Android 应用启动流程梳理

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Android 应用启动流程梳理（基于Android7.1.1）

Android启动流程

涉及的几个重要类

  • ActivityThread.java

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    /**
     * This manages the execution of the main thread in an
     * application process, scheduling and executing activities,
     * broadcasts, and other operations on it as the activity
     * manager requests.
     *
     * {@hide}
     */
     
     //关键类成员
     final ApplicationThread mAppThread = new ApplicationThread();
     final H mH = new H();
     Instrumentation mInstrumentation;
     final ArrayMap<String, WeakReference<LoadedApk>> mPackages = new ArrayMap<String, WeakReference<LoadedApk>>();
     //关键方法
     public static void main(String[] args){}
     private void attach(boolean system) {}
     public final void bindApplication(String processName, ApplicationInfo appInfo,
                    List<ProviderInfo> providers, ComponentName instrumentationName,
                    ProfilerInfo profilerInfo, Bundle instrumentationArgs,
                    IInstrumentationWatcher instrumentationWatcher,
                    IUiAutomationConnection instrumentationUiConnection, int debugMode,
                    boolean enableBinderTracking, boolean trackAllocation,
                    boolean isRestrictedBackupMode, boolean persistent, Configuration config,
                    CompatibilityInfo compatInfo, Map<String, IBinder> services, Bundle coreSettings) {
                AppBindData data = new AppBindData();
                data.processName = processName;
                data.appInfo = appInfo;
                data.providers = providers;
                data.instrumentationName = instrumentationName;
                data.instrumentationArgs = instrumentationArgs;
                data.instrumentationWatcher = instrumentationWatcher;
                data.instrumentationUiAutomationConnection = instrumentationUiConnection;
                data.debugMode = debugMode;
                data.enableBinderTracking = enableBinderTracking;
                data.trackAllocation = trackAllocation;
                data.restrictedBackupMode = isRestrictedBackupMode;
                data.persistent = persistent;
                data.config = config;
                data.compatInfo = compatInfo;
                data.initProfilerInfo = profilerInfo;
                sendMessage(H.BIND_APPLICATION, data); 
     }
     private void handleBindApplication(AppBindData data) {}

  • ActivityManagerService.java

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    //关键方法
    public final void attachApplication(IApplicationThread thread)

  • ApplicationLoaders.java

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    //关键变量
    private final ArrayMap<String, ClassLoader> mLoaders = new ArrayMap<String, ClassLoader>();//默认是PathClassLoader
    private static final ApplicationLoaders gApplicationLoaders = new ApplicationLoaders();
    //关键方法
    public static ApplicationLoaders getDefault() //被LoaderApk的createOrUpdateClassLoaderLocked方法调用

  • LoadedApk.java

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    /**
     * Local state maintained about a currently loaded .apk.
     *一个应用程序对应一个LoadedApk对象。它用来保存当前加载的APK包的各种信息，包括app安装路径、资源路径、用户数据保存路径、使用的类加载器、Application信  息等。
     * @hide
     */
    //关键变量
     private ClassLoader mClassLoader;
     private Application mApplication;
     private final ActivityThread mActivityThread
     private final ClassLoader mBaseClassLoader;
     //关键方法
     public Application makeApplication(boolean forceDefaultAppClass,Instrumentation instrumentation) {}
     public ClassLoader getClassLoader()
     private void createOrUpdateClassLoaderLocked(List<String> addedPaths)//被getClassLoader调用

  • Instrumentation类

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    /**
     * Base class for implementing application instrumentation code.  When running
     * with instrumentation turned on, this class will be instantiated for you
     * before any of the application code, allowing you to monitor all of the
     * interaction the system has with the application.  An Instrumentation
     * implementation is described to the system through an AndroidManifest.xml's
     * &lt;instrumentation&gt; tag.
     */

    //关键变量
    private ActivityThread mThread = null;
    private Context mInstrContext;
    private Context mAppContext;
    //关键方法
    public Application newApplication(ClassLoader cl, String className, Context context) //被LoadedApk的makeApplication方法调用
    static public Application newApplication(Class<?> clazz, Context context)

参考：https://shuwoom.com/?p=142