Java中 Date Calendar GregorianCalendar TimeZone 关于时间的几个使用类

package com.dcc.core.serxe.test;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;
/**
* Date  Calendar  GregorianCalendar  TimeZone  关于时间的几个使用类
*/
public class DateDemo {

public static void main(String[] args) {

//------------------------> Date()  日期  ------------------------------
//java.util.Date;  java.text.SimpleDateFormat;
Date date = new Date(System.currentTimeMillis());
Date dt = new Date();
//date=dt : Thu Nov 23 18:46:46 CST 2017

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS");
String f = format.format(date);
String g = format.format(dt);
//f : 2017-11-23 18:48:34:517     //格式化之后的时间

long time = date.getTime();
//time : 1511434179892            //距 1970年1月1日格林尼治标准时间

long currentTimeMillis = System.currentTimeMillis();
//System.currentTimeMillis() 获得的是自1970-1-01 00:00:00.000 到当前时刻的时间距离,类型为long

//----------------------- --> Calendar  日历-------------------------------
//java.util.Calendar;
Calendar instance = Calendar.getInstance();  //创建日历实例
String months[] = {"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"};

System.out.print("Date: ");
System.out.print(months[instance.get(Calendar.MONTH)]);    //获取月
System.out.print(" " + instance.get(Calendar.DATE) + " "); //获取日
System.out.println(instance.get(Calendar.YEAR));           //获取月

System.out.print("Time: ");
System.out.print(instance.get(Calendar.HOUR) + ":");       //获取小时
System.out.print(instance.get(Calendar.MINUTE) + ":");     //获取分钟
System.out.println(instance.get(Calendar.SECOND));         //获取分钟

instance.set(Calendar.HOUR, 10);						   //设置时间
instance.set(Calendar.MINUTE, 29);                         //设置分钟
instance.set(Calendar.SECOND, 22);						   //设置秒

System.out.print("Updated time: ");
System.out.print(instance.get(Calendar.HOUR) + ":");
System.out.print(instance.get(Calendar.MINUTE) + ":");
System.out.println(instance.get(Calendar.SECOND));

//-----------------------new GregorianCalendar() --> 标准的阳历---------------------------------
//java.util.GregorianCalendar;
String months1[] = {"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"};
int year;
GregorianCalendar gcalendar = new GregorianCalendar();
System.out.print("Date: ");
System.out.print(months1[gcalendar.get(Calendar.MONTH)]);
System.out.print(" " + gcalendar.get(Calendar.DATE) + " ");
System.out.println(year = gcalendar.get(Calendar.YEAR));

System.out.print("Time: ");
System.out.print(gcalendar.get(Calendar.HOUR) + ":");
System.out.print(gcalendar.get(Calendar.MINUTE) + ":");
System.out.println(gcalendar.get(Calendar.SECOND));

//new GregorainCalendar().isLeapYear(int year)        //判断是闰年
if(gcalendar.isLeapYear(2017)) {
System.out.println("The current year is a leap year");
}
else {
System.out.println("The current year is not a leap year");
}

//-----------------------TimeZone --> 时区 ---------------------------------
// TimeZone类 允 许给 出相 对于 格 林威 治 时间（GMT），也称为世界时间（UTC）的时区差
//java.util.TimeZone;
String[] ids = TimeZone.getAvailableIDs();          //获取所有的时区
for (int i = 0; i < ids.length; i++) {
System.out.println(ids[i]);
}
//获取当前所在地的时区
Calendar cal = Calendar.getInstance();
TimeZone timeZone = cal.getTimeZone();
//timeZone.getDisplayName() 中国标准时间
//timeZone.getID()  获得当前时区  Asia/Shanghai
System.out.println(timeZone.getID());

}
}