如何在android应用中利用service实现一个计时器功能

<&#63;xml version="1.0" encoding="utf-8"&#63;><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/self_driving_wait_ll" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:orientation="vertical"> <TextView  android:id="@+id/tv_time"  android:layout_width="wrap_content"  android:layout_height="wrap_content"  android:layout_centerInParent="true"  android:layout_marginTop="20.0dp"  android:gravity="center_horizontal"  android:text="00:00:00"  android:textSize="88.0sp" /> </LinearLayout></RelativeLayout>