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深入解析：微服务项目-＞在线oj系统(Java-Spring)--增删改

news 2026/3/27 0:41:11

后端代码

增添

toR

QuestionAddDTO

了解前端添加一个问题需要我们传入什么数据

package com.bite.system.model.question.DTO;
import lombok.Getter;
import lombok.Setter;
@Getter
@Setter
public class QuestionAddDTO {private String title;private Integer difficulty;private Long timeLimit;private Long spaceLimit;private String content;private String questionCase;private String defaultCode;private String mainFuc;
}

Controller

  @PostMapping("/add")public R add(@RequestBody QuestionAddDTO questionAddDTO){return toR(questionService.add(questionAddDTO)) ;}

Service

首先通过mapper进行查询，查询我们的数据库里面是否存在相同标题的题目，如果有，抛出异常，然后异常统一捕获，返回给前端报错

如果所增加题目并不在数据库里面，则新创建一个Question对象，然后将我们前端传来参数（DTO）复制给question对象，然后让数据库进行插入操作

    @Overridepublic int add(QuestionAddDTO questionAddDTO) {List list=questionMapper.selectList(new LambdaQueryWrapper().eq(Question::getTitle,questionAddDTO.getTitle()));if(CollectionUtil.isNotEmpty(list)){throw new ServiceException(ResultCode.FAILED_ALREADY_EXISTS);}Question question = new Question();BeanUtil.copyProperties(questionAddDTO, question);int insert = questionMapper.insert(question);return insert;}

如果插入成功，新增数据将会出现在我们列表的第一个，否则传给前端错误原因

修改

@Data
public class QuestionEditDTO extends QuestionAddDTO{private Long questionId;
}

当我们点开修改页面的时候，会根据id自动获取到相关的详细内容

  @GetMapping("/detail")public R detail(Long questionId) {return R.ok(questionService.detail(questionId));}

首先通过id进行查询，看是否存在这本书，如果不存在抛出异常

如果数据库中有该题，则从数据库里面查询到数据，然后创建一个返回给前端的VO

@Data
public class QuestionDetailVO {private Long questionId;private String title;private Integer difficulty;private Long timeLimit;private Long spaceLimit;private String content;private String questionCase;private String defaultCode;private String mainFuc;
}

然后将值复制给这个VO类，返回VO

 @Overridepublic QuestionDetailVO detail(Long questionId) {Question question = questionMapper.selectById(questionId);if (question == null) {throw new ServiceException(ResultCode.FAILED_NOT_EXISTS);}QuestionDetailVO questionDetailVO = new QuestionDetailVO();BeanUtil.copyProperties(question, questionDetailVO);return questionDetailVO;}

然后继续进行修改操作

  //  /question/edit@PutMapping("/edit")public R edit(@RequestBody QuestionEditDTO questionEditDTO) {return toR(questionService.edit(questionEditDTO));}

通过前端的输入框获得数据，然后点击按键去进行调用后端函数，将参数传入赋值

  @Overridepublic int edit(QuestionEditDTO questionEditDTO) {Question oldQuestion = questionMapper.selectById(questionEditDTO.getQuestionId());if (oldQuestion == null) {throw new ServiceException(ResultCode.FAILED_NOT_EXISTS);}oldQuestion.setTitle(questionEditDTO.getTitle());oldQuestion.setDifficulty(questionEditDTO.getDifficulty());oldQuestion.setTimeLimit(questionEditDTO.getTimeLimit());oldQuestion.setSpaceLimit(questionEditDTO.getSpaceLimit());oldQuestion.setContent(questionEditDTO.getContent());oldQuestion.setQuestionCase(questionEditDTO.getQuestionCase());oldQuestion.setDefaultCode(questionEditDTO.getDefaultCode());oldQuestion.setMainFuc(questionEditDTO.getMainFuc());return questionMapper.updateById(oldQuestion);}

通过id去搜索搜索之前存入的数据，如果不存在抛出异常，

然后对之前的内容进行赋值，之后使用Mapper进行修改

删除

有了前面俩个的学习，我们接下来就会轻松许多，我们这里后端只做第三步

直接通过id去数据库进行删除操作

    //  /question/delete@DeleteMapping("/delete")public R delete(Long questionId) {return toR(questionService.delete(questionId));}

 @Overridepublic int delete(Long questionId) {Question question = questionMapper.selectById(questionId);if (question == null) {throw new ServiceException(ResultCode.FAILED_NOT_EXISTS);}return questionMapper.deleteById(questionId);}