Android应用程序安装过程源代码分析（4）

        Step 12. PackageManagerService.scanPackageLI

        这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中：

class PackageManagerService extends IPackageManager.Stub {
    ......

    // Keys are String (package name), values are Package.  This also serves
    // as the lock for the global state.  Methods that must be called with
    // this lock held have the prefix "LP".
    final HashMap<String, PackageParser.Package> mPackages =
        new HashMap<String, PackageParser.Package>();

    ......

    // All available activities, for your resolving pleasure.
    final ActivityIntentResolver mActivities =
    new ActivityIntentResolver();

    // All available receivers, for your resolving pleasure.
    final ActivityIntentResolver mReceivers =
        new ActivityIntentResolver();

    // All available services, for your resolving pleasure.
    final ServiceIntentResolver mServices = new ServiceIntentResolver();

    // Keys are String (provider class name), values are Provider.
    final HashMap<ComponentName, PackageParser.Provider> mProvidersByComponent =
        new HashMap<ComponentName, PackageParser.Provider>();

    ......

    private PackageParser.Package scanPackageLI(PackageParser.Package pkg,
            int parseFlags, int scanMode, long currentTime) {
        ......

        synchronized (mPackages) {
            ......

            // Add the new setting to mPackages
            mPackages.put(pkg.applicationInfo.packageName, pkg);

            ......

            int N = pkg.providers.size();
            int i;
            for (i=0; i<N; i++) {
                PackageParser.Provider p = pkg.providers.get(i);
                p.info.processName = fixProcessName(pkg.applicationInfo.processName,
                    p.info.processName, pkg.applicationInfo.uid);
                mProvidersByComponent.put(new ComponentName(p.info.packageName,
                    p.info.name), p);

                ......
            }

            N = pkg.services.size();
            for (i=0; i<N; i++) {
                PackageParser.Service s = pkg.services.get(i);
                s.info.processName = fixProcessName(pkg.applicationInfo.processName,
                    s.info.processName, pkg.applicationInfo.uid);
                mServices.addService(s);

                ......
            }

            N = pkg.receivers.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Activity a = pkg.receivers.get(i);
                a.info.processName = fixProcessName(pkg.applicationInfo.processName,
                    a.info.processName, pkg.applicationInfo.uid);
                mReceivers.addActivity(a, "receiver");

                ......
            }

            N = pkg.activities.size();
            for (i=0; i<N; i++) {
                PackageParser.Activity a = pkg.activities.get(i);
                a.info.processName = fixProcessName(pkg.applicationInfo.processName,
                    a.info.processName, pkg.applicationInfo.uid);
                mActivities.addActivity(a, "activity");

                ......
            }

            ......
        }

        ......

        return pkg;
    }

    ......
}

        这个函数主要就是把前面解析应用程序得到的package、provider、service、receiver和activity等信息保存在PackageManagerService服务中了。

        这样，在Android系统启动的时候安装应用程序的过程就介绍完了，但是，这些应用程序只是相当于在PackageManagerService服务注册好了，如果我们想要在Android桌面上看到这些应用程序，还需要有一个Home应用程序，负责从PackageManagerService服务中把这些安装好的应用程序取出来，并以友好的方式在桌面上展现出来，例如以快捷图标的形式。在Android系统中，负责把系统中已经安装的应用程序在桌面中展现出来的Home应用程序就是Launcher了，在下一篇文章中，我们将介绍Launcher是如何启动的以及它是如何从PackageManagerService服务中把系统中已经安装好的应用程序展现出来的，敬请期待。