开发中遇到的问题

- 一.Mybatis
- - 1.链式SQL嵌套and,or
  - 2.xml
  - 3.分页
- 二.SpringBoot
- - 1.定时任务
- 三.Java
- - 1.常用的流
  - 2.时间格式转换
  - 3.JSON问题
- 四.Windows
- - 1.杀死端口
- 未完待续......

一.Mybatis

1.链式SQL嵌套and,or

 List<UserMeetDO> meets = userMeetMapper.selectList(new LambdaQueryWrapper<UserMeetDO>().eq(UserMeetDO::getMeetId, userMeetVo.getMeetId()).and(wrapper -> wrapper.and(w -> w.le(UserMeetDO::getStartTime, userMeetVo.getStartTime()).gt(UserMeetDO::getEndTime, userMeetVo.getStartTime())).or(w -> w.lt(UserMeetDO::getStartTime, userMeetVo.getEndTime()).ge(UserMeetDO::getEndTime, userMeetVo.getEndTime())).or(w -> w.ge(UserMeetDO::getStartTime,  userMeetVo.getStartTime()).le(UserMeetDO::getEndTime, userMeetVo.getEndTime()))));

2.xml

在xml中mybatis里认为0就是空字符串

if和foreach

 	 <if test="deptIds != null">and (sl.dept_id in<foreach collection="deptIds" open="(" close=")" separator="," item="id">#{id}</foreach>or sl.owner_id in<foreach collection="deptIds" open="(" close=")" separator="," item="id">#{id}</foreach>)</if>

3.分页

中规中矩

 Page<Object> iPage = PageHelper.startPage(page, size);return PageResult.of(iPage,list);

手动分页

 public List<PlanReceiveBo> getPage(List<PlanReceiveBo> list, int pageNum, int pageSize) {List<PlanReceiveBo> result = new ArrayList<>();if (list == null || list.isEmpty()) {return result;}int totalSize = list.size();int totalPage = (totalSize + pageSize - 1) / pageSize;if (pageNum < 1 || pageNum > totalPage) {return result;}int startIndex = (pageNum - 1) * pageSize;int endIndex = Math.min(startIndex + pageSize, totalSize);for (int i = startIndex; i < endIndex; i++) {result.add(list.get(i));}return result;}

二.SpringBoot

1.定时任务

@Scheduled(cron = “0 0 2 * * ?”)
5位：* * * * * 分、时、天、月、周
6位：* * * * * * 秒、分、时、天、月、周
7位：* * * * * * * 秒、分、时、天、月、周、年

三.Java

1.常用的流

  BigDecimal totalAmount = list.stream().map(e -> e.getPlanReceiveAmount()).reduce(BigDecimal.ZERO, BigDecimal::add);

2.时间格式转换

LocalDate->LocalDateTime

param.setApplyStartTime(listParam.getStartTime().atStartOfDay());
param.setApplyEndTime(listParam.getEndTime().atTime(23,59,59));

LocalDateTime->LocalDate

LocalDateTime dateTime = LocalDateTime.of(2023, 11, 17, 10, 30);
LocalDate date = dateTime.toLocalDate();
System.out.println(date); // 输出 2023-11-17

3.JSON问题

如果为空就不返回该字段

@JsonInclude(JsonInclude.Include.NON_EMPTY)

JSON的相互转换

String jsonString = "{\"name\":\"name\", \"age\":20}";
SomeObject someObject = JSON.parseObject(jsonString, SomeObject.class);
SomeObject someObject = new SomeObject("name", 20);
String jsonString = JSON.toJSONString(someObject, SerializerFeature.PrettyFormat);

		
JSONObject jsonObject = new JSONObject(jsonString);
JSONArray attributesArray = jsonObject.getJSONArray("attributes");
JSONObject attributes1 = attributesArray.getJSONObject(0);
String country = attributes1.getString("country");