Android使用Handler+postDelayed实现简单计时器

我们在开发中会时常用到计时器，比如计算我们的APP工作的时长，下面介绍两种实现方案。

一、使用Handler+postDelayed实现计时器

先看效果图：

实现的代码：

public class MainActivity extends AppCompatActivity {    protected Button btnStart;    protected Button btnEnd;    static TextView tvWorkTime;    static Handler timeHandler = new Handler();    static Date beginDate = null;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        super.setContentView(R.layout.activity_main);        initView();    }    private void initView() {        btnStart = (Button) findViewById(R.id.btn_start);        btnEnd = (Button) findViewById(R.id.btn_end);        tvWorkTime = (TextView) findViewById(R.id.tv_work_time);    }    public void start(View view) {        btnStart.setVisibility(View.GONE);        btnEnd.setVisibility(View.VISIBLE);        beginDate = new Date();        timeHandler.postDelayed(runnable, 1000);    }    public void end(View view) {        btnStart.setVisibility(View.VISIBLE);        btnEnd.setVisibility(View.GONE);        timeHandler.removeCallbacks(runnable);    }    static Runnable runnable = new Runnable() {        @Override        public void run() {            TimeUtils(beginDate, new Date());            timeHandler.postDelayed(this, 1000);        }    };    public static void TimeUtils(Date beginDate, Date endDate){        SimpleDateFormat dfs = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");        long between = 0;        Date begin = null;        Date end = null;        try {            begin = dfs.parse(datetimeToString(beginDate));            end = dfs.parse(datetimeToString(endDate));            between = (end.getTime() - begin.getTime());// 得到两者的毫秒数        } catch (ParseException e) {            e.printStackTrace();        }        long day = between / (24 * 60 * 60 * 1000);        long hour = (between / (60 * 60 * 1000) - day * 24);        long min = ((between / (60 * 1000)) - day * 24 * 60 - hour * 60);        long s = (between / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);        tvWorkTime.setText("工作时长：" + hour + " : " + min + " : " + s);    }    public static String datetimeToString(Date date) {        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");        return sdf.format(date);    }}

布局文件：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:id="@+id/btn_start"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerVertical="true"        android:layout_marginLeft="30dp"        android:layout_marginTop="20dp"        android:background="@drawable/button"        android:onClick="start"        android:text="开始计时"        android:textSize="24sp"/>    <Button        android:id="@+id/btn_end"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerVertical="true"        android:layout_marginLeft="30dp"        android:layout_marginTop="20dp"        android:background="@drawable/button"        android:onClick="end"        android:visibility="gone"        android:text="结束计时"        android:textSize="24sp"/>    <TextView        android:id="@+id/tv_work_time"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="工作时长：0 : 0 : 0"        android:layout_marginTop="30dp"        android:layout_marginLeft="20dp"        android:textSize="20sp"        android:layout_alignParentBottom="true"        android:layout_marginBottom="12dp"/></LinearLayout>

按钮样式：

<?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:state_pressed="false">        <shape android:shape="rectangle" >            <solid android:color="#0FFFFF" />            <corners android:radius="15dip" />            <padding android:bottom="10dp" android:left="10dp" android:right="10dp" android:top="10dp" />        </shape>    </item>    <item android:state_pressed="true">        <shape android:shape="rectangle">            <solid android:color="#FFFF0F" />            <corners android:radius="15dip" />        </shape>    </item></selector>

二、使用Chronometer实现计时器

public class Main2Activity extends AppCompatActivity {    protected Chronometer timer;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        super.setContentView(R.layout.activity_main2);        initView();    }    private void initView() {        timer = (Chronometer) findViewById(R.id.timer);    }    public void start(View view){        timer.setBase(SystemClock.elapsedRealtime());//计时器清零        int hour = (int) ((SystemClock.elapsedRealtime() - timer.getBase()) / 1000 / 60);        timer.setFormat("0"+String.valueOf(hour)+":%s");        timer.start();    }    public void stop(View view){        timer.stop();    }}

布局文件：

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="start"        android:onClick="start"/>    <Button        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="stop"        android:onClick="stop"/>    <Chronometer        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:format="00:00:00"        android:textSize="20sp"        android:id="@+id/timer"/></LinearLayout>