APK 启动流程

冷启动

1. Launcher 点击App图标：
   Launcher.java

onclick():
startActivitySafely()
super.startActivity

2.Activity.java

Instrumentation.ActivityResult ar =
                mInstrumentation.execStartActivity(
                    this, mMainThread.getApplicationThread(), mToken, this,
                    intent, requestCode, options);

3. Instrumentation.java

  public ActivityResult execStartActivity(
            Context who, IBinder contextThread, IBinder token, Activity target,
            Intent intent, int requestCode, Bundle options) {
        IApplicationThread whoThread = (IApplicationThread) contextThread;  
        try {
            intent.migrateExtraStreamToClipData();
            intent.prepareToLeaveProcess(who);
            //ActivityManagerService
            int result = ActivityManager.getService()
                .startActivity(whoThread, who.getBasePackageName(), intent,
                        intent.resolveTypeIfNeeded(who.getContentResolver()),
                        token, target != null ? target.mEmbeddedID : null,
                        requestCode, 0, null, options);
            checkStartActivityResult(result, intent);
        } catch (RemoteException e) {
            throw new RuntimeException("Failure from system", e);
        }
        return null;
    }

4. ActivityManagerService.java

  mActivityStarter = new ActivityStarter(this, mStackSupervisor);
    protected ActivityStackSupervisor createStackSupervisor() {
        return new ActivityStackSupervisor(this, mHandler.getLooper());
    }

    final int startActivity(Intent intent, ActivityStackSupervisor.ActivityContainer container) {
         ....
        intent.addFlags(FORCE_NEW_TASK_FLAGS);
        return mActivityStarter.startActivityMayWait(null, -1, null, intent, mimeType, null, null,
                null, null, 0, 0, null, null, null, null, false, userId, container, null,
                "startActivity");
    }

5.ActivityStarter.java
ActivityStackSupervisor.java
Zygote进程孵化出新的应用进程后，通过反射执行ActivityThread类的main方法。在该方法里会先准备好Looper和消息队列，然后调用attach方法将应用进程绑定到AMS，然后进入loop循环，不断地读取消息队列里的消息，并分发消息。
//ActivityThread

public static void main(String[] args) {
``````
//准备主线程的Looper，分析Handler,Looper
Looper.prepareMainLooper();

//创建当前进程的ActivityThread
ActivityThread thread = new ActivityThread();

//将该进程绑定到AMS
thread.attach(false);

if (sMainThreadHandler == null) {
//保存进程对应的主线程Handler
    sMainThreadHandler = thread.getHandler();
}

``````
//进入主线程的消息循环
Looper.loop();

``````

}

//上面说过，ApplicationThread是ActivityThread用来与AMS通讯的中介
final ApplicationThread mAppThread = new ApplicationThread();

private void attach(boolean system) {
if (!system) {
final IActivityManager mgr = ActivityManagerNative.getDefault();

    //调用AMS的attachApplication方法，将ApplicationThread对象绑定至ActivityManagerService
    //这样AMS就可以通过ApplicationThread代理对象控制应用进程

        mgr.attachApplication(mAppThread);
} else {
    ``````
}

}

https://blog.csdn.net/qian520ao/article/details/78156214

ActivityThread.java

handleLaunchActivity:
    performLaunchActivity:onCreate,onStart,onRestoreInstance
    handleResumeActivity: performResumeActivity   r.activity.performResume();