zoukankan html css js c++ java

Java日期时间API系列26-----Jdk8中java.time包中的新的日期时间API类，YearMonth类的源码，转换和应用。

Java8中为年月新增了类YearMonth，可以用来表示卡片过期时间等问题。

1.YearMonth

默认格式为：2007-12

1.1 部分源码

*
 * @implSpec
 * This class is immutable and thread-safe.
 *
 * @since 1.8
 */
public final class YearMonth
        implements Temporal, TemporalAdjuster, Comparable<YearMonth>, Serializable {

    /**
     * Serialization version.
     */
    private static final long serialVersionUID = 4183400860270640070L;
    /**
     * Parser.
     */
    private static final DateTimeFormatter PARSER = new DateTimeFormatterBuilder()
        .appendValue(YEAR, 4, 10, SignStyle.EXCEEDS_PAD)
        .appendLiteral('-')
        .appendValue(MONTH_OF_YEAR, 2)
        .toFormatter();

    /**
     * The year.
     */
    private final int year;
    /**
     * The month-of-year, not null.
     */
    private final int month;

通过源码可以看出使用final修饰YearMonth，YearMonth是线程安全类，同时实现了Temporal, TemporalAdjuster, Comparable<YearMonth>, Serializable接口，有属性读取，设置和加减等功能。

1.2 创建和基本使用

        YearMonth yearMonth = YearMonth.now();
        YearMonth yearMonth2 = YearMonth.of(2020, 4);
        
        System.out.println(yearMonth);
        System.out.println(yearMonth2);
        YearMonth yearMonth3 = YearMonth.parse("2020-05");
        System.out.println(yearMonth3);
        
        YearMonth yearMonth4 = yearMonth3.plusMonths(1);
        System.out.println(yearMonth4);

输出：

2.应用

2.1 转换

如Date转YearMonth，YearMonth转Date等

    /**
     * Date转YearMonth
     * @param date
     * @return
     */
    public static YearMonth toYearMonth(Date date){
        LocalDate localDate = toLocalDate(date);
        return YearMonth.of(localDate.getYear(), localDate.getMonthValue());
    }
    
    /**
     * LocalDateTime转YearMonth
     * @param localDateTime
     * @return
     */
    public static YearMonth toYearMonth(LocalDateTime localDateTime){
        LocalDate localDate = toLocalDate(localDateTime);
        return YearMonth.of(localDate.getYear(), localDate.getMonthValue());
    }
    
    /**
     * LocalDate转YearMonth
     * @param localDate
     * @return
     */
    public static YearMonth toYearMonth(LocalDate localDate){
        Objects.requireNonNull(localDate, "localDate");
        return YearMonth.of(localDate.getYear(), localDate.getMonthValue());
    }
    
    /**
     * Instant转YearMonth
     * @param instant
     * @return
     */
    public static YearMonth toYearMonth(Instant instant){
        LocalDate localDate = toLocalDate(instant);
        return YearMonth.of(localDate.getYear(), localDate.getMonthValue());
    }
    
    /**
     * ZonedDateTime转YearMonth
     * @param zonedDateTime
     * @return
     */
    public static YearMonth toYearMonth(ZonedDateTime zonedDateTime){
        LocalDate localDate = toLocalDate(zonedDateTime);
        return YearMonth.of(localDate.getYear(), localDate.getMonthValue());
    }

    /**
     * YearMonth转Date
     * 注意dayOfMonth范围：1到31之间，最大值根据月份确定特殊情况，如2月闰年29，非闰年28
     * 如果要转换为当月最后一天，可以使用下面方法：toDateEndOfMonth(YearMonth)
     * @param yearMonth
     * @param dayOfMonth
     * @return
     */
    public static Date toDate(YearMonth yearMonth, int dayOfMonth) {
        Objects.requireNonNull(yearMonth, "yearMonth");
        return toDate(yearMonth.atDay(dayOfMonth));
    }
    
    /**
     * YearMonth转Date，转换为当月第一天
     * @param yearMonth
     * @return
     */
    public static Date toDateStartOfMonth(YearMonth yearMonth) {
        return toDate(yearMonth, 1);
    }
    
    /**
     * YearMonth转Date，转换为当月最后一天
     * @param yearMonth
     * @return
     */
    public static Date toDateEndOfMonth(YearMonth yearMonth) {
        Objects.requireNonNull(yearMonth, "yearMonth");
        return toDate(yearMonth.atEndOfMonth());
    }

    /**
     * YearMonth转LocalDate
     * 注意dayOfMonth范围：1到31之间，最大值根据月份确定特殊情况，如2月闰年29，非闰年28
     * 如果要转换为当月最后一天，可以使用下面方法：toLocalDateEndOfMonth(YearMonth)
     * @param yearMonth
     * @param dayOfMonth
     * @return
     */
    public static LocalDate toLocalDate(YearMonth yearMonth, int dayOfMonth) {
        Objects.requireNonNull(yearMonth, "yearMonth");
        return yearMonth.atDay(dayOfMonth);
    }
    
    /**
     * YearMonth转LocalDate，转换为当月第一天
     * @param yearMonth
     * @return
     */
    public static LocalDate toLocalDateStartOfMonth(YearMonth yearMonth) {
        return toLocalDate(yearMonth, 1);
    }
    
    /**
     * YearMonth转LocalDate，转换为当月最后一天
     * @param yearMonth
     * @return
     */
    public static LocalDate toLocalDateEndOfMonth(YearMonth yearMonth) {
        Objects.requireNonNull(yearMonth, "yearMonth");
        return yearMonth.atEndOfMonth();
    }

测试代码：

    @Test
    public void yearMonthConverterTest(){
        System.out.println("===================yearMonthConverterTest=====================");
        Date date = new Date();
        System.out.println(date);
        YearMonth yearMonth = DateTimeConverterUtil.toYearMonth(date);
        System.out.println(yearMonth);
        
        Date date1 = DateTimeConverterUtil.toDate(yearMonth, 15);
        //转换为当月第一天
        Date date2 = DateTimeConverterUtil.toDateStartOfMonth(yearMonth);
        //转换为当月最后一天
        Date date3 = DateTimeConverterUtil.toDateEndOfMonth(yearMonth);
        System.out.println(date1);
        System.out.println(date2);
        System.out.println(date3);
        
        LocalDate LocalDate1 = DateTimeConverterUtil.toLocalDate(yearMonth, 15);
        //转换为当月第一天
        LocalDate LocalDate2 = DateTimeConverterUtil.toLocalDateStartOfMonth(yearMonth);
        //转换为当月最后一天
        LocalDate LocalDate3 = DateTimeConverterUtil.toLocalDateEndOfMonth(yearMonth);
        System.out.println(LocalDate1);
        System.out.println(LocalDate2);
        System.out.println(LocalDate3);
    }

输出:

===================yearMonthConverterTest=====================
Fri Mar 20 23:41:41 CST 2020
2020-03
Sun Mar 15 00:00:00 CST 2020
Sun Mar 01 00:00:00 CST 2020
Tue Mar 31 00:00:00 CST 2020
2020-03-15
2020-03-01
2020-03-31

2.2 计算

获取起始日期中间的日期列表，获取指定月份的日期列表，判断是否过期等等

    /**
     * 获取指定区间的时间列表，包含起始
     * @param startInclusive
     * @param endInclusive
     * @return
     */
    public static List<LocalDateTime> getLocalDateTimeList(LocalDateTime startInclusive, LocalDateTime endInclusive){
        Objects.requireNonNull(startInclusive, "startInclusive");
        Objects.requireNonNull(endInclusive, "endInclusive");
        if(startInclusive.isAfter(endInclusive)){
            throw new DateTimeException("startInclusive must before or equal endInclusive!");
        }
        List<LocalDateTime> localDateTimeList = new ArrayList<LocalDateTime>();
        long days = betweenTotalDays(startInclusive, endInclusive)+1;
        for(long i=0; i<days; i++){
            localDateTimeList.add(startInclusive.plusDays(i));
        }
        return localDateTimeList;
    }
    
    /**
     * 获取指定区间的时间列表，包含起始
     * @param startInclusive
     * @param endInclusive
     * @return
     */
    public static List<LocalDate> getLocalDateList(LocalDate startInclusive, LocalDate endInclusive){
        return getLocalDateTimeList(DateTimeConverterUtil.toLocalDateTime(startInclusive),
                DateTimeConverterUtil.toLocalDateTime(endInclusive)).stream()
                        .map(localDateTime -> localDateTime.toLocalDate()).collect(Collectors.toList());
    }
    
    /**
     * 获取指定区间的时间列表，包含起始
     * @param startInclusive
     * @param endInclusive
     * @return
     */
    public static List<Date> getDateList(Date startInclusive, Date endInclusive){
        return getLocalDateTimeList(DateTimeConverterUtil.toLocalDateTime(startInclusive),
                DateTimeConverterUtil.toLocalDateTime(endInclusive)).stream()
                        .map(localDateTime -> DateTimeConverterUtil.toDate(localDateTime)).collect(Collectors.toList());
    }
    
    /**
     *  获取指定年月的所有日期列表
     * @param YearMonth
     * @return
     */
    public static List<LocalDate> getLocalDateList(YearMonth yearMonth){
        Objects.requireNonNull(yearMonth, "yearMonth");
        List<LocalDate> localDateList = new ArrayList<LocalDate>();
        long days = yearMonth.lengthOfMonth();
        LocalDate localDate = DateTimeConverterUtil.toLocalDateStartOfMonth(yearMonth);
        for(long i=0; i<days; i++){
            localDateList.add(plusDays(localDate, i));
        }
        return localDateList;
    }
    
    /**
     *  获取指定年月的所有日期列表
     * @param yearMonthStr yyyy-MM
     * @return
     */
    public static List<LocalDate> getLocalDateList(String yearMonthStr){
        Objects.requireNonNull(yearMonthStr, "yearMonthStr");
        YearMonth yearMonth = YearMonth.parse(yearMonthStr);
        return getLocalDateList(yearMonth);
    }
    
    /**
     *  获取指定年月的所有日期列表
     * @param yearMonth
     * @return
     */
    public static List<LocalDateTime> getLocalDateTimeList(YearMonth yearMonth){
        return getLocalDateList(yearMonth).stream()
                .map(localDate -> DateTimeConverterUtil.toLocalDateTime(localDate)).collect(Collectors.toList());
    }    
    
    /**
     *  获取指定年月的所有日期列表
     * @param yearMonthStr yyyy-MM
     * @return
     */
    public static List<LocalDateTime> getLocalDateTimeList(String yearMonthStr){
        return getLocalDateList(yearMonthStr).stream()
                .map(localDate -> DateTimeConverterUtil.toLocalDateTime(localDate)).collect(Collectors.toList());
    }
    
    /**
     * 获取指定年月的所有日期列表
     * @param yearMonthStr yyyy-MM
     * @return
     */
    public static List<Date> getDateList(String yearMonthStr){
        return getLocalDateList(yearMonthStr).stream().map(localDate -> DateTimeConverterUtil.toDate(localDate))
                .collect(Collectors.toList());
    }
    
    /**
     * 判断是否过期，（输入年月小于当前年月）
     * @param yearMonth
     * @return
     */
    public static boolean isExpiry(YearMonth yearMonth){
        Objects.requireNonNull(yearMonth, "yearMonth");
        if(yearMonth.isBefore(YearMonth.now())){
            return true;
        }
        return false;
    }
    
    /**
     * 判断是否过期，（输入年月小于当前年月）
     * @param yearMonthStr yyyy-MM
     * @return
     */
    public static boolean isExpiry(String yearMonthStr){
        Objects.requireNonNull(yearMonthStr, "yearMonthStr");
        YearMonth yearMonth = YearMonth.parse(yearMonthStr);
        return isExpiry(yearMonth);
    }

测试代码：

    /**
     * yearMonth测试
     */
    @Test
    public void yearMonthTest(){
        //是否过期
        System.out.println(DateTimeCalculatorUtil.isExpiry("2020-03"));
        
        //获取指定年月的所有日期列表
        List<Date> dateList = DateTimeCalculatorUtil.getDateList("2020-03");
        dateList.stream().forEach(date->{
            System.out.println(DateTimeFormatterUtil.formatToDateStr(date));
        });
        
        System.out.println("========================");

        //获取指定区间的时间列表，包含起始
        List<Date> dateList2 = DateTimeCalculatorUtil.getDateList(dateList.get(0), dateList.get(dateList.size()-1));
        dateList2.stream().forEach(date->{
            System.out.println(DateTimeFormatterUtil.formatToDateStr(date));
        });
        
    }

输出：

false
2020-03-01
2020-03-02
2020-03-03
2020-03-04
2020-03-05
2020-03-06
2020-03-07
2020-03-08
2020-03-09
2020-03-10
2020-03-11
2020-03-12
2020-03-13
2020-03-14
2020-03-15
2020-03-16
2020-03-17
2020-03-18
2020-03-19
2020-03-20
2020-03-21
2020-03-22
2020-03-23
2020-03-24
2020-03-25
2020-03-26
2020-03-27
2020-03-28
2020-03-29
2020-03-30
2020-03-31
========================
2020-03-01
2020-03-02
2020-03-03
2020-03-04
2020-03-05
2020-03-06
2020-03-07
2020-03-08
2020-03-09
2020-03-10
2020-03-11
2020-03-12
2020-03-13
2020-03-14
2020-03-15
2020-03-16
2020-03-17
2020-03-18
2020-03-19
2020-03-20
2020-03-21
2020-03-22
2020-03-23
2020-03-24
2020-03-25
2020-03-26
2020-03-27
2020-03-28
2020-03-29
2020-03-30
2020-03-31

源代码地址：https://github.com/xkzhangsan/xk-time

查看全文

相关阅读:
POJ 1015 Jury Compromise【DP】
POJ 1661 Help Jimmy【DP】
HDU 1074 Doing Homework【状态压缩DP】
HDU 1024 Max Sum Plus Plus【DP，最大m子段和】
占坑补题。。最近占的坑有点多。。。
Codeforces 659F Polycarp and Hay【BFS】
Codeforces 659E New Reform【DFS】
Codeforces 659D Bicycle Race【计算几何】
廖大python实战项目第四天
 廖大python实战项目第三天

原文地址：https://www.cnblogs.com/xkzhangsanx/p/12535828.html