ActivityThread.java

源码位置：frameworks/base/core/java/android/app/ActivityThread.java

注意ActivityThread继承自ClientTransactionHandler类

• systemMain方法

  7187     @UnsupportedAppUsage
  7188     public static ActivityThread systemMain() {
  7189         // The system process on low-memory devices do not get to use hardware
  7190         // accelerated drawing, since this can add too much overhead to the
  7191         // process.
  7192         if (!ActivityManager.isHighEndGfx()) {
  7193             ThreadedRenderer.disable(true);
  7194         } else {
  7195             ThreadedRenderer.enableForegroundTrimming();
  7196         }
  7197         ActivityThread thread = new ActivityThread();
  7198         thread.attach(true, 0);
  7199         return thread;
  7200     }

  此方法除了SystemServer.java会调用，frameworks/base/cmds/media/src/com/android/commands/media/Media.java也会调用到。

• attach方法

  7111     @UnsupportedAppUsage
  7112     private void attach(boolean system, long startSeq) {
  7113         sCurrentActivityThread = this;
  7114         mSystemThread = system;
  7115         if (!system) {
              ...
  7147         } else {
  7148             // Don't set application object here -- if the system crashes,
  7149             // we can't display an alert, we just want to die die die.
  7150             android.ddm.DdmHandleAppName.setAppName("system_process",
  7151                     UserHandle.myUserId());
  7152             try {
  7153                 mInstrumentation = new Instrumentation();
  7154                 mInstrumentation.basicInit(this);
  7155                 ContextImpl context = ContextImpl.createAppContext(
  7156                         this, getSystemContext().mPackageInfo);
  7157                 mInitialApplication = context.mPackageInfo.makeApplication(true, null);
  7158                 mInitialApplication.onCreate();
  7159             } catch (Exception e) {
  7160                 throw new RuntimeException(
  7161                         "Unable to instantiate Application():" + e.toString(), e);
  7162             }
  7163         }

• getSystemContext方法

  2390     @UnsupportedAppUsage
  2391     public ContextImpl getSystemContext() {
  2392         synchronized (this) {
  2393             if (mSystemContext == null) {
  2394                 mSystemContext = ContextImpl.createSystemContext(this);
  2395             }
  2396             return mSystemContext;
  2397         }
  2398     }

• getSystemUiContext

  2400     public ContextImpl getSystemUiContext() {
  2401         synchronized (this) {
  2402             if (mSystemUiContext == null) {
  2403                 mSystemUiContext = ContextImpl.createSystemUiContext(getSystemContext());
  2404             }
  2405             return mSystemUiContext;
  2406         }
  2407     }