java日期互转：LocalDateTime、String、TimeStamp、Long、Instant、Date

亦凉 2024-04-08 11:45 15阅读 0赞

### java日期互转：LocalDateTime、String、TimeStamp、Long、Instant、Date ###

由于java版本的迭代，一个使用java开发的项目中可能出现多种日期对象，例如LocalDateTime、LocalDate、Date，各种日期格式或者对象之间的转换总结：

1、 LocalDateTime转为String、TimeStamp、Long、Instant、 Date

System.out.println("----------------LocalDateTime----------------");
    //LocalDateTime -> String
    String localDateTimeToString = LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
    System.out.println("LocalDateTime -> String:  " + localDateTimeToString);
    //LocalDateTime -> TimeStamp
    Timestamp localDateTimeToTimeStamp = Timestamp.valueOf(LocalDateTime.now());
    System.out.println("LocalDateTime -> TimeStamp:  " + localDateTimeToTimeStamp);
    //LocalDateTime -> Long
    Long localDateTimeToLong = Timestamp.valueOf(LocalDateTime.now()).getTime();
    System.out.println("LocalDateTime -> Long:  " + localDateTimeToLong);
    //LocalDateTime -> Instant
    Instant localDateTimeToInstant = LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant();
    System.out.println("LocalDateTime -> Instant:  " + localDateTimeToInstant);
    //LocalDateTime -> Date
    Date LocalDateTimeToDate = Date.from(LocalDateTime.now().atZone(ZoneId.systemDefault()).toInstant());
    System.out.println("LocalDateTime -> Date:  " + LocalDateTimeToDate);

2、String转为LocalDateTime、 Date

System.out.println("----------------String----------------");
    //String -> LocalDateTime
    LocalDateTime stringToLocalDateTime = LocalDateTime.parse("2022-08-24 15:30:11", DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
    System.out.println("String -> LocalDateTime:  " + stringToLocalDateTime);
    //String -> Date
    try {
        
        Date stringToDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").parse("2022-08-24 15:30:11");
        System.out.println("String -> Date:  " + stringToDate);
    } catch (ParseException ex) {
        
     
    }

3、Timestamp转为LocalDateTime、 Date

System.out.println("---------------Timestamp-----------------");
    //Timestamp -> LocalDateTime
    LocalDateTime timeStampToLocalDateTime =
            LocalDateTime.ofInstant(new Timestamp(1520754566856L).toInstant(), ZoneId.systemDefault());
    System.out.println("Timestamp -> LocalDateTime:  " + timeStampToLocalDateTime);
    //Timestamp -> Date
    Date timestampToDate = Date.from(new Timestamp(1520754566856L).toInstant());
    System.out.println("Timestamp -> Date:  " + timestampToDate);

4、Long转为LocalDateTime、 Date

System.out.println("---------------Long-----------------");
    //Long -> LocalDateTime
    LocalDateTime longToLocalDateTime =
            LocalDateTime.ofInstant(Instant.ofEpochMilli(1520754566856L), ZoneId.systemDefault());
    System.out.println("Long -> LocalDateTime:  " + longToLocalDateTime);
    //Long -> Date
    Date longToDate = new Date(1520754566856L);
    System.out.println("Long -> Date: " + longToDate);

5、Instant转为LocalDateTime、 Date

System.out.println("----------------Instant----------------");
    //Instant -> LocalDateTime
    LocalDateTime instantToLocalDateTime = LocalDateTime.ofInstant(Instant.now(), ZoneId.systemDefault());
    System.out.println("Instant -> LocalDateTime:  " + instantToLocalDateTime);
    //Instant -> Date
    Date instantToDate = Date.from(Instant.now());
    System.out.println("Instant -> Date:  " + instantToDate);

6、Date转为LocalDateTime、String、TimeStamp、Long、Instant

System.out.println("----------------Date----------------");
    //Date -> String
    String dateToString = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
    System.out.println("Date -> String:  " + dateToString);
    //Date -> LocalDateTime
    LocalDateTime dateToLocalDateTime = LocalDateTime.ofInstant(new Date().toInstant(), ZoneId.systemDefault());
    System.out.println("Date -> LocalDateTime:  " + dateToLocalDateTime);
    //Date -> Timestamp
    Timestamp dateToTimestamp = new Timestamp(new Date().getTime());
    System.out.println("Date -> Timestamp:  " + dateToTimestamp);
    //Date -> Long
    Long dateToLong = new Date().getTime();
    System.out.println("Date -> Long: " + dateToLong);
    //Date -> Instant
    Instant dateToInstant = new Date().toInstant();
    System.out.println("Date -> Instant:  " + dateToInstant);