直接上代码，不做过多解释了

package testJava;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class IsEffectiveDate {
    public static void main(String[] args) throws ParseException {
        String format = "yy-mm-dd HH:mm:ss"; //时间格式这里可以自己随便改
        //下面这种就可以查看到毫秒
        System.out.println("当前时间：" + 
        new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss-SSS") .format(new Date() ));
        Date nowTime = new SimpleDateFormat(format).parse("2020-11-13 15:28:00");
        Date startTime = new SimpleDateFormat(format).parse("2020-11-13 15:27:00");
        Date endTime = new SimpleDateFormat(format).parse("2020-11-13 15:27:59");
        System.out.println(isEffectiveDate(nowTime, startTime, endTime));

    }
    /**
     *判断当前时间是否在时间区间内
     */
    private static boolean isEffectiveDate(Date nowTime, Date startTime, Date endTime) {
        if (nowTime.getTime() == startTime.getTime() || nowTime.getTime() == endTime.getTime()) {
            return true;
        }
        return nowTime.after(startTime) && nowTime.before(endTime);
    }
}

运行结果：