PowerManager.java

@SystemService(Context.POWER_SERVICE)
public final class PowerManager {

    final IPowerManager mService;

    public final class WakeLock {
        @UnsupportedAppUsage
        private int mFlags;
        @UnsupportedAppUsage
        private String mTag;
        private final String mPackageName;
        private final IBinder mToken;
        private final String mTraceName;

        WakeLock(int flags, String tag, String packageName) {
            // Create a token that uniquely identifies this wake lock.
            mToken = new Binder();
            mFlags = flags;
            mTag = tag;
            mPackageName = packageName;
            mTraceName = "WakeLock (" + mTag + ")";
        }

        public void acquire() {
            // Send the power manager service a request to acquire a wake
            // lock for the application. Include the token as part of the
            // request so that the power manager service can validate the
            // application's identity when it requests to release the wake
            // lock later on.
            synchronized (mToken) {
                try {
                    mService.acquireWakeLock(mToken, mFlags, mTag);
                } catch (RemoteException e) {
                    throw e.rethrowFromSystemServer();
                }
            }
        }

        public void release(int flags) {
            // Send the power manager service a request to release the
            // wake lock associated with 'mToken'.
            synchronized (mToken) {
                try {
                    mService.releaseWakeLock(mToken, flags);
                } catch (RemoteException e) {
                    throw e.rethrowFromSystemServer();
                }
            }
        }
    }

    public WakeLock newWakeLock(int levelAndFlags, String tag) {
        return new WakeLock(levelAndFlags, tag);
    }
}