Java日期时间以及日期相互转换

package com.study.string;

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

public class DateBase {

 public static void main(String[] args) throws ParseException {
  /*
   * 获得当前时间
   */
  Date date1 = new Date();
  long long1 = date1.getTime();//date类型，转为 long类型
  System.out.println(date1);//Sat Aug 26 08:36:36 GMT+08:00 2017
  System.out.println(long1);//1503708031359
  
  Calendar cale1 = Calendar.getInstance();
  date1 = cale1.getTime();//calendar 类型 转为 date类型
  long1 = date1.getTime();
  System.out.println(cale1);
  System.out.println(date1);//Sat Aug 26 08:36:36 GMT+08:00 2017
  System.out.println(long1);
  
  /*
   *设置时间 
   */
  long1 += 24*60*60*1000;
  date1.setTime(long1);
  System.out.println(date1);//Sun Aug 27 08:43:26 GMT+08:00 2017
  
  /*
   * 格式化时间日期,无参数的默认格式，有参数的自定义格式。
   * Date -> String 用 format()
   * String -> Date 用 parse()
   */
  SimpleDateFormat sim1 = new SimpleDateFormat();//默认格式：17-8-27 上午8:45
  String time1 = sim1.format(date1);
  System.out.println(time1);//17-8-27 上午8:45 
  Date date11 = sim1.parse(time1);
  System.out.println(date11);
  
  SimpleDateFormat sim2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss sss");
  String time2 = sim2.format(date1);
  System.out.println(time2);//2017-08-27 08:47:58 058
  Date date22= sim2.parse(time2);
  System.out.println(date22);//Sun Aug 27 08:52:08 GMT+08:00 2017
  
  /*
   * 创建指定日期 String 
   * GregorianCalendar
   */
  SimpleDateFormat sim3 = new SimpleDateFormat("yyyy-MM-dd");
  String str1 = "2014-09-27";
  Date date33 = sim3.parse(str1);
  System.out.println(date33);//Sat Sep 27 00:00:00 GMT+08:00 2014
  
  
  GregorianCalendar gre1 = new GregorianCalendar(2015,Calendar.DECEMBER,25);
  Date date44 = gre1.getTime();
  System.out.println(date44);//Fri Dec 25 00:00:00 GMT+08:00 2015
  
  
  Calendar cal2 = Calendar.getInstance();
  cal2.set(Calendar.YEAR, 2017);
  cal2.set(Calendar.MONTH, 7);//月份的数字与 第几个月差1， 8 == Calendar.SEPTEMBER
  cal2.set(Calendar.DATE, 26);// Tue Sep 09 09:04:25 GMT+08:00 2008
//  cal2.set(Calendar.DAY_OF_MONTH, 12);
  System.out.println(cal2.getTime());//Sat Aug 26 09:09:44 GMT+08:00 2017
  
  
  
  /*
   * 获取年月日，星期，时间
   */
  int dayOfweek = cal2.get(Calendar.DAY_OF_WEEK);
  System.out.println(dayOfweek);//7 是星期六
  
  
  /*
   * Calendar 的时间加减
   */
  Calendar cal3 = Calendar.getInstance();
  cal3.add(Calendar.YEAR, 1);
  cal3.add(Calendar.MONTH, -2);
  System.out.println(cal3.getTime());//Tue Jun 26 09:14:11 GMT+08:00 2018
  
  
  /*
   * 
   */
  Calendar cal4 = Calendar.getInstance();
  cal4.set(Calendar.YEAR, 2016);
  cal4.set(Calendar.DATE, 1);
  //每个月的最后 一天
  for(int month = Calendar.JANUARY;month