android6.0 Launcher2应用解析

Posted 2020-08-09

在之前我们分析了android6.0系统在启动时安装应用程序的过程，这些应用程序安装好之后，Launcher应用就负责把它们在桌面上展示出来。

一、AMS启动Launcher

Launcher应用是在AMS的systemReady方法中直接调用startHomeActivityLocked启动的，下面是systemReady启动Launcher的代码。

startHomeActivityLocked(mCurrentUserId, "systemReady");

我们来看下这个函数，先调用了getHomeIntent方法来获取Intent，然后也是调用resolveActivityInfo函数从PKMS获取ActivityInfo，接着当进程没有启动的话，调用ActivityStackSupervisor的startHomeActivity函数

    boolean startHomeActivityLocked(int userId, String reason) {
        if (mFactoryTest == FactoryTest.FACTORY_TEST_LOW_LEVEL
                && mTopAction == null) {
            // We are running in factory test mode, but unable to find
            // the factory test app, so just sit around displaying the
            // error message and don't try to start anything.
            return false;
        }
        Intent intent = getHomeIntent();//获取intent
        ActivityInfo aInfo =
            resolveActivityInfo(intent, STOCK_PM_FLAGS, userId);//获取ActivityInfo
        if (aInfo != null) {
            intent.setComponent(new ComponentName(
                    aInfo.applicationInfo.packageName, aInfo.name));
            // Don't do this if the home app is currently being
            // instrumented.
            aInfo = new ActivityInfo(aInfo);
            aInfo.applicationInfo = getAppInfoForUser(aInfo.applicationInfo, userId);
            ProcessRecord app = getProcessRecordLocked(aInfo.processName,
                    aInfo.applicationInfo.uid, true);
            if (app == null || app.instrumentationClass == null) {//进程没有启动调用
                EventLog.writeEvent(EventLogTags.AM_PROC_START,"AMS -> startHomeActivityLocked startHomeActivity then startActivityLock : "+ aInfo.processName);
                intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK);
                mStackSupervisor.startHomeActivity(intent, aInfo, reason);
            }
        }

        return true;
    }

我们先来看看getHomeIntent这个函数。

    Intent getHomeIntent() {
        Intent intent = new Intent(mTopAction, mTopData != null ? Uri.parse(mTopData) : null);
        intent.setComponent(mTopComponent);
        if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) {
            intent.addCategory(Intent.CATEGORY_HOME);
        }
        return intent;
    }

然后我们来看下ActivityStackSupervisor的startHomeActivity函数，它也是调用了startActivityLocked来启动Activity的，在之前的博客分析过这个函数这里我们就不介绍了。

    void startHomeActivity(Intent intent, ActivityInfo aInfo, String reason) {
        moveHomeStackTaskToTop(HOME_ACTIVITY_TYPE, reason);
        startActivityLocked(null /* caller */, intent, null /* resolvedType */, aInfo,
                null /* voiceSession */, null /* voiceInteractor */, null /* resultTo */,
                null /* resultWho */, 0 /* requestCode */, 0 /* callingPid */, 0 /* callingUid */,
                null /* callingPackage */, 0 /* realCallingPid */, 0 /* realCallingUid */,
                0 /* startFlags */, null /* options */, false /* ignoreTargetSecurity */,
                false /* componentSpecified */,
                null /* outActivity */, null /* container */,  null /* inTask */);
        if (inResumeTopActivity) {
            // If we are in resume section already, home activity will be initialized, but not
            // resumed (to avoid recursive resume) and will stay that way until something pokes it
            // again. We need to schedule another resume.
            scheduleResumeTopActivities();
        }
    }

二、Launcher启动

接着我们来看下Launcher的AndroidManifest.xml，我们看下其主Activity有一个category为android.intent.category.HOME

    <application
        android:name="com.android.launcher2.LauncherApplication"
        android:label="@string/application_name"
        android:icon="@mipmap/ic_launcher_home"
        android:hardwareAccelerated="true"
        android:largeHeap="@bool/config_largeHeap"
        android:supportsRtl="true">
        <activity
            android:name="com.android.launcher2.Launcher"
            android:launchMode="singleTask"
            android:clearTaskOnLaunch="true"
            android:stateNotNeeded="true"
            android:resumeWhilePausing="true"
            android:theme="@style/Theme"
            android:windowSoftInputMode="adjustPan"
            android:screenOrientation="nosensor"> 
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.HOME" />
                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.MONKEY"/>
            </intent-filter>
        </activity>
        ......

在Launcher.java的onCreate函数中调用了mModel.startLoader函数

    protected void onCreate(Bundle savedInstanceState) {
        ......
        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());
            }
        }
        ......

startLoader函数会post一个Runnable消息，我们来看下它的run方法

    public void startLoader(boolean isLaunching, int synchronousBindPage) {
        synchronized (mLock) {
            if (DEBUG_LOADERS) {
                Log.d(TAG, "startLoader isLaunching=" + isLaunching);
            }

            // Clear any deferred bind-runnables from the synchronized load process
            // We must do this before any loading/binding is scheduled below.
            mDeferredBindRunnables.clear();

            // Don't bother to start the thread if we know it's not going to do anything
            if (mCallbacks != null && mCallbacks.get() != null) {
                // If there is already one running, tell it to stop.
                // also, don't downgrade isLaunching if we're already running
                isLaunching = isLaunching || stopLoaderLocked();
                mLoaderTask = new LoaderTask(mApp, isLaunching);
                if (synchronousBindPage > -1 && mAllAppsLoaded && mWorkspaceLoaded) {
                    mLoaderTask.runBindSynchronousPage(synchronousBindPage);
                } else {
                    sWorkerThread.setPriority(Thread.NORM_PRIORITY);
                    sWorker.post(mLoaderTask);
                }
            }
        }
    }

在它的run方法中会调用loadAndBindAllApps函数，在loadAndBindAllApps函数中又会调用loadAllAppsByBatch函数

        public void run() {
            synchronized (mLock) {
                mIsLoaderTaskRunning = true;
            }

           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) {
                    if (DEBUG_LOADERS) Log.d(TAG, "Setting thread priority to " +
                            (mIsLaunching ? "DEFAULT" : "BACKGROUND"));
                    Process.setThreadPriority(mIsLaunching
                            ? Process.THREAD_PRIORITY_DEFAULT : Process.THREAD_PRIORITY_BACKGROUND);
                }

                // First step. Load workspace first, this is necessary since adding of apps from
                // managed profile in all apps is deferred until onResume. See http://b/17336902.
                if (loadWorkspaceFirst) {
                    if (DEBUG_LOADERS) Log.d(TAG, "step 1: loading workspace");
                    loadAndBindWorkspace();
                } else {
                    Log.d(TAG, "step 1: special: loading  all apps");
                    loadAndBindAllApps();
                }

我们先来看下loadAndBindAllApps函数，这个函数先进入while循环，然后调用了LauncherApps的getActivityList函数，后面又会调用callbacks的bindAllApplications

        private void loadAllAppsByBatch() {
            final long t = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
            ......
            mBgAllAppsList.clear();
            final int profileCount = profiles.size();
            for (int p = 0; p < profileCount; p++) {
                ......
                while (i < N && !mStopped) {
                    if (i == 0) {
                        final long qiaTime = DEBUG_LOADERS ? SystemClock.uptimeMillis() : 0;
                        apps = mLauncherApps.getActivityList(null, user);
                        ......
                        
                     
                    mHandler.post(new Runnable() {
                        public void run() {
                            final long t = SystemClock.uptimeMillis();
                            if (callbacks != null) {
                                if (firstProfile) {
                                    callbacks.bindAllApplications(added);
                                } else {
                                    callbacks.bindAppsAdded(added);
                                }
                                if (DEBUG_LOADERS) {
                                    Log.d(TAG, "bound " + added.size() + " apps in "
                                        + (SystemClock.uptimeMillis() - t) + "ms");
                                }
                            } else {
                                Log.i(TAG, "not binding apps: no Launcher activity");
                            }
                        }
                    });
                    ......

我们先来看LauncherApps的getActivityList函数，它先用mService成员变量调用getLauncherActivities函数获取到list<ResolveInfo>，然后封装在ArrayList<LauncherActivityInfo> 中。

    public List<LauncherActivityInfo> getActivityList(String packageName, UserHandle user) {
        List<ResolveInfo> activities = null;
        try {
            activities = mService.getLauncherActivities(packageName, user);
        } catch (RemoteException re) {
            throw new RuntimeException("Failed to call LauncherAppsService");
        }
        if (activities == null) {
            return Collections.EMPTY_LIST;
        }
        ArrayList<LauncherActivityInfo> lais = new ArrayList<LauncherActivityInfo>();
        final int count = activities.size();
        for (int i = 0; i < count; i++) {
            ResolveInfo ri = activities.get(i);
            long firstInstallTime = 0;
            try {
                firstInstallTime = mPm.getPackageInfo(ri.activityInfo.packageName,
                    PackageManager.GET_UNINSTALLED_PACKAGES).firstInstallTime;
            } catch (NameNotFoundException nnfe) {
                // Sorry, can't find package
            }
            LauncherActivityInfo lai = new LauncherActivityInfo(mContext, ri, user,
                    firstInstallTime);
            if (DEBUG) {
                Log.v(TAG, "Returning activity for profile " + user + " : "
                        + lai.getComponentName());
            }
            lais.add(lai);
        }
        return lais;
    }

其service是class LauncherAppsImpl extends ILauncherApps.Stub 下面是getLauncherActivities函数，肯定也是通过PKMS来获取相关Activity的ResolveInfo的。

        @Override
        public List<ResolveInfo> getLauncherActivities(String packageName, UserHandle user)
                throws RemoteException {
            ensureInUserProfiles(user, "Cannot retrieve activities for unrelated profile " + user);
            if (!isUserEnabled(user)) {
                return new ArrayList<ResolveInfo>();
            }

            final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
            mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
            mainIntent.setPackage(packageName);
            long ident = Binder.clearCallingIdentity();
            try {
                List<ResolveInfo> apps = mPm.queryIntentActivitiesAsUser(mainIntent, 0 /* flags */,
                        user.getIdentifier());
                return apps;
            } finally {
                Binder.restoreCallingIdentity(ident);
            }
        }

最后回调Launcher.java的bindAllApplications函数，最后在这个函数中可以在桌面上展示系统中所有的应用程序了。

    public void bindAllApplications(final ArrayList<ApplicationInfo> apps) {
        Runnable setAllAppsRunnable = new Runnable() {
            public void run() {
                if (mAppsCustomizeContent != null) {
                    mAppsCustomizeContent.setApps(apps);
                }
            }
        };

        // Remove the progress bar entirely; we could also make it GONE
        // but better to remove it since we know it's not going to be used
        View progressBar = mAppsCustomizeTabHost.
            findViewById(R.id.apps_customize_progress_bar);
        if (progressBar != null) {
            ((ViewGroup)progressBar.getParent()).removeView(progressBar);

            // We just post the call to setApps so the user sees the progress bar
            // disappear-- otherwise, it just looks like the progress bar froze
            // which doesn't look great
            mAppsCustomizeTabHost.post(setAllAppsRunnable);
        } else {
            // If we did not initialize the spinner in onCreate, then we can directly set the
            // list of applications without waiting for any progress bars views to be hidden.
            setAllAppsRunnable.run();
        }
    }

三、显示应用图标

我们再来看下Launcher的onClick函数，当调用showWorkspace可以显示所有应用的图标。

    public void onClick(View v) {
        // Make sure that rogue clicks don't get through while allapps is launching, or after the
        // view has detached (it's possible for this to happen if the view is removed mid touch).
        if (v.getWindowToken() == null) {
            return;
        }

        if (!mWorkspace.isFinishedSwitchingState()) {
            return;
        }

        Object tag = v.getTag();
        if (tag instanceof ShortcutInfo) {
            // Open shortcut
            final Intent intent = ((ShortcutInfo) tag).intent;
            int[] pos = new int[2];
            v.getLocationOnScreen(pos);
            intent.setSourceBounds(new Rect(pos[0], pos[1],
                    pos[0] + v.getWidth(), pos[1] + v.getHeight()));

            boolean success = startActivitySafely(v, intent, tag);

            if (success && v instanceof BubbleTextView) {
                mWaitingForResume = (BubbleTextView) v;
                mWaitingForResume.setStayPressed(true);
            }
        } else if (tag instanceof FolderInfo) {
            if (v instanceof FolderIcon) {
                FolderIcon fi = (FolderIcon) v;
                handleFolderClick(fi);
            }
        } else if (v == mAllAppsButton) {
            if (isAllAppsVisible()) {
                showWorkspace(true);
            } else {
                onClickAllAppsButton(v);
            }
        }
    }

在showWorkspace中会显示所有的图标

    void showWorkspace(boolean animated, Runnable onCompleteRunnable) {
        if (mState != State.WORKSPACE) {
            boolean wasInSpringLoadedMode = (mState == State.APPS_CUSTOMIZE_SPRING_LOADED);
            mWorkspace.setVisibility(View.VISIBLE);
            hideAppsCustomizeHelper(State.WORKSPACE, animated, false, onCompleteRunnable);

            // Show the search bar (only animate if we were showing the drop target bar in spring
            // loaded mode)
            if (mSearchDropTargetBar != null) {
                mSearchDropTargetBar.showSearchBar(wasInSpringLoadedMode);
            }

            // We only need to animate in the dock divider if we're going from spring loaded mode
            showDockDivider(animated && wasInSpringLoadedMode);

            // Set focus to the AppsCustomize button
            if (mAllAppsButton != null) {
                mAllAppsButton.requestFocus();
            }
        }

        mWorkspace.flashScrollingIndicator(animated);

        // Change the state *after* we've called all the transition code
        mState = State.WORKSPACE;

        // Resume the auto-advance of widgets
        mUserPresent = true;
        updateRunning();

        // Send an accessibility event to announce the context change
        getWindow().getDecorView()
                .sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED);
    }

而点击应用图标，最终会调用Launcher.java的startActivitySafely来启动应用。这里调用的startActivity就是Activity的startActivity函数。

    boolean startActivitySafely(View v, Intent intent, Object tag) {
        boolean success = false;
        try {
            success = startActivity(v, intent, tag);
        } catch (ActivityNotFoundException e) {
            Toast.makeText(this, R.string.activity_not_found, Toast.LENGTH_SHORT).show();
            Log.e(TAG, "Unable to launch. tag=" + tag + " intent=" + intent, e);
        }
        return success;
    }