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Java时间类记录

一、前言

• 环境说明：

JDK：1.8

官方API文档：

二、记录

• java.util.Date

参考：

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Date date = new Date();System.out.println(sdf.format(date));

• java.util.Calendar

参考：

Calendar calendar = Calendar.getInstance();int year = calendar.get(Calendar.YEAR);int month = calendar.get(Calendar.MONTH) + 1;int day = calendar.get(Calendar.DATE);// int hour = calendar.get(Calendar.HOUR); // 12小时制int hour = calendar.get(Calendar.HOUR_OF_DAY); // 24小时制int minute = calendar.get(Calendar.MINUTE);int second = calendar.get(Calendar.SECOND);System.out.println(year +"-"+ month +"-"+ day +" "+ hour +":"+ minute +":"+ second);// orSimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");System.out.println(sdf.format(calendar.getTime()));

• java.time.LocalDate 、java.time.LocalTime 、java.time.LocalDateTime

JDK：1.8+

参考：

DateTimeFormatter dateDTF = DateTimeFormatter.ofPattern("yyyy-MM-dd");LocalDate localDate = LocalDate.now();DateTimeFormatter timeDTF = DateTimeFormatter.ofPattern("HH:mm:ss");LocalTime localTime = LocalTime.now();System.out.println(localDate.format(dateDTF) +" "+ localTime.format(timeDTF));// orDateTimeFormatter datetimeDTF = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");LocalDateTime localDateTime = LocalDateTime.now();System.out.println(localDateTime.format(datetimeDTF));

• System.currentTimeMillis()

参考：

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Date date = new Date(System.currentTimeMillis());System.out.println(sdf.format(date));

• java.sql.Timestamp

参考：

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Date date = new Date();Timestamp timestamp = new Timestamp(date.getTime());System.out.println(sdf.format(timestamp));// ortimestamp = new Timestamp(System.currentTimeMillis());date = new Date(timestamp.getTime());System.out.println(sdf.format(date));

• java.sql.Date

参考：

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");Date date = new Date();java.sql.Date sqlDate = new java.sql.Date(date.getTime());System.out.println(sdf.format(sqlDate));// orsqlDate = new java.sql.Date(System.currentTimeMillis());date = new Date(sqlDate.getTime());System.out.println(sdf.format(date));

三、其它

1.获取未来或过去24小时的时间

SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");Calendar calendar = Calendar.getInstance();calendar.setTime(new Date()); // 设置当前时间for(int i=0; i< 24; i++){
       String time = sdf.format(calendar.getTime());    System.out.println(time);    // 如果 -1 则为是过去24小时的时间    calendar.set(Calendar.HOUR_OF_DAY, calendar.get(Calendar.HOUR_OF_DAY) + 1);}

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