java日期相关

1.获取当前月第一天

    /**
     * 获取当前月的第一天
     *
     * @return
     */
    public static Date getFirstDayOfMonth() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_MONTH, 1);
        return calendar.getTime();

    }

2.获取当前月最后一天

/**
     * 获取当前月的最后一天
     *
     * @return
     */
    public static Date getLastDayOfMonth() {
        Calendar calendar = Calendar.getInstance();

        //方法一
        //calendar.add(Calendar.MONTH, 1);
        //calendar.set(Calendar.DAY_OF_MONTH, 1);
        //calendar.add(Calendar.DAY_OF_MONTH, -1);

        //方法二
        int actualMaximum = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
        calendar.set(Calendar.DAY_OF_MONTH, actualMaximum);

        return calendar.getTime();
    }

3.获取当前天的前N天或者后N天

　　     Date date = new Date();
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
        Calendar now = Calendar.getInstance();
        now.setTime(date);
　　　　　　//-1代表前一天，这里可以根据自己的需求调整
        now.add(Calendar.DAY_OF_MONTH, -1);
        String dateStr = sdf.format(now.getTime());

4.大礼包

public class TimeUtil {
    public static void main(String[] args) {
        System.out.println("当前小时开始："+getCurrentHourStartTime().toString());
        System.out.println("当前小时结束："+getCurrentHourEndTime().toString());
        System.out.println("当前天开始："+getCurrentDayStartTime().toString());
        System.out.println("当前天时结束："+getCurrentDayEndTime().toString());
        System.out.println("当前周开始："+getCurrentWeekDayStartTime().toString());
        System.out.println("当前周结束："+getCurrentWeekDayEndTime().toString());
        System.out.println("当前月开始："+getCurrentMonthStartTime().toString());
        System.out.println("当前月结束："+getCurrentMonthEndTime().toString());
        System.out.println("当前季度开始："+getCurrentQuarterStartTime().toString());
        System.out.println("当前季度结束："+getCurrentQuarterEndTime().toString());
        System.out.println("当前半年/后半年开始："+getHalfYearStartTime().toString());
        System.out.println("当前半年/后半年结束："+getHalfYearEndTime().toString());
        System.out.println("当前年开始："+getCurrentYearStartTime().toString());
        System.out.println("当前年结束："+getCurrentYearEndTime().toString());
    }
 
    /**
     * 获取 当前年、半年、季度、月、日、小时 开始结束时间
     */
 
    private final static SimpleDateFormat shortSdf = new SimpleDateFormat("yyyy-MM-dd");
    private final static SimpleDateFormat longHourSdf = new SimpleDateFormat("yyyy-MM-dd HH");;
    private final static SimpleDateFormat longSdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");;
 
 
    /**
     * 获得本周的第一天，周一
     *
     * @return
     */
    public static Date getCurrentWeekDayStartTime() {
        Calendar c = Calendar.getInstance();
        try {
            int weekday = c.get(Calendar.DAY_OF_WEEK) - 2;
            c.add(Calendar.DATE, -weekday);
            c.setTime(longSdf.parse(shortSdf.format(c.getTime()) + " 00:00:00"));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return c.getTime();
    }
 
    /**
     * 获得本周的最后一天，周日
     *
     * @return
     */
    public static Date getCurrentWeekDayEndTime() {
        Calendar c = Calendar.getInstance();
        try {
            int weekday = c.get(Calendar.DAY_OF_WEEK);
            c.add(Calendar.DATE, 8 - weekday);
            c.setTime(longSdf.parse(shortSdf.format(c.getTime()) + " 23:59:59"));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return c.getTime();
    }
 
    /**
     * 获得本天的开始时间
     *
     * @return
     */
    public static Date getCurrentDayStartTime() {
        Date now = new Date();
        try {
            now = shortSdf.parse(shortSdf.format(now));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 获得本天的结束时间
     *
     * @return
     */
    public static Date getCurrentDayEndTime() {
        Date now = new Date();
        try {
            now = longSdf.parse(shortSdf.format(now) + " 23:59:59");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 获得本小时的开始时间
     *
     * @return
     */
    public static Date getCurrentHourStartTime() {
        Date now = new Date();
        try {
            now = longHourSdf.parse(longHourSdf.format(now));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 获得本小时的结束时间
     *
     * @return
     */
    public static Date getCurrentHourEndTime() {
        Date now = new Date();
        try {
            now = longSdf.parse(longHourSdf.format(now) + ":59:59");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 获得本月的开始时间
     *
     * @return
     */
    public static Date getCurrentMonthStartTime() {
        Calendar c = Calendar.getInstance();
        Date now = null;
        try {
            c.set(Calendar.DATE, 1);
            now = shortSdf.parse(shortSdf.format(c.getTime()));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 本月的结束时间
     *
     * @return
     */
    public static Date getCurrentMonthEndTime() {
        Calendar c = Calendar.getInstance();
        Date now = null;
        try {
            c.set(Calendar.DATE, 1);
            c.add(Calendar.MONTH, 1);
            c.add(Calendar.DATE, -1);
            now = longSdf.parse(shortSdf.format(c.getTime()) + " 23:59:59");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 当前年的开始时间
     *
     * @return
     */
    public static Date getCurrentYearStartTime() {
        Calendar c = Calendar.getInstance();
        Date now = null;
        try {
            c.set(Calendar.MONTH, 0);
            c.set(Calendar.DATE, 1);
            now = shortSdf.parse(shortSdf.format(c.getTime()));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 当前年的结束时间
     *
     * @return
     */
    public static Date getCurrentYearEndTime() {
        Calendar c = Calendar.getInstance();
        Date now = null;
        try {
            c.set(Calendar.MONTH, 11);
            c.set(Calendar.DATE, 31);
            now = longSdf.parse(shortSdf.format(c.getTime()) + " 23:59:59");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 当前季度的开始时间
     *
     * @return
     */
    public static Date getCurrentQuarterStartTime() {
        Calendar c = Calendar.getInstance();
        int currentMonth = c.get(Calendar.MONTH) + 1;
        Date now = null;
        try {
            if (currentMonth >= 1 && currentMonth <= 3) {

                c.set(Calendar.MONTH, 0);
            }
            else if (currentMonth >= 4 && currentMonth <= 6) {

                c.set(Calendar.MONTH, 3);
            }
            else if (currentMonth >= 7 && currentMonth <= 9) {

                c.set(Calendar.MONTH, 6);
            }
            else if (currentMonth >= 10 && currentMonth <= 12) {

                c.set(Calendar.MONTH, 9);
            }
            c.set(Calendar.DATE, 1);
            now = longSdf.parse(shortSdf.format(c.getTime()) + " 00:00:00");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 当前季度的结束时间
     *
     * @return
     */
    public static Date getCurrentQuarterEndTime() {
        Calendar c = Calendar.getInstance();
        int currentMonth = c.get(Calendar.MONTH) + 1;
        Date now = null;
        try {
            if (currentMonth >= 1 && currentMonth <= 3) {
                c.set(Calendar.MONTH, 2);
                c.set(Calendar.DATE, 31);
            } else if (currentMonth >= 4 && currentMonth <= 6) {
                c.set(Calendar.MONTH, 5);
                c.set(Calendar.DATE, 30);
            } else if (currentMonth >= 7 && currentMonth <= 9) {
                c.set(Calendar.MONTH, 8);
                c.set(Calendar.DATE, 30);
            } else if (currentMonth >= 10 && currentMonth <= 12) {
                c.set(Calendar.MONTH, 11);
                c.set(Calendar.DATE, 31);
            }
            now = longSdf.parse(shortSdf.format(c.getTime()) + " 23:59:59");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
 
    /**
     * 获取前/后半年的开始时间
     *
     * @return
     */
    public static Date getHalfYearStartTime() {
        Calendar c = Calendar.getInstance();
        int currentMonth = c.get(Calendar.MONTH) + 1;
        Date now = null;
        try {
            if (currentMonth >= 1 && currentMonth <= 6) {
                c.set(Calendar.MONTH, 0);
            } else if (currentMonth >= 7 && currentMonth <= 12) {
                c.set(Calendar.MONTH, 6);
            }
            c.set(Calendar.DATE, 1);
            now = longSdf.parse(shortSdf.format(c.getTime()) + " 00:00:00");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
 
    }
 
    /**
     * 获取前/后半年的结束时间
     *
     * @return
     */
    public static Date getHalfYearEndTime() {
        Calendar c = Calendar.getInstance();
        int currentMonth = c.get(Calendar.MONTH) + 1;
        Date now = null;
        try {
            if (currentMonth >= 1 && currentMonth <= 6) {
                c.set(Calendar.MONTH, 5);
                c.set(Calendar.DATE, 30);
            } else if (currentMonth >= 7 && currentMonth <= 12) {
                c.set(Calendar.MONTH, 11);
                c.set(Calendar.DATE, 31);
            }
            now = longSdf.parse(shortSdf.format(c.getTime()) + " 23:59:59");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return now;
    }
}