说明

Java获取时间点有：Date、Calendar、LocalDateTime。有个需求，根据某个时间获取所属的某个时刻点。

代码案例

import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Calendar;
import java.util.Date;

public class DateTest {

    public static void main(String[] args) {
        // 获取时间
        Date date = new Date();
        SimpleDateFormat dateFormat1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        System.out.println(dateFormat1.format(date));
        // 获取时间
        Calendar calendar = Calendar.getInstance();
        SimpleDateFormat dateFormat2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        System.out.println(dateFormat2.format(calendar.getTime()));
        // 获取时间
        LocalDateTime localDateTime = LocalDateTime.now();
        DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        System.out.println(dateFormatter.format(localDateTime));
        // 获取时间
        Calendar cal = Calendar.getInstance();
        int y = cal.get(Calendar.YEAR);
        int m = cal.get(Calendar.MONTH);
        int d = cal.get(Calendar.DATE);
        int h = cal.get(Calendar.HOUR_OF_DAY);
        int mi = cal.get(Calendar.MINUTE);
        int s = cal.get(Calendar.SECOND);
        System.out.println("现在时刻：" + y + "年" + m + "月" + d + "日" + h + "时" + mi + "分" + s + "秒");
    }

}

import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.util.Calendar;
import java.util.Date;

public final class DateUtils {

    /**
     * 获取当前时间的整点小时时间
     *
     * @return
     */
    public static Date getCurrentHourTime() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        return calendar.getTime();
    }

    /**
     * 获取当前时间的整点刻时间
     *
     * @return
     */
    public static Date getCurrentQuarterTime() {
        LocalDateTime localDateTime = LocalDateTime.now();
        int minute = localDateTime.getMinute();
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.MINUTE, (minute / 15) * 15);
        calendar.set(Calendar.SECOND, 0);
        return calendar.getTime();
    }

    /**
     * 获取当前时间的整点刻时间
     *
     * @return
     */
    public static Date getCurrentQuarterTime(LocalDateTime localDateTime) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.MINUTE, (localDateTime.getMinute() / 15) * 15);
        calendar.set(Calendar.SECOND, 0);
        return calendar.getTime();
    }

    /**
     * 获取当前时间的整点小时时间
     *
     * @return
     */
    public static Date getCurrentMinuteTime() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.SECOND, 0);
        return calendar.getTime();
    }

    /**
     * @param date
     * @return
     */
    public static String format(Date date) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return sdf.format(date);
    }

    public static void main(String[] args) {
        Date currentHourTime = getCurrentHourTime();
        System.out.println("整小时时间：" + currentHourTime);
        System.out.println("整小时时间：" + format(currentHourTime));
        Date currentQuarterTime = getCurrentQuarterTime();
        System.out.println("整刻钟时间：" + format(currentQuarterTime));
        System.out.println("整刻钟时间：" + format(currentQuarterTime));
        Date currentQuarterTime2 = getCurrentQuarterTime(LocalDateTime.now());
        System.out.println("整刻钟时间：" + format(currentQuarterTime2));
        System.out.println("整刻钟时间：" + format(currentQuarterTime2));
        Date currentMinuteTime = getCurrentMinuteTime();
        System.out.println("整分钟时间：" + currentMinuteTime);
        System.out.println("整分钟时间：" + format(currentMinuteTime));
    }

}