用Android实现京东秒杀功能详解

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".SeckillActivity">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:gravity="center"
        android:text="仿京东秒杀"
        android:textColor="@color/black"
        android:textSize="20sp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/tv_screening"
            android:layout_width="100dp"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="几点场:"
            android:textColor="@color/black"
            android:textSize="15sp" />

        <TextView
            android:id="@+id/tv_hours"
            android:layout_width="50dp"
            android:layout_height="40dp"
            android:background="@drawable/time_back"
            android:gravity="center"
            android:text="00"
            android:textColor="@color/white"
            android:textSize="15sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=":"
            android:textColor="#fd5343"
            android:textSize="15sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/tv_minutes"
            android:layout_width="50dp"
            android:layout_height="40dp"
            android:background="@drawable/time_back"
            android:gravity="center"
            android:text="00"
            android:textColor="@color/white"
            android:textSize="15sp" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=":"
            android:textColor="#fd5343"
            android:textSize="15sp"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/tv_second"
            android:layout_width="50dp"
            android:layout_height="40dp"
            android:background="@drawable/time_back"
            android:gravity="center"
            android:text="00"
            android:textColor="@color/white"
            android:textSize="15sp" />
    </LinearLayout>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="#fd5343" />
    <corners android:radius="10dp" />
</shape>

public class SeckillActivity extends AppCompatActivity {
    //秒杀场次
    private TextView tv_screening;
    //2个小时一个秒杀场次,距离秒杀结束剩余多少小时
    private TextView tv_hours;
    //剩余分钟数
    private TextView tv_minutes;
    //剩余秒数
    private TextView tv_second;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_seckill);
        tv_screening = findViewById(R.id.tv_screening);
        tv_hours = findViewById(R.id.tv_hours);
        tv_minutes = findViewById(R.id.tv_minutes);
        tv_second = findViewById(R.id.tv_second);

        //计算秒杀场次,两个小时一个场次
        handler.sendEmptyMessage(0x00);
    }

    Handler handler = new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(@NonNull Message msg) {
            if (msg.what == 0x00) {
                //设置时间
                mkTime();
            }

            handler.sendEmptyMessageDelayed(0x00, 1000);
            return true;
        }
    });

    private void mkTime() {
        try {
            //使用给定的模式解析日期
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

            StringBuilder stringBuilder = new StringBuilder();
            String format = sdf.format(new Date());
            //获取当前的年月日
            String substring = format.substring(0, 11);
            stringBuilder.append(substring);

            //获取日历对象
            Calendar calendar = Calendar.getInstance();
            //获取一天中当前的小时数 24小时制的
            int hours = calendar.get(Calendar.HOUR_OF_DAY);
            //获取秒杀场次
            if (hours % 2 == 0) {
                tv_screening.setText(hours + "点场");
                stringBuilder.append(hours + 2);
            } else {
                tv_screening.setText((hours - 1) + "点场");
                stringBuilder.append(hours + 1);
            }
            stringBuilder.append(":00:00");
            Date sessionDate = sdf.parse(stringBuilder.toString());
            //获取秒杀场次+两个小时 的时间戳
            long sessionDateTime = sessionDate.getTime();

            //获取当前时间的时间戳
            Date date = new Date();
            long millisecond = date.getTime();

            //间隔时间戳
            long timestampMillisecond = sessionDateTime - millisecond;

            //剩余小时数
            long hour = timestampMillisecond / (1000 * 60 * 60);
            //剩余分钟数
            long minute = (timestampMillisecond - hour * (1000 * 60 * 60)) / (1000 * 60);
            //第①种方法： 获得剩余秒数
//            long second = (timestampMillisecond - hour * (1000 * 60 * 60) - minute * (1000 * 60)) / 1000;

            //第②种方法： 获得剩余秒数
            //取余数 得到的也是毫秒数
            long test = timestampMillisecond % (60 * 1000);
            //剩余的秒数 Math.round按照四舍五入返回最接近参数的int型整数
            long second = Math.round((float) (test / 1000));

            tv_hours.setText("0" + hour);

            if (minute >= 10) {
                tv_minutes.setText(minute + "");
            } else {
                tv_minutes.setText("0" + minute);
            }

            if (second >= 10) {
                tv_second.setText(second + "");
            } else {
                tv_second.setText("0" + second);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}