Activity的onCreate方法是怎样被调用的？

按前面源码分析的介绍，在Activity的onCreate方法中，添加如下的log：

android.util.Log.i("wztest", "Activity onCreate", new Exception());

重新编译后，启动联系人的一个页面，过滤log，有如下的输出：

05-24 21:06:43.034  2159  2159 I wztest  : Activity onCreate
05-24 21:06:43.034  2159  2159 I wztest  : java.lang.Exception
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.Activity.onCreate(Activity.java:990)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.support.v4.app.SupportActivity.onCreate(SupportActivity.java:66)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:290)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:84)
05-24 21:06:43.034  2159  2159 I wztest  : 	at com.android.contacts.activities.AppCompatTransactionSafeActivity.onCreate(AppCompatTransactionSafeActivity.java:33)
05-24 21:06:43.034  2159  2159 I wztest  : 	at com.android.contacts.AppCompatContactsActivity.onCreate(AppCompatContactsActivity.java:81)
05-24 21:06:43.034  2159  2159 I wztest  : 	at com.android.contacts.activities.PeopleActivity.onCreate(PeopleActivity.java:352)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.Activity.performCreate(Activity.java:7000)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.Activity.performCreate(Activity.java:6991)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.ActivityThread.-wrap11(Unknown Source:0)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.os.Handler.dispatchMessage(Handler.java:106)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.os.Looper.loop(Looper.java:164)
05-24 21:06:43.034  2159  2159 I wztest  : 	at android.app.ActivityThread.main(ActivityThread.java:6494)
05-24 21:06:43.034  2159  2159 I wztest  : 	at java.lang.reflect.Method.invoke(Native Method)
05-24 21:06:43.034  2159  2159 I wztest  : 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
05-24 21:06:43.034  2159  2159 I wztest  : 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

ActivityThread的handleLaunchActivity方法是如何被调用的？
通过搜索可知，由ApplicationThread的 scheduleLaunchActivity方法调用

ApplicationThread类定义如下，说明是其它进程跨进程调用过来的

private class ApplicationThread extends IApplicationThread.Stub

然后在，ApplicationThread的 scheduleLaunchActivity方法中添加一个log

android.util.Log.i("wztest", "ApplicationThread scheduleLaunchActivity", new Exception());

此时log输出如下：
在这里插入图片描述
可知是通过binder远程调用过来的，其实就是system_server调用过来的

ApplicationThread的 scheduleLaunchActivity方法如何被调用？
在源码中搜索，或者通过命令行来搜索

 grep "\.scheduleLaunchActivity" ./ -rn

-r 在多级目录中对文本进行递归搜索
-n 输出包含匹配字符串的行

可知和ActivityStackSupervisor类相关
在ActivityStackSupervisor的realStartActivityLocked方法，添加log

android.util.Log.i("wztest", "ActivityStackSupervisor realStartActivityLocked", new Exception());

log输出如下：
realStartActivityLocked

05-24 22:08:05.203  1547  1678 I wztest  : ActivityStackSupervisor realStartActivityLocked
05-24 22:08:05.203  1547  1678 I wztest  : java.lang.Exception
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityStackSupervisor.realStartActivityLocked(ActivityStackSupervisor.java:1315)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityStackSupervisor.startSpecificActivityLocked(ActivityStackSupervisor.java:1580)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityStack.resumeTopActivityInnerLocked(ActivityStack.java:2726)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityStack.resumeTopActivityUncheckedLocked(ActivityStack.java:2255)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityStackSupervisor.resumeFocusedStackTopActivityLocked(ActivityStackSupervisor.java:2094)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityStack.completePauseLocked(ActivityStack.java:1486)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityStack.activityPausedLocked(ActivityStack.java:1413)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityManagerService.activityPaused(ActivityManagerService.java:7441)
05-24 22:08:05.203  1547  1678 I wztest  : 	at android.app.IActivityManager$Stub.onTransact(IActivityManager.java:317)
05-24 22:08:05.203  1547  1678 I wztest  : 	at com.android.server.am.ActivityManagerService.onTransact(ActivityManagerService.java:2919)
05-24 22:08:05.203  1547  1678 I wztest  : 	at android.os.Binder.execTransact(Binder.java:697)
05-24 22:08:05.207  2167  2181 I wztest  : ApplicationThread scheduleLaunchActivity
05-24 22:08:05.207  2167  2181 I wztest  : java.lang.Exception
05-24 22:08:05.207  2167  2181 I wztest  : 	at android.app.ActivityThread$ApplicationThread.scheduleLaunchActivity(ActivityThread.java:788)
05-24 22:08:05.207  2167  2181 I wztest  : 	at android.app.IApplicationThread$Stub.onTransact(IApplicationThread.java:196)
05-24 22:08:05.207  2167  2181 I wztest  : 	at android.os.Binder.execTransact(Binder.java:697)
05-24 22:08:05.268  2167  2167 I wztest  : Activity onCreate
05-24 22:08:05.268  2167  2167 I wztest  : java.lang.Exception
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.Activity.onCreate(Activity.java:990)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.support.v4.app.SupportActivity.onCreate(SupportActivity.java:66)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:290)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.support.v7.app.AppCompatActivity.onCreate(AppCompatActivity.java:84)
05-24 22:08:05.268  2167  2167 I wztest  : 	at com.android.contacts.activities.AppCompatTransactionSafeActivity.onCreate(AppCompatTransactionSafeActivity.java:33)
05-24 22:08:05.268  2167  2167 I wztest  : 	at com.android.contacts.AppCompatContactsActivity.onCreate(AppCompatContactsActivity.java:81)
05-24 22:08:05.268  2167  2167 I wztest  : 	at com.android.contacts.activities.PeopleActivity.onCreate(PeopleActivity.java:352)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.Activity.performCreate(Activity.java:7000)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.Activity.performCreate(Activity.java:6991)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2732)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2857)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.ActivityThread.-wrap11(Unknown Source:0)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1590)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.os.Handler.dispatchMessage(Handler.java:106)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.os.Looper.loop(Looper.java:164)
05-24 22:08:05.268  2167  2167 I wztest  : 	at android.app.ActivityThread.main(ActivityThread.java:6495)
05-24 22:08:05.268  2167  2167 I wztest  : 	at java.lang.reflect.Method.invoke(Native Method)
05-24 22:08:05.268  2167  2167 I wztest  : 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
05-24 22:08:05.268  2167  2167 I wztest  : 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)