@RequestMapping("/insert") //插入数据 public String save(ApartmentExchange apartmentExchange) throws ParseException { SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd HH:mm"); apartmentExchange.setExchangeTime(sdf1.parse(apartmentExchange.getExchangeTimeStr().replaceAll("T"," "))); Student student = studentService.getById(apartmentExchange.getStuNum()); if (ObjectUtils.isEmpty(student.getDormitoryId())){ student.setDormitoryId(apartmentExchange.getNewApartmentId()); studentService.updateById(student); Dormitory dormitory = dormitoryService.getById(apartmentExchange.getNewApartmentId()); dormitory.setNum(dormitory.getNum()+1); dormitoryService.save(dormitory); }else { Dormitory dormitory = dormitoryService.getById(student.getDormitoryId()); dormitory.setNum(dormitory.getNum()-1); dormitoryService.updateById(dormitory); student.setDormitoryId(apartmentExchange.getNewApartmentId()); studentService.updateById(student); Dormitory dormitory1 = dormitoryService.getById(apartmentExchange.getNewApartmentId()); dormitory1.setNum(dormitory1.getNum()+1); dormitoryService.updateById(dormitory1); } return "redirect:list"; }请详细解释每一行代码
时间: 2023-06-26 19:05:58 浏览: 78
好的,来一行一行解释这段代码:
```
@RequestMapping("/insert") //插入数据
public String save(ApartmentExchange apartmentExchange) throws ParseException {
```
这是一个用于处理 HTTP POST 请求的控制器方法,它被映射到了 "/insert" 路径。当有 POST 请求发送到这个路径时,这个方法将被调用。它接收一个名为 "apartmentExchange" 的 ApartmentExchange 对象作为参数,并且可能会抛出一个 ParseException 异常。
```
SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd HH:mm");
apartmentExchange.setExchangeTime(sdf1.parse(apartmentExchange.getExchangeTimeStr().replaceAll("T"," ")));
```
这两行代码创建了一个 SimpleDateFormat 对象,它被用于将字符串转换成日期对象。然后,它使用这个日期格式对传入的 "apartmentExchange" 对象中的 "exchangeTimeStr" 字段进行解析,并将解析后的日期对象设置回 "apartmentExchange" 对象的 "exchangeTime" 字段。
```
Student student = studentService.getById(apartmentExchange.getStuNum());
```
这一行代码从数据库中获取了一个名为 "studentService" 的服务的实例,并使用传入的 "apartmentExchange" 对象中的 "stuNum" 字段获取了一个名为 "student" 的 Student 对象。
```
if (ObjectUtils.isEmpty(student.getDormitoryId())){
student.setDormitoryId(apartmentExchange.getNewApartmentId());
studentService.updateById(student);
Dormitory dormitory = dormitoryService.getById(apartmentExchange.getNewApartmentId());
dormitory.setNum(dormitory.getNum()+1);
dormitoryService.save(dormitory);
}else {
Dormitory dormitory = dormitoryService.getById(student.getDormitoryId());
dormitory.setNum(dormitory.getNum()-1);
dormitoryService.updateById(dormitory);
student.setDormitoryId(apartmentExchange.getNewApartmentId());
studentService.updateById(student);
Dormitory dormitory1 = dormitoryService.getById(apartmentExchange.getNewApartmentId());
dormitory1.setNum(dormitory1.getNum()+1);
dormitoryService.updateById(dormitory1);
}
```
这是一段包含条件分支的代码,它根据 "student" 对象是否有 "dormitoryId" 来执行不同的操作。
如果 "student" 对象没有 "dormitoryId",则将 "newApartmentId" 字段的值设置为 "student" 对象的 "dormitoryId" 字段,并更新数据库中的 "student" 对象。然后,从数据库中获取一个名为 "dormitoryService" 的服务的实例,并使用 "newApartmentId" 字段的值获取一个名为 "dormitory" 的 Dormitory 对象。最后,将 "dormitory" 对象的 "num" 字段加 1,并将其保存回数据库中。
如果 "student" 对象有 "dormitoryId",则首先从数据库中获取一个名为 "dormitoryService" 的服务的实例,并使用 "dormitoryId" 字段的值获取一个名为 "dormitory" 的 Dormitory 对象。然后,将 "dormitory" 对象的 "num" 字段减 1,并将其保存回数据库中。接下来,将 "newApartmentId" 字段的值设置为 "student" 对象的 "dormitoryId" 字段,并更新数据库中的 "student" 对象。最后,从数据库中获取一个名为 "dormitoryService" 的服务的实例,并使用 "newApartmentId" 字段的值获取一个名为 "dormitory1" 的 Dormitory 对象。将 "dormitory1" 对象的 "num" 字段加 1,并将其保存回数据库中。
```
return "redirect:list";
```
最后,这一行代码将 HTTP 响应重定向到 "/list" 路径,这将由另一个控制器方法来处理。
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