29.课程分类添加功能

一、数据库导入

CREATE TABLE `edu_subject` (
  `id` char(19) NOT NULL COMMENT '课程类别ID',
  `title` varchar(10) NOT NULL COMMENT '类别名称',
  `parent_id` char(19) NOT NULL DEFAULT '0' COMMENT '父ID',
  `sort` int(10) unsigned NOT NULL DEFAULT '0' COMMENT '排序字段',
  `gmt_create` datetime NOT NULL COMMENT '创建时间',
  `gmt_modified` datetime NOT NULL COMMENT '更新时间',
  PRIMARY KEY (`id`),
  KEY `idx_parent_id` (`parent_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 ROW_FORMAT=COMPACT COMMENT='课程科目';

二、课程分类功能

1、引入easyexcel依赖

    <dependencies>
        <!-- https://mvnrepository.com/artifact/com.alibaba/easyexcel -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>2.1.4</version>
        </dependency>
    </dependencies>

2、使用代码生成器生成课程分类代码

 

 只需要更改表名即可

3、创建实体类和excel对应关系

@Data
public class SubjectData {

    @ExcelProperty(index = 0)
    private String oneSubjectName;//第一列

    @ExcelProperty(index = 1)
    private String twoSubjectName;//第二列
}

4、编写EduSubjectController代码

@RestController
@RequestMapping("/eduservice/edu-subject")
public class EduSubjectController {
    @Autowired
    private EduSubjectService subjectService;

//    添加课程分类
    //获取上传过来的文件，把文件读取出来
    @PostMapping("addSubject")
    public R addSubject(MultipartFile file){
        //上传过来的文件
        subjectService.saveSubject(file, subjectService);
        return R.ok();
    }
}

5、编写对应的EduSubjectService接口代码

public interface EduSubjectService extends IService<EduSubject> {

    void saveSubject(MultipartFile file, EduSubjectService subjectService);
}

　　传入EduSubjectService对象是为了后面监听器调用

6.编写接口实现类EduSubjectServiceImpl代码

//添加课程分类
    @Override
    public void saveSubject(MultipartFile file, EduSubjectService subjectService) {
        try{
            //文件输入流
            InputStream in = file.getInputStream();
            //调用方法进行读取
            EasyExcel.read(in, SubjectData.class, new SubjectExcelListener(subjectService)).sheet().doRead();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

　　使用EasyExcel.read对excel的数据进行读取，参数SubjectData.class为与excel对应的实体类，监听器new SubjectExcelListener用于读取并保存数据

7、监听器实现

public class SubjectExcelListener extends AnalysisEventListener<SubjectData> {

    //因为SubjectExcelListener不能交给spring进行管理(即@service)，需要自己new,不能注入其他对象
    //不能实现数据库操作，需要手动的jdbc
    public EduSubjectService subjectService;

    public SubjectExcelListener() {}
    public SubjectExcelListener(EduSubjectService eduSubjectService) {
        this.subjectService = eduSubjectService;
    }

    //读取excel内容，一行一行进行读取
    @Override
    public void invoke(SubjectData subjectData, AnalysisContext analysisContext) {
        if(subjectData == null) {
            throw new GuliException(20001,"文件数据为空");
        }

        //一行一行读取，每次读取都有两个值，第一个为一级分类，第二个为二级分类
        //判断一级分类是否重复
        EduSubject existOneSubject = this.existOneSubject(subjectService, subjectData.getOneSubjectName());
        if (existOneSubject == null){ //没有相同的一级分类，则添加
            existOneSubject = new EduSubject();
            existOneSubject.setParentId("0");
            existOneSubject.setTitle(subjectData.getOneSubjectName());//一级分类名称
            subjectService.save(existOneSubject);
        }

        //获取一级分类id值
        String pid = existOneSubject.getId();
        //添加二级分类
        //判断二级分类是否重复
        EduSubject existTwoSubject = this.existTwoSubject(subjectService, subjectData.getTwoSubjectName(),pid);
        if (existTwoSubject == null){ //没有相同的二级分类，则添加
            existTwoSubject = new EduSubject();
            existTwoSubject.setParentId(pid);
            existTwoSubject.setTitle(subjectData.getTwoSubjectName());//二级分类名称
            subjectService.save(existTwoSubject);
        }

    }

    //判断一级分类不能重复添加
    private EduSubject existOneSubject(EduSubjectService subjectService,String name) {
        QueryWrapper<EduSubject> wrapper = new QueryWrapper<>();
        wrapper.eq("title",name);
        wrapper.eq("parent_id","0");
        EduSubject oneSubject = subjectService.getOne(wrapper);
        return oneSubject;
    }
    //判断二级分类不能重复添加
    private EduSubject existTwoSubject(EduSubjectService subjectService,String name,String pid) {
        QueryWrapper<EduSubject> wrapper = new QueryWrapper<>();
        wrapper.eq("title",name);
        wrapper.eq("parent_id",pid);
        EduSubject twoSubject = subjectService.getOne(wrapper);
        return twoSubject;
    }

    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {

    }
}

　　excel数据：

对excel进行一行行遍历，首先判断一级分类在数据库中是否存在，不存在则添加，置parent_id为0，存在则不做操作。

进而判断二级分类是否存在，存在则添加，置parent_id为一级分类的id，存在则不做操作。

最终保存到数据库中：