Java中时间API的基本使用教程

Date date1 = new Date();
Thread.sleep(1000);
long nowTime = System.currentTimeMillis();
Date date2 = new Date(nowTime);
//Date类和Java 8 API相互转换的接口
Instant instant = date2.toInstant();
Date date3 = Date.from(instant);

System.out.println("nowTime:"+nowTime);
System.out.println(date1);
System.out.println(date2);
System.out.println(date3);
System.out.println(date2.getTime());

//默认的方言
SimpleDateFormat sf = new SimpleDateFormat("G yyyy-MM-dd a z");
SimpleDateFormat sf1 = new SimpleDateFormat("G yyyy-MM-dd a z", Locale.US);
SimpleDateFormat sf2 = new SimpleDateFormat("G yyyy-MM-dd a z", Locale.KOREA);
String format1 = sf.format(date1);
String format2 = sf1.format(date1);
String format3 = sf2.format(date1);
System.out.println("format1:"+format1);
System.out.println("format2:"+format2);
System.out.println("format3:"+format3);
//解析Date
Date date = sf.parse(format1);

Calendar calendar = Calendar.getInstance();
int year = calendar.get(Calendar.YEAR);
// 获取月，这里需要需要月份的范围为0~11，因此获取月份的时候需要+1才是当前月份值
int month = calendar.get(Calendar.MONTH) + 1;
// 获取日
int day = calendar.get(Calendar.DAY_OF_MONTH);
// 获取时
int hour = calendar.get(Calendar.HOUR);
// 获取分
int minute = calendar.get(Calendar.MINUTE);
// 获取秒
int second = calendar.get(Calendar.SECOND);
System.out.println("现在是" + year + "年" + month + "月" + day + "日" + hour
    + "时" + minute + "分" + second + "秒");
//获取一个月后的今天
calendar.add(Calendar.MONTH,1);

//Current Date
LocalDate today = LocalDate.now();
System.out.println("Current Date="+today);

//Creating LocalDate by providing input arguments
LocalDate firstDay_2014 = LocalDate.of(2014, Month.JANUARY, 1);
System.out.println("Specific Date="+firstDay_2014);

//Try creating date by providing invalid inputs
//LocalDate feb29_2014 = LocalDate.of(2014, Month.FEBRUARY, 29);
//Exception in thread "main" java.time.DateTimeException:
//Invalid date 'February 29' as '2014' is not a leap year

//Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalDate todayKolkata = LocalDate.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Date in IST="+todayKolkata);

//Getting date from the base date i.e 01/01/1970
LocalDate dateFromBase = LocalDate.ofEpochDay(365);
System.out.println("365th day from base date= "+dateFromBase);

//2014年的第100天
LocalDate hundredDay2014 = LocalDate.ofYearDay(2014, 100);
System.out.println("100th day of 2014="+hundredDay2014);

//Current Time
LocalTime time = LocalTime.now();
System.out.println("Current Time="+time);

//Creating LocalTime by providing input arguments
LocalTime specificTime = LocalTime.of(12,20,25,40);
System.out.println("Specific Time of Day="+specificTime);

//Try creating time by providing invalid inputs
//LocalTime invalidTime = LocalTime.of(25,20);
//Exception in thread "main" java.time.DateTimeException:
//Invalid value for HourOfDay (valid values 0 - 23): 25

//Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalTime timeKolkata = LocalTime.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Time in IST="+timeKolkata);

//java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
//LocalTime todayIST = LocalTime.now(ZoneId.of("IST"));

//Getting date from the base date i.e 01/01/1970
LocalTime specificSecondTime = LocalTime.ofSecondOfDay(10000);
System.out.println("10000th second time= "+specificSecondTime);

//Current Date
LocalDateTime today = LocalDateTime.now();
System.out.println("Current DateTime="+today);

//Current Date using LocalDate and LocalTime
today = LocalDateTime.of(LocalDate.now(), LocalTime.now());
System.out.println("Current DateTime="+today);

//Creating LocalDateTime by providing input arguments
LocalDateTime specificDate = LocalDateTime.of(2014, Month.JANUARY, 1, 10, 10, 30);
System.out.println("Specific Date="+specificDate);

//Try creating date by providing invalid inputs
//LocalDateTime feb29_2014 = LocalDateTime.of(2014, Month.FEBRUARY, 28, 25,1,1);
//Exception in thread "main" java.time.DateTimeException:
//Invalid value for HourOfDay (valid values 0 - 23): 25

//Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
LocalDateTime todayKolkata = LocalDateTime.now(ZoneId.of("Asia/Kolkata"));
System.out.println("Current Date in IST="+todayKolkata);

//java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
//LocalDateTime todayIST = LocalDateTime.now(ZoneId.of("IST"));

//Getting date from the base date i.e 01/01/1970
LocalDateTime dateFromBase = LocalDateTime.ofEpochSecond(10000, 0, ZoneOffset.UTC);
System.out.println("10000th second time from 01/01/1970= "+dateFromBase);

//Current timestamp
Instant timestamp = Instant.now();
System.out.println("Current Timestamp = "+timestamp);

//Instant from timestamp
Instant specificTime = Instant.ofEpochMilli(timestamp.toEpochMilli());
System.out.println("Specific Time = "+specificTime);

//Duration example
Duration thirtyDay = Duration.ofDays(30);
System.out.println(thirtyDay);

//DateTimeFormatter支持的模式和SimpleDateFormat支持的一致
today.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日"));
5.6 对旧时间API的支持
  Date date= new Date();Instant instant = date.toInstant();LocalDateTime pst = LocalDateTime.ofInstant(instant, 
  ZoneId.of(ZoneId.SHORT_IDS.get("PST")));Calendar calendar = Calendar.getInstance();Instant instant1 = calendar.toInstant();LocalDateTime pst1 = LocalDateTime.ofInstant(instant, 
  ZoneId.of(ZoneId.SHORT_IDS.get("PST")));