编辑代码

import java.util.Calendar;
import java.util.Date;
import java.util.Set;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;

class Main {
	public static void main(String[] args) throws ParseException {
        //JSRUN引擎2.0，支持多达30种语言在线运行，全仿真在线交互输入输出。
         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
         
        Date rankDate =  sdf.parse("2021-01-17 00:00:00");
		String dayKey = "";
		// 第几周
		Calendar calendar = Calendar.getInstance();
		calendar.setFirstDayOfWeek(Calendar.MONDAY);
		calendar.setTime(rankDate);
		dayKey += calendar.get(Calendar.WEEK_OF_YEAR);
        System.out.println(dayKey);

        Date date = new Date();
        System.out.println(date);
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.setTimeZone(TimeZone.getTimeZone("CST"));
        System.out.println(c.get(Calendar.WEEK_OF_YEAR));
	}
}