALL"）的应用，说实话，真心没懂这个intent是干嘛的，Android L增加了很多新api

 Partner partner 这个也没看懂

 loader = new SimpleWorkspaceLoader(mOpenHelper, getContext().getResources(),

getDefaultWorkspaceResourceId());

创建加载器 getDefaultWorkspaceResourceId 这个获取带不带抽屉的default_workspace.xml

mOpenHelper.loadFavorites(mOpenHelper.getWritableDatabase(), loader);//关键代码，加载保存数据

进入private int loadFavorites(SQLiteDatabase db, WorkspaceLoader loader){. ..}

获取每个节点定义的内容，构造ContentVaule

if (TAG_FAVORITE.equals(name)) {
    long id = addAppShortcut(db, values, parser);
    added = id >= 0;
} else if (TAG_APPWIDGET.equals(name)) {
    added = addAppWidget(parser, type, db, values);
} else if (TAG_SHORTCUT.equals(name)) {
    long id = addUriShortcut(db, values, res, parser);
    added = id >= 0;
} else if (TAG_RESOLVE.equals(name)) {
    // This looks through the contained favorites (or meta-favorites) and
    // attempts to add them as shortcuts in the fallback group's location
    // until one is added successfully.
    added = false;
    final int groupDepth = parser.getDepth();
    while ((type = parser.next()) != XmlPullParser.END_TAG ||
            parser.getDepth() > groupDepth) {
        if (type != XmlPullParser.START_TAG) {
            continue;
        }
        final String fallback_item_name = parser.getName();
        if (!added) {
            if (TAG_FAVORITE.equals(fallback_item_name)) {
                final long id = addAppShortcut(db, values, parser);
                added = id >= 0;
            } else {
                Log.e(TAG, "Fallback groups can contain only favorites, found "
                        + fallback_item_name);
            }
        }
    }
 } else if (TAG_FOLDER.equals(name)) {
    // Folder contents are nested in this XML file
    added = loadFolder(db, values, res, parser);

}else if (TAG_PARTNER_FOLDER.equals(name)) {

// Folder contents come from an external XML resource
    final Partner partner = Partner.get(mPackageManager);
    if (partner != null) {
        final Resources partnerRes = partner.getResources();
        final int resId = partnerRes.getIdentifier(Partner.RES_FOLDER,
                "xml", partner.getPackageName());
        if (resId != 0) {
            final XmlResourceParser partnerParser = partnerRes.getXml(resId);
            beginDocument(partnerParser, TAG_FOLDER);
            added = loadFolder(db, values, partnerRes, partnerParser);
        }
    }
}

根据定义的内容不同做不同的操作（item类型不同）

都是把不同的item，构造ContentValue,设置不同的值，然后存入数据库中

其中loadFolder，把XmlpullPaser传过去，又做了一次递归读取文档的操作，遍历，然后将子item存入数据库，然后会判断 folder里面包含的数据，如果小于2，则会删除文件夹，将数据重新存入数据库，改变container为桌面

还有一个Resolve的标签，会将这个标签下的应用第一个加载到数据库，

然后将返回screen count

对screen排序，然后插入数据库

然后计算

mMaxItemId = initializeMaxItemId(db);
mMaxScreenId = initializeMaxScreenId(db);

默认布局加载完毕

int count = loader.loadLayout(db, screenIds);

最后调用了loadFavoritesRecursive//递归加载default_workspace.xml定义的内容

进入loadFavoritesRecursive

这里面做的操作就是使用XmlResourceParser解析xml文件