Android SystemServer学习之二

在Sytem Server运行时，会启动多个Java线程。第一个线程用于其它Service的消息处理，第二个线程用于ActivityManagerService和ActivityThread的消息处理，第三个用于WindowManagerService及KeyGuard TokenWatcher的消息处理。

ActivityManagerService.java

public final class ActivityManagerService extends ActivityManagerNative
        implements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {
    final Handler mHandler = new Handler() {

WindowManagerService.java

public class WindowManagerService extends IWindowManager.Stub implements Watchdog.Monitor {
    H mH = new H();
    final TokenWatcher mKeyguardTokenWatcher = new TokenWatcher(
            new Handler(), "WindowManagerService.mKeyguardTokenWatcher") { ...
    }
    private final class H extends Handler {

ActivityThread.java

public final class ActivityThread { ...
    final H mH = new H();

    public static final void main(String[] args) {
        SamplingProfilerIntegration.start();

        Process.setArgV0("<pre-initialized>");

        Looper.prepareMainLooper();
        if (sMainThreadHandler == null) {
            sMainThreadHandler = new Handler();
        }...
    }

    private final class H extends Handler {