Android 9.0 Launcher启动详解

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作者：Albert0211
链接：https://www.jianshu.com/p/0b273112cd7e
声明：本文已获Albert0211授权发表，转发等请联系原作者授权

Launcer作为一个独立的APP，从开始执行到加载完成的整个流程。

Launcher.png

启动核心代码如下：

/packages/apps/Launcher3/src/com/android/launcher3/Launcher.java

@Override
    protected void onCreate(Bundle savedInstanceState) {
        Log.d(TAG,"onCreate =======");
       
        ....
      

        mModel = app.setLauncher(this);
        initDeviceProfile(app.getInvariantDeviceProfile());

        mSharedPrefs = Utilities.getPrefs(this);
        mIconCache = app.getIconCache();
        mAccessibilityDelegate = new LauncherAccessibilityDelegate(this);

        mDragController = new DragController(this);
        mAllAppsController = new AllAppsTransitionController(this);
        mStateManager = new LauncherStateManager(this);
        UiFactory.onCreate(this);

        mAppWidgetManager = AppWidgetManagerCompat.getInstance(this);

        mAppWidgetHost = new LauncherAppWidgetHost(this);
        mAppWidgetHost.startListening();
        mLauncherView = LayoutInflater.from(this).inflate(R.layout.launcher, null);
  
        ...

        setupViews();

        ...

      int currentScreen = PagedView.INVALID_RESTORE_PAGE;
        if (savedInstanceState != null) {
            currentScreen = savedInstanceState.getInt(RUNTIME_STATE_CURRENT_SCREEN, currentScreen);
        }
        Log.e(TAG,"currentScreen :"+currentScreen+","+", loader bind: "+mModel.startLoader(currentScreen)+", internalStateHandled: "+internalStateHandled);

        if (!mModel.startLoader(currentScreen)) {
            if (!internalStateHandled) {
                // If we are not binding synchronously, show a fade in animation when
                // the first page bind completes.
                mDragLayer.getAlphaProperty(ALPHA_INDEX_LAUNCHER_LOAD).setValue(0);
            }
        } else {
            // Pages bound synchronously.
            mWorkspace.setCurrentPage(currentScreen);

            setWorkspaceLoading(true);
        }


        ...

    }

其中，setupViews，查找所有的view，并配置，

private void setupViews() {

         ...

        // default state, otherwise we will update to the wrong offsets in RTL
        mWorkspace.lockWallpaperToDefaultPage();
        mWorkspace.bindAndInitFirstWorkspaceScreen(null /* recycled qsb */);
        mDragController.addDragListener(mWorkspace);

        // Get the search/delete/uninstall bar
        mDropTargetBar = mDragLayer.findViewById(R.id.drop_target_bar);
        // Setup Apps
        mAppsView = findViewById(R.id.apps_view);
        // Setup the drag controller (drop targets have to be added in reverse order in priority)
        mDragController.setMoveTarget(mWorkspace);
        mDropTargetBar.setup(mDragController);

        mAllAppsController.setupViews(mAppsView);
    }

1、packages/apps/Launcher3/src/com/android/launcher3/LauncherAppState.java

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

2、/packages/apps/Launcher3/src/com/android/launcher3/LauncherModel.java

其中 Launcer 实现了 Callbacks 接口，

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

3、/packages/apps/Launcher3/src/com/android/launcher3/Launcher.java

 initDeviceProfile(app.getInvariantDeviceProfile());

4、/packages/apps/Launcher3/src/com/android/launcher3/LauncherAppWidgetHost.java

  @Override
    public void startListening() {
        
      ...

        try {
            super.startListening();
        } catch (Exception e) {
            if (!Utilities.isBinderSizeError(e)) {
                throw new RuntimeException(e);
            }
            // We're willing to let this slide. The exception is being caused by the list of
            // RemoteViews which is being passed back. The startListening relationship will
            // have been established by this point, and we will end up populating the
            // widgets upon bind anyway. See issue 14255011 for more context.
        }

        // We go in reverse order and inflate any deferred widget
        for (int i = mViews.size() - 1; i >= 0; i--) {
            LauncherAppWidgetHostView view = mViews.valueAt(i);
            if (view instanceof DeferredAppWidgetHostView) {
                view.reInflate();
            }
        }
    }

5-6、 /packages/apps/Launcher3/src/com/android/launcher3/Launcher.java

 private void setupViews() {
      
        ...
        mWorkspace = mDragLayer.findViewById(R.id.workspace);
        mWorkspace.initParentViews(mDragLayer);
        mOverviewPanel = findViewById(R.id.overview_panel);
        mOverviewPanelContainer = findViewById(R.id.overview_panel_container);
        mHotseat = findViewById(R.id.hotseat);
        mHotseatSearchBox = findViewById(R.id.search_container_hotseat);
           
        ...

        mWorkspace.setup(mDragController);
        // Until the workspace is bound, ensure that we keep the wallpaper offset locked to the
        // default state, otherwise we will update to the wrong offsets in RTL
        mWorkspace.lockWallpaperToDefaultPage();
        mWorkspace.bindAndInitFirstWorkspaceScreen(null /* recycled qsb */);
       
        ...
    }

7-8、/packages/apps/Launcher3/src/com/android/launcher3/LauncherModel.java

  public boolean startLoader(int synchronousBindPage) {
        // Enable queue before starting loader. It will get disabled in Launcher#finishBindingItems
        InstallShortcutReceiver.enableInstallQueue(InstallShortcutReceiver.FLAG_LOADER_RUNNING);
        synchronized (mLock) {
            // Don't bother to start the thread if we know it's not going to do anything
            if (mCallbacks != null && mCallbacks.get() != null) {
                
                ...

                if (mModelLoaded && !mIsLoaderTaskRunning) {
                    // Divide the set of loaded items into those that we are binding synchronously,
                    // and everything else that is to be bound normally (asynchronously).
                    loaderResults.bindWorkspace();
                    // For now, continue posting the binding of AllApps as there are other
                    // issues that arise from that.
                    loaderResults.bindAllApps();
                    loaderResults.bindDeepShortcuts();
                    loaderResults.bindWidgets();
                    return true;
                } else {
                    startLoaderForResults(loaderResults);
                }
            }
        }
        return false;
    }

 public void startLoaderForResults(LoaderResults results) {
        synchronized (mLock) {
            stopLoader();
            mLoaderTask = new LoaderTask(mApp, mBgAllAppsList, sBgDataModel, results);
            runOnWorkerThread(mLoaderTask);
        }
    }

9-14 /packages/apps/Launcher3/src/com/android/launcher3/model/LoaderTask.java

         ...

       TraceHelper.beginSection(TAG);
        try (LauncherModel.LoaderTransaction transaction = mApp.getModel().beginLoader(this)) {
            TraceHelper.partitionSection(TAG, "step 1.1: loading workspace");
            loadWorkspace();

            verifyNotStopped();
            TraceHelper.partitionSection(TAG, "step 1.2: bind workspace workspace");
            mResults.bindWorkspace();

            // Notify the installer packages of packages with active installs on the first screen.
            TraceHelper.partitionSection(TAG, "step 1.3: send first screen broadcast");
            sendFirstScreenActiveInstallsBroadcast();

            // Take a break
            TraceHelper.partitionSection(TAG, "step 1 completed, wait for idle");
            waitForIdle();
            verifyNotStopped();

            // second step
            TraceHelper.partitionSection(TAG, "step 2.1: loading all apps");
            loadAllApps();

            TraceHelper.partitionSection(TAG, "step 2.2: Binding all apps");
            verifyNotStopped();
            mResults.bindAllApps();

            verifyNotStopped();
            TraceHelper.partitionSection(TAG, "step 2.3: Update icon cache");
            updateIconCache();

            // Take a break
            TraceHelper.partitionSection(TAG, "step 2 completed, wait for idle");
            waitForIdle();
            verifyNotStopped();

            // third step   /home/meng/apinext_workspace
            TraceHelper.partitionSection(TAG, "step 3.1: loading deep shortcuts");
            loadDeepShortcuts();

            verifyNotStopped();
            TraceHelper.partitionSection(TAG, "step 3.2: bind deep shortcuts");
            mResults.bindDeepShortcuts();

            // Take a break
            TraceHelper.partitionSection(TAG, "step 3 completed, wait for idle");
            waitForIdle();
            verifyNotStopped();

            // fourth step
            TraceHelper.partitionSection(TAG, "step 4.1: loading widgets");
            mBgDataModel.widgetsModel.update(mApp, null);

            verifyNotStopped();
            TraceHelper.partitionSection(TAG, "step 4.2: Binding widgets");
            mResults.bindWidgets();

            transaction.commit();
        } catch (CancellationException e) {
            // Loader stopped, ignore
            TraceHelper.partitionSection(TAG, "Cancelled");
        }
        TraceHelper.endSection(TAG);

      ...

加载完成，会跳转到LoaderResults，进行绑定操作，

通过接口Callbacks 回调，返回Launcher。

    public void bindWorkspace() {
        Runnable r;

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

        // Save a copy of all the bg-thread collections
        ArrayList workspaceItems = new ArrayList<>();
        ArrayList appWidgets = new ArrayList<>();
        final ArrayList orderedScreenIds = new ArrayList<>();

        synchronized (mBgDataModel) {
            workspaceItems.addAll(mBgDataModel.workspaceItems);
            appWidgets.addAll(mBgDataModel.appWidgets);
            orderedScreenIds.addAll(mBgDataModel.workspaceScreens);
            mBgDataModel.lastBindId++;
        }

        final int currentScreen;
        {
            int currScreen = mPageToBindFirst != PagedView.INVALID_RESTORE_PAGE
                    ? mPageToBindFirst : callbacks.getCurrentWorkspaceScreen();
            if (currScreen >= orderedScreenIds.size()) {
                // There may be no workspace screens (just hotseat items and an empty page).
                currScreen = PagedView.INVALID_RESTORE_PAGE;
            }
            currentScreen = currScreen;
        }
        final boolean validFirstPage = currentScreen >= 0;
        final long currentScreenId =
                validFirstPage ? orderedScreenIds.get(currentScreen) : INVALID_SCREEN_ID;

        // Separate the items that are on the current screen, and all the other remaining items
        ArrayList currentWorkspaceItems = new ArrayList<>();
        ArrayList otherWorkspaceItems = new ArrayList<>();
        ArrayList currentAppWidgets = new ArrayList<>();
        ArrayList otherAppWidgets = new ArrayList<>();

        filterCurrentWorkspaceItems(currentScreenId, workspaceItems, currentWorkspaceItems,
                otherWorkspaceItems);
        filterCurrentWorkspaceItems(currentScreenId, appWidgets, currentAppWidgets,
                otherAppWidgets);
        sortWorkspaceItemsSpatially(currentWorkspaceItems);
        sortWorkspaceItemsSpatially(otherWorkspaceItems);

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

        // Bind workspace screens
        mUiExecutor.execute(new Runnable() {
            @Override
            public void run() {
                Callbacks callbacks = mCallbacks.get();
                if (callbacks != null) {
                    callbacks.bindScreens(orderedScreenIds);
                }
            }
        });

        Executor mainExecutor = mUiExecutor;
        // Load items on the current page.
        bindWorkspaceItems(currentWorkspaceItems, currentAppWidgets, mainExecutor);

        // In case of validFirstPage, only bind the first screen, and defer binding the
        // remaining screens after first onDraw (and an optional the fade animation whichever
        // happens later).
        // This ensures that the first screen is immediately visible (eg. during rotation)
        // In case of !validFirstPage, bind all pages one after other.
        final Executor deferredExecutor =
                validFirstPage ? new ViewOnDrawExecutor() : mainExecutor;

        mainExecutor.execute(new Runnable() {
            @Override
            public void run() {
                Callbacks callbacks = mCallbacks.get();
                if (callbacks != null) {
                    callbacks.finishFirstPageBind(
                            validFirstPage ? (ViewOnDrawExecutor) deferredExecutor : null);
                }
            }
        });

        bindWorkspaceItems(otherWorkspaceItems, otherAppWidgets, deferredExecutor);

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

        if (validFirstPage) {
            r = new Runnable() {
                public void run() {
                    Callbacks callbacks = mCallbacks.get();
                    if (callbacks != null) {
                        // We are loading synchronously, which means, some of the pages will be
                        // bound after first draw. Inform the callbacks that page binding is
                        // not complete, and schedule the remaining pages.
                        if (currentScreen != PagedView.INVALID_RESTORE_PAGE) {
                            callbacks.onPageBoundSynchronously(currentScreen);
                        }
                        callbacks.executeOnNextDraw((ViewOnDrawExecutor) deferredExecutor);
                    }
                }
            };
            mUiExecutor.execute(r);
        }
    }

11.2、bindAllApplications

13.2、bindDeepShortcuts

14.2、bindWidgets

处理逻辑类似，在此就不贴代码了。

有点不同是是loading widgets，图中的14.1、update(mApp, null)。加载逻辑在这个文件，

/packages/apps/Launcher3/src/com/android/launcher3/model/WidgetsModel.java。

加载完成后，执行 transaction.commit() 在/packages/apps/Launcher3/src/com/android/launcher3/LauncherModel.java

 public void commit() {
            synchronized (mLock) {
                // Everything loaded bind the data.
                mModelLoaded = true;
            }
        }

然后,Launcher将数据赋值给各种View。

总结：

启动Launcher后，通过LauncherModel控制加载逻辑，LoaderTask开启线程加载数据，LoaderResults进行数据绑定的处理，最后将数据返回给Launcher处理。

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1 安卓 9.0 适配方案和踩坑
2 全栈级别梳理-Android系统启动流程
3 Android进程启动与Activity显示
4 如何统计Android App启动时间
5 Android:手把手教你如何优雅的实现APP启动速度优化

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