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3.5. Date 日期时间
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3.5. Date 日期时间

java.util.Date, java.sql.Date, java.sql.Time, java.sql.Timestamp 区别 

		
package cn.netkiller.java.date;

/**
 * Hello world!
 *
 */
public class App {
	public static void main(String[] args) {
		System.out.println("Hello World!");

		// Get standard date and time
		java.util.Date utilDate = new java.util.Date();
		long javaTime = utilDate.getTime();
		System.out.println("The Java Date is:" + utilDate.toString());

		// Get and display SQL DATE
		java.sql.Date sqlDate = new java.sql.Date(javaTime);
		System.out.println("The SQL DATE is: " + sqlDate.toString());

		// Get and display SQL TIME
		java.sql.Time sqlTime = new java.sql.Time(javaTime);
		System.out.println("The SQL TIME is: " + sqlTime.toString());
		
		// Get and display SQL TIMESTAMP
		java.sql.Timestamp sqlTimestamp = new java.sql.Timestamp(javaTime);
		System.out.println("The SQL TIMESTAMP is: " + sqlTimestamp.toString());
	}
}

		
		
		
The Java Date is:Thu Aug 24 16:51:57 CST 2017
The SQL DATE is: 2017-08-24
The SQL TIME is: 16:51:57
The SQL TIMESTAMP is: 2017-08-24 16:51:57.234

3.5.1. DateTimeFormatter 格式化日期和时间

			
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
 
public class Main {
    public static void main(String[] args) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        LocalDateTime dateTime = LocalDateTime.now();
        String formattedDateTime = dateTime.format(formatter);
        System.out.println(formattedDateTime);
    }
}
			
			
			
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("B");
        System.out.println(dtf.format(LocalTime.of(8, 0)));
        System.out.println(dtf.format(LocalTime.of(13, 0)));
        System.out.println(dtf.format(LocalTime.of(20, 0)));
        System.out.println(dtf.format(LocalTime.of(23, 0)));
        System.out.println(dtf.format(LocalTime.of(0, 0)));			
			
			

			
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3.5.2. SimpleDateFormat 格式化日期和时间

字符串转日期

			
        try {

            DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
            String str = "2018-12-11";
            Date date = df.parse(str);
            System.out.println(date);

        } catch (Exception e) {
            e.printStackTrace();
        }			
			
			
			

public static void main(String[] args) {

	DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
	//get current date time with Date()
	Date date = new Date();
	System.out.println(dateFormat.format(date));
	
	//get current date time with Calendar()
	Calendar cal = Calendar.getInstance();
	System.out.println(dateFormat.format(cal.getTime()));

}

不规范的 RFC3339 日期

			
		String dt = "2021-08-26T09:17:23.859291804+08:00";
		String rfc3339 = dt.replaceAll("\\.([0-9]+)", "");
		System.out.println(dt);
		System.out.println(rfc3339);
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX");
		simpleDateFormat.setTimeZone(TimeZone.getTimeZone("GMT+8"));
		System.out.println(simpleDateFormat.parse(rfc3339).toLocaleString());

3.5.3. Timestamp

			
Timestamp timestamp = new Timestamp(System.currentTimeMillis());

Date date = new Date();
Timestamp timestamp = new Timestamp(date.getTime());

3.5.4. TimeZone

			
package cn.netkiller.example;

import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;

public class TimeZoneTest {
	
	public TimeZoneTest() {
		// TODO Auto-generated constructor stub
	}
	
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		
		TimeZone timeZone = TimeZone.getTimeZone("Asia/Harbin");
		
		Date date = new Date();
		Timestamp timestamp = new Timestamp(date.getTime());
		
		System.out.println(timestamp);
		
		timestamp.setHours(timestamp.getHours()+8);
		System.out.println(timestamp);
		
		simpleDateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
		System.out.println(simpleDateFormat.format(date));
		
		simpleDateFormat.setTimeZone(TimeZone.getTimeZone("Asia/Harbin"));
		System.out.println(simpleDateFormat.format(date));
		
		Calendar calendar = new GregorianCalendar();
		calendar.setTime(date);
		calendar.setTimeZone(timeZone);
		System.out.println(simpleDateFormat.format(calendar.getTime()));
	}

}

3.5.5. String to Date

			
package cn.netkiller.example;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class StringToDate {

	public StringToDate() {
		// TODO Auto-generated constructor stub
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String dateString = "2008-8-8 8:8:8";

		try {

			Date date = formatter.parse(dateString);
			System.out.println(date);
			System.out.println(formatter.format(date));

		} catch (ParseException e) {
			e.printStackTrace();
		}
	}

}

3.5.6. 比较两个日期与时间

			
package cn.netkiller.example;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateCompare {

	public DateCompare() {
		// TODO Auto-generated constructor stub
	}

	public void fun1() throws InterruptedException {
		Date d1 = new Date();
		Thread.sleep(5000);
		Date d2 = new Date();
		if (d1.before(d2)) {
			System.out.println(String.format("%s < %s", d1.toString(), d2.toString()));
		} else {
			System.out.println(String.format("%s > %s", d1.toString(), d2.toString()));
		}
		if (d2.after(d1)) {
			System.out.println(String.format("%s > %s", d2.toString(), d1.toString()));
		}

		System.out.println(String.format("%s : %s => %d", d2.toString(), d1.toString(), d1.compareTo(d2)));
		System.out.println(String.format("%s : %s => %d", d1.toString(), d2.toString(), d2.compareTo(d1)));
	}

	public void fun2() throws InterruptedException {

		DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

		Date date1 = new Date();
		Date date2 = new Date();
		String s1 = dateFormat.format(date1);
		String s2 = dateFormat.format(date2);
		System.out.println(String.format("%s : %s => %d", s1, s2, s1.compareTo(s2)));

		date1 = new Date();
		Thread.sleep(5000);
		date2 = new Date();
		s1 = dateFormat.format(date1);
		s2 = dateFormat.format(date2);
		System.out.println(String.format("%s : %s => %d", s1, s2, s1.compareTo(s2)));
		System.out.println(String.format("%s : %s => %d", s2, s1, s2.compareTo(s1)));
		System.out.println();
	}

	public void fun3() throws InterruptedException, ParseException {
		DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm");
		//Date time = formatter.parse("2016-09-27 16:29");
		Date time = formatter.parse("2016-08-09 09:15");
		Date startDate = formatter.parse("2016-08-09 09:15");
		Date endDate = formatter.parse("2016-09-27 16:30");
		
		if (time.before(startDate) || time.after(endDate)) {
			System.out.println("Skip");
		}
	}

	public static void main(String[] args) throws InterruptedException {
		// TODO Auto-generated method stub
		DateCompare dateCompare = new DateCompare();
		dateCompare.fun1();
		System.out.println();
		dateCompare.fun2();
		System.out.println();
		dateCompare.fun3();
	}

}

3.5.7. Calendar

				
		Calendar cal = Calendar.getInstance();
		int year = cal.get(Calendar.YEAR);
		int month = cal.get(Calendar.MONTH )+1;
		
		System.out.println(year + "年 " + month + "月");

3.5.8. getToday

			
	public Date getToday(String time) {
		final Calendar cal = Calendar.getInstance();
		DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd " + time);
		DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date date = null;
		try {
			date = fmt.parse(dateFormat.format(cal.getTime()));
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return date;
	}

	private Date addOneDay(Date date, int day) {
		Calendar cal = Calendar.getInstance();
		cal.setTime(date);
		cal.add(Calendar.DATE, day);
		return cal.getTime();
	}

3.5.9. Yesterday

					
package cn.netkiller.date;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Yesterday {

	public Yesterday() {
		// TODO Auto-generated constructor stub
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Yesterday yesterday = new Yesterday();
		System.out.println(yesterday.yesterday());
		System.out.println(yesterday.getYesterday("00:00:00"));
		System.out.println(yesterday.getYesterday("23:59:59"));
	}
	private Date yesterday() {
	    final Calendar cal = Calendar.getInstance();
	    cal.add(Calendar.DATE, -1);
	    return cal.getTime();
	}

	private Date getYesterday(String time) {
	        DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd "+time);
	        
	        DateFormat fmt =new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	        Date date = null;
	        try {
	            date = fmt.parse(dateFormat.format(yesterday()));
	        } catch (ParseException e) {
	            e.printStackTrace();
	        }
	        return date;
	}
}

3.5.10. ISO 8601

			
ISO 8601扩展格式 YYYY-MM-DDTHH:mm:ss.sssZ

3.5.11. LocalDateTime

			
	LocalDateTime localDateTime = LocalDateTime.of(2016, 1, 1, 13, 55);
	ZonedDateTime zonedDateTime = localDateTime.atZone(ZoneId.of("Asia/Shanghai"));
	Date date = Date.from(zonedDateTime.toInstant());	
		
	Instant instant = Instant.ofEpochMilli(date.getTime());
    LocalDateTime ldt = LocalDateTime.ofInstant(instant, ZoneOffset.UTC);
    Instant instant = ldt.toInstant(ZoneOffset.UTC);
    Date date = Date.from(instant);
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