Android Launcher源码研究(二) 加载app流程1

今天主要分析Android Launcher源码中的一些重要类之间的关系，基本的加载流程。先来看一个类图

  Launcher.java 是主Activity 在onCreate方法里面初始化了LauncherMode实例.

LauncherApplication app = ((LauncherApplication)getApplication());

mModel = app.setLauncher(this);

直接进入LauncherApplication.java的方法 

    LauncherModel setLauncher(Launcher launcher) {
        mModel.initialize(launcher);
        return mModel;
    }

这里的mModel就是LauncherModel类了，LauncherModel扮演者重要的角色，实际上是个广播,监控app的安装，改变，和卸载另外就是加载所有app信息

这里Launcher实现了Callbacks接口，直接加入到callbacks列表中，后面的很多功能都要靠它回调处理

    public void initialize(Callbacks callbacks) {
        synchronized (mLock) {
            mCallbacks = new WeakReference<Callbacks>(callbacks);
        }
    }

在Launcher.java  onCreate的代码中看下面的一段代码.

        if (!mRestoring) {
            if (sPausedFromUserAction) {
                // If the user leaves launcher, then we should just load items asynchronously when
                // they return.
                mModel.startLoader(true, -1);
            } else {
                // We only load the page synchronously if the user rotates (or triggers a
                // configuration change) while launcher is in the foreground
                mModel.startLoader(true, mWorkspace.getCurrentPage());
            }
        }

源码中注释也显示了2中情况，一种是当前用户的界面不是桌面可能是某个应用程序界面 这样我们通过后台异步加载。

另外一种情况是 刷新当前页面的app信息数据. 

现在定位到LauncherMode.java源码中startLoader方法 部分代码如下.

                if (synchronousBindPage > -1 && mAllAppsLoaded && mWorkspaceLoaded) {
                    mLoaderTask.runBindSynchronousPage(synchronousBindPage);//同步加载当前页
                } else {
                    sWorkerThread.setPriority(Thread.NORM_PRIORITY);
                    sWorker.post(mLoaderTask);//异步加载
                }

和上面讲的一样，加载当前页面信息还是更新所有信息. synchronousBindPage就是当前用户滑动到第几个屏幕，一共是5个屏幕.

我们用到了LoaderTask这个类是一个Runnable实现.  这个地方用的是HandlerThread (这个类我以前没用过，一直是自己获取Looper再处理的 )

这个类就是具体载入appinfo，appwidget，  folder的信息了。

我们看看LoaderTask run方法实现. 注意 LoaderTask 是LauncherMode的内部类.  

            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) {
                    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();//第一次载入
                } else {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: special: loading all apps");
                    loadAndBindAllApps(); //更新数据
                }

                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) {
                        if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to BACKGROUND");
                        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();
                }

                // Restore the default thread priority after we are done loading items
                synchronized (mLock) {
                    android.os.Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
                }
            }

按照源码的注释 是第一次加载workspace , 第二次加载所有的app 信息，你会发现 loadAndBindAllApps方法和loadAndBindWorkspace 2次调用是倒着的。

我的理解就是  先执行加载workspace 再执行加载all apps.

我们定位到 loadAndBindWorkspace方法中，

   if (!mWorkspaceLoaded) {
                loadWorkspace();
                synchronized (LoaderTask.this) {
                    if (mStopped) {
                        return;
                    }
                    mWorkspaceLoaded = true;
                }
            }

如果workspace还没加载就调用loadWorkspace方法. 定位到这个方法里面，一目了然发现 都是直接获取应用程序信息了包括widget.

直接调用了 PackageManager，AppWidgetManager，ContentResolver 获取信息.

读取信息保存后 我们需要与workspace汇合，这个地方是调用bindWorkspace

在这个方面里面我们会发现使用前面说的callbacks进行回调完整数据与View的绑定显示.

      /**
         * Binds all loaded data to actual views on the main thread.
         */
        private void bindWorkspace(int synchronizeBindPage) {
            final long t = SystemClock.uptimeMillis();
            Runnable r;

            // Don't use these two variables in any of the callback runnables.
            // Otherwise we hold a reference to them.
            final Callbacks oldCallbacks = mCallbacks.get();
            if (oldCallbacks == null) {
                // This launcher has exited and nobody bothered to tell us.  Just bail.
                Log.w(TAG, "LoaderTask running with no launcher");
                return;
            }

            final boolean isLoadingSynchronously = (synchronizeBindPage > -1);
            final int currentScreen = isLoadingSynchronously ? synchronizeBindPage :
                oldCallbacks.getCurrentWorkspaceScreen();

            // Load all the items that are on the current page first (and in the process, unbind
            // all the existing workspace items before we call startBinding() below.
            unbindWorkspaceItemsOnMainThread();
            ArrayList<ItemInfo> workspaceItems = new ArrayList<ItemInfo>();
            ArrayList<LauncherAppWidgetInfo> appWidgets =
                    new ArrayList<LauncherAppWidgetInfo>();
            HashMap<Long, FolderInfo> folders = new HashMap<Long, FolderInfo>();
            HashMap<Long, ItemInfo> itemsIdMap = new HashMap<Long, ItemInfo>();
            synchronized (sBgLock) {
                workspaceItems.addAll(sBgWorkspaceItems);
                appWidgets.addAll(sBgAppWidgets);
                folders.putAll(sBgFolders);
                itemsIdMap.putAll(sBgItemsIdMap);
            }

            ArrayList<ItemInfo> currentWorkspaceItems = new ArrayList<ItemInfo>();
            ArrayList<ItemInfo> otherWorkspaceItems = new ArrayList<ItemInfo>();
            ArrayList<LauncherAppWidgetInfo> currentAppWidgets =
                    new ArrayList<LauncherAppWidgetInfo>();
            ArrayList<LauncherAppWidgetInfo> otherAppWidgets =
                    new ArrayList<LauncherAppWidgetInfo>();
            HashMap<Long, FolderInfo> currentFolders = new HashMap<Long, FolderInfo>();
            HashMap<Long, FolderInfo> otherFolders = new HashMap<Long, FolderInfo>();

            // Separate the items that are on the current screen, and all the other remaining items
            filterCurrentWorkspaceItems(currentScreen, workspaceItems, currentWorkspaceItems,
                    otherWorkspaceItems);
            filterCurrentAppWidgets(currentScreen, appWidgets, currentAppWidgets,
                    otherAppWidgets);
            filterCurrentFolders(currentScreen, itemsIdMap, folders, currentFolders,
                    otherFolders);
            sortWorkspaceItemsSpatially(currentWorkspaceItems);
            sortWorkspaceItemsSpatially(otherWorkspaceItems);

            // Tell the workspace that we're about to start binding items
            r = new Runnable() {
                public void run() {
                    Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                    if (callbacks != null) {
                        callbacks.startBinding();
                    }
                }
            };
            runOnMainThread(r);

            // Load items on the current page
            bindWorkspaceItems(oldCallbacks, currentWorkspaceItems, currentAppWidgets,
                    currentFolders, null);
            if (isLoadingSynchronously) {
                r = new Runnable() {
                    public void run() {
                        Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                        if (callbacks != null) {
                            callbacks.onPageBoundSynchronously(currentScreen);
                        }
                    }
                };
                runOnMainThread(r);
            }

            // Load all the remaining pages (if we are loading synchronously, we want to defer this
            // work until after the first render)
            mDeferredBindRunnables.clear();
            bindWorkspaceItems(oldCallbacks, otherWorkspaceItems, otherAppWidgets, otherFolders,
                    (isLoadingSynchronously ? mDeferredBindRunnables : null));

            // Tell the workspace that we're done binding items
            r = new Runnable() {
                public void run() {
                    Callbacks callbacks = tryGetCallbacks(oldCallbacks);
                    if (callbacks != null) {
                        callbacks.finishBindingItems();
                    }

                    // If we're profiling, ensure this is the last thing in the queue.
                    if (DEBUG_LOADERS) {
                        Log.d(TAG, "bound workspace in "
                            + (SystemClock.uptimeMillis()-t) + "ms");
                    }

                    mIsLoadingAndBindingWorkspace = false;
                }
            };
            if (isLoadingSynchronously) {
                mDeferredBindRunnables.add(r);
            } else {
                runOnMainThread(r);
            }
        }

这段代码有很多需要解释的，本质就是app，widgets, folders获取并传给主界面。今天就分析到这里。后面还有很多，这次就分析到这里，

如有问题 ，欢迎指出 谢谢。O(∩_∩)O~