DateTimeFormatter的使用格式转换及异常处理

ゝ一纸荒年。 2022-12-13 04:50 167阅读 0赞

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**目录**

DateTimeFormatter 格式化时间工具类 主要是与Date之间的转化

用DateTimeFormatter生成随机日期

用DateTimeFormatter格式化“yyyy-MM-dd”异常问题

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## [DateTimeFormatter 格式化时间工具类 主要是与Date之间的转化][DateTimeFormatter _ _Date] ##

[转载至][DateTimeFormatter _ _Date]

// 01. java.util.Date --> java.time.LocalDateTime
    public void DateToLocalDateTime() {
    java.util.Date date = new java.util.Date();
    Instant instant = date.toInstant();
    ZoneId zone = ZoneId.systemDefault();
    LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
    }
    
    // 02. java.util.Date --> java.time.LocalDate
    public void DateToLocalDate() {
    java.util.Date date = new java.util.Date();
    Instant instant = date.toInstant();
    ZoneId zone = ZoneId.systemDefault();
    LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
    LocalDate localDate = localDateTime.toLocalDate();
    }
    
    // 03. java.util.Date --> java.time.LocalTime
    public void DateToLocalTime() {
    java.util.Date date = new java.util.Date();
    Instant instant = date.toInstant();
    ZoneId zone = ZoneId.systemDefault();
    LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
    LocalTime localTime = localDateTime.toLocalTime();
    }
    
    
    // 04. java.time.LocalDateTime --> java.util.Date
    public void LocalDateTimeToDate() {
    LocalDateTime localDateTime = LocalDateTime.now();
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDateTime.atZone(zone).toInstant();
    java.util.Date date = Date.from(instant);
    }
    
    
    // 05. java.time.LocalDate --> java.util.Date
    public void LocalDateToDate() {
    LocalDate localDate = LocalDate.now();
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDate.atStartOfDay().atZone(zone).toInstant();
    java.util.Date date = Date.from(instant);
    }
    
    // 06. java.time.LocalTime --> java.util.Date
    public void LocalTimeToDate() {
    LocalTime localTime = LocalTime.now();
    LocalDate localDate = LocalDate.now();
    LocalDateTime localDateTime = LocalDateTime.of(localDate, localTime);
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = localDateTime.atZone(zone).toInstant();
    java.util.Date date = Date.from(instant);

## 用[DateTimeFormatter][DateTimeFormatter _ _Date]生成随机日期 ##

public class TestTYC {
    
        final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    
        @Test
        public void test() throws Exception {
            for (int i=0;i<30;i++){
    
                Date date = randomDate("1960-01-01 00:00:00","2002-01-31 00:00:00");
                Instant instant = date.toInstant();
                ZoneId zone = ZoneId.systemDefault();
                LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, zone);
                System.out.println(localDateTime.format(formatter));
            }
    
        }
    
        private  Date randomDate(String beginDate,String endDate){
    
            try {
    
                LocalDateTime start = LocalDateTime.parse(beginDate, formatter);
                LocalDateTime end = LocalDateTime.parse(endDate, formatter);
                if(start.isAfter(end)){
                    return null;
                }
                ZoneId zone = ZoneId.systemDefault();
                Instant startInstant = start.atZone(zone).toInstant();
                java.util.Date startTime= Date.from(startInstant);
    
                Instant endInstant = end.atZone(zone).toInstant();
                java.util.Date endTime = Date.from(endInstant);
    
                long date = random(startTime.getTime(),endTime.getTime());
    
                return new Date(date);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }
    
        private  long random(long begin,long end){
            long rtn = begin + (long)(Math.random() * (end - begin));
            if(rtn == begin || rtn == end){
                return random(begin,end);
            }
            return rtn;
        }

## 用[DateTimeFormatter][DateTimeFormatter _ _Date]格式化“yyyy-MM-dd”异常问题 ##

解决方式：

final DateTimeFormatter formatter = new DateTimeFormatterBuilder()
                .appendPattern("yyyy-MM-dd")
                .parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
                .parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
                .parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
                .parseDefaulting(ChronoField.MILLI_OF_SECOND, 0)
                .toFormatter();
    LocalDateTime localDateTime = LocalDateTime.parse("2018-12-11", formatter);

[DateTimeFormatter _ _Date]: https://www.cnblogs.com/duzjextjs/p/10461647.html