Java –如何获取当前日期时间

痛定思痛。 2023-03-14 08:14 53阅读 0赞

在本文中，我将向您展示如何从经典的[Date][]和[Calendar][] API以及新的Java 8日期和时间API – [LocalDateTime][]和[LocalDate][]获取当前日期时间。

## 1.代码 ##

对于`java.util.Date`，只需创建一个新的Date（）

DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
    Date date = new Date();
    System.out.println(dateFormat.format(date)); //2020/05/16 12:08:43

对于`java.util.Calendar`，使用Calendar.getInstance（）

DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
    Calendar cal = Calendar.getInstance();
    System.out.println(dateFormat.format(cal)); //2020/05/16 12:08:43

对于`java.time.LocalDateTime`，使用LocalDateTime.now（）

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
    LocalDateTime now = LocalDateTime.now();
    System.out.println(dtf.format(now)); //2020/05/16 12:08:43

对于`java.time.LocalDate`，使用LocalDate.now（）

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy/MM/dd");
    LocalDate localDate = LocalDate.now();
    System.out.println(dtf.format(localDate)); //2020/05/16

## 2.完整例子 ##

查看完整的Java示例，向您展示如何获取当前日期，时间并以预定义的格式显示。

GetCurrentDateTime.java

package com.lintao;
    
    import java.text.DateFormat;
    import java.text.SimpleDateFormat;
    import java.time.LocalDateTime;
    import java.time.format.DateTimeFormatter;
    import java.util.Calendar;
    import java.util.Date;
    
    public class GetCurrentDateTime { 
    
        private static final DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
        private static final DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
    
        public static void main(String[] args) { 
    
            Date date = new Date();
            System.out.println(sdf.format(date));
    
            Calendar cal = Calendar.getInstance();
            System.out.println(sdf.format(cal.getTime()));
    
            LocalDateTime now = LocalDateTime.now();
            System.out.println(dtf.format(now));
    
            LocalDate localDate = LocalDate.now();
            System.out.println(DateTimeFormatter.ofPattern("yyy/MM/dd").format(localDate));
    
        }
    
    }

输出

2020/05/16 12:08:43
    2020/05/16 12:08:43
    2020/05/16 12:08:43
    2020/05/16

## 参考文献 ##

1.  [Date JavaDoc][Date]
2.  [Calendar JavaDoc][Calendar]
3.  [SimpleDateFormat JavaDoc][]
4.  [LocalDateTime JavaDoc][LocalDateTime]
5.  [LocalDate JavaDoc][LocalDate]
6.  [DateTimeFormatter JavaDoc][]

[Date]: http://docs.oracle.com/javase/8/docs/api/java/util/Date.html
[Calendar]: http://docs.oracle.com/javase/8/docs/api/java/util/Calendar.html
[LocalDateTime]: http://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html
[LocalDate]: http://docs.oracle.com/javase/8/docs/api/java/time/LocalDate.html
[SimpleDateFormat JavaDoc]: http://docs.oracle.com/javase/8/docs/api/java/text/SimpleDateFormat.html
[DateTimeFormatter JavaDoc]: https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html