• 当需要对Date时间类型进行加减int类型分钟运算

Date date = new Date();//Sun Mar 06 14:12:14 CST 2022int hour = 25;int minutes = 70;int second = 3;SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");System.out.println(simpleDateFormat.format(date));//初始时间↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑ 2022-03-06 14:23:33 ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑//创建时间工具类Calendar cal = Calendar.getInstance();//设置时间坐标cal.setTime(date);//给时间坐标加上hour小时cal.add(Calendar.HOUR,hour);System.out.println(simpleDateFormat.format(cal.getTime()));//加时时间↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑ 2022-03-07 15:24:12 ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑可以跨天//给时间坐标加上minutes分钟cal.add(Calendar.MINUTE,minutes );System.out.println(simpleDateFormat.format(cal.getTime()));//加分时间↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑ 2022-03-06 16:33:33 ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑可以跨小时//给时间坐标减去second秒cal.add(Calendar.SECOND,-second );System.out.println(simpleDateFormat.format(cal.getTime()));//减秒时间↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑ 2022-03-06 16:33:30 ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑可以跨分钟

• 当需要获取集合中的某个字段的集合

List<Event> event = new ArrayList();Event event1 = new Event();event1.setDeptId(18);event1.setEventType("小明");Event event2 = new Event();event2.setDeptId(19);event2.setEventType("小红");Event event3 = new Event();event3.setDeptId(20);event3.setEventType("小刚");event.add(event1);event.add(event2);event.add(event3);List<String> eventType = event.stream().map(Event::getEventType).collect(Collectors.toList());System.out.println(eventType);//[小明, 小红, 小刚]

• 时间格式化(常用)

@DateTimeFormat(pattern="yyyy-MM-dd HH:mm:ss")
@JSONField(format = "yyyy-MM-dd HH:mm:ss")
//@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
private Date  receiveTime;
//JSONField和JsonFormat使用一个,一个不行换另一个

• 对集合的处理(常用)

  ArrayList<Integer> list = new ArrayList<>();for(int i = 0; i<=10;i++){list.add(i);list.add(i++);}System.out.println(list);//[0, 0, 2, 2, 4, 4, 6, 6, 8, 8, 10, 10]//获取list集合中小于5的元素集合List<Integer> collect = list.stream().filter(i -> (i <= 5)).collect(Collectors.toList());System.out.println(collect);//[0, 0, 2, 2, 4, 4]//做运算List<Integer> collect1 = list.stream().map(i -> ++i).collect(Collectors.toList());System.out.println(collect1);//[1, 1, 3, 3, 5, 5, 7, 7, 9, 9, 11, 11]//去重List<Integer> collect2 = list.stream().distinct().collect(Collectors.toList());System.out.println(collect2);//[0, 2, 4, 6, 8]//返回第几个之前的元素List<Integer> collect3 = list.stream().limit(7).collect(Collectors.toList());System.out.println(collect3);//[0, 0, 2, 2, 4, 4, 6]//获取第几个之后的元素List<Integer> collect4 = list.stream().skip(7)
  .collect(Collectors.toList());System.out.println(collect4);//[6, 8, 8]
  //进阶-根据集合中对象的某个字段去重
  //修改二级单位bugList<DbZone> dbZonesByGroupStreeCode1 = dbZonesByGroupStreeCode.stream().collect(Collectors.collectingAndThen(//去除重复StreetCode/新建ArrayList集合Collectors.toCollection(() -> new TreeSet<>(Comparator.comparing(DbZone::getStreetCode))), ArrayList::new));

  sql通过经纬度搜索范围

• SELECT* 
  FROM(SELECTqj.JJDBH,qj.DHDWJD,qj.DHDWWD,ROUND(6371 * 2 * ASIN(SQRT(POW( SIN(( 入参纬度 * PI()/ 180-纬度字段名 * PI()/ 180 )/ 2 ), 2 )+ COS( 入参纬度 * PI()/ 180 )* COS( 纬度字段名 * PI()/ 180 )* POW( SIN(( 入参经度 * PI()/ 180-经度字段名 * PI()/ 180 )/ 2 ), 2 )))* 1000 ) AS `range` FROM表名) AS sub 
  WHERE`range` < 距离(米)
  ORDER BY`range`