添加课程功能的实现

添加课程的思路很简单：上传excel表格实现课程添加，我们需要做下面这些事。

(1)引入easyexcel依赖

(2)使用代码生成器生成实体类对应的controller、service和，mapper。

将CodeGenerator的数据库表改为edu_subject即可。

strategy.setInclude("edu_subject");//根据数据库哪张表生成，有多张表就加逗号继续填写

运行生成代码，如果没有生成试着把CodeGenerator移到启动类同一级目录试试。在生成的controller中添加注解@CrossOrigin解决跨域问题。

(3)编写controller

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

    @PostMapping("/addSubject")
    public R addSubject(MultipartFile file) {
        eduSubjectService.addSubject(file);
        return R.ok();
    }
}

记得在EduSubjectService接口及其实现类中增加addSubject()方法。

(4) 创建实体类

\entity\excel下创建实体类SubjectData 。

@Data
@ToString
public class SubjectData {

    //一级分类
    @ExcelProperty(index = 0)
    private String oneSubjectName;

    //二级分类
    @ExcelProperty(index = 1)
    private String twoSubjectName;
}

(4)读取excel文件

新建包listner,包下建类SubjectExcelListener。

public class SubjectExcelListener extends AnalysisEventListener<SubjectData> {

    //因为SubjectExcelListener不能交给spring进行ioc管理，需要自己手动new，不能注入其他对象
    //不能实现数据库操作

    public EduSubjectService eduSubjectService;

    //有参，传递subjectService用于操作数据库
    public SubjectExcelListener(EduSubjectService eduSubjectService) {
        this.eduSubjectService = eduSubjectService;
    }

    //无参
    public SubjectExcelListener() {
    }

    //读取excel内容，一行一行读取
    @Override
    public void invoke(SubjectData subjectData, AnalysisContext analysisContext) {
        //表示excel中没有数据，就不需要读取了
        if (subjectData==null){
            throw new GuliException(20001,"添加失败");
        }

        //一行一行读取，每次读取有两个值，第一个值一级分类，第二个值二级分类
        //判断是否有一级分类是否重复
        EduSubject existOneSubject = this.existOneSubject(eduSubjectService, subjectData.getOneSubjectName());
        if (existOneSubject == null){ //没有相同的一级分类，进行添加
            existOneSubject = new EduSubject();
            existOneSubject.setParentId("0"); //设置一级分类id值，0代表为一级分类
            existOneSubject.setTitle(subjectData.getOneSubjectName());//设置一级分类名
            eduSubjectService.save(existOneSubject);//给数据库添加一级分类
        }

        //获取一级分类的id值
        String parent_id = existOneSubject.getId();
        //判断是否有耳机分类是否重复
        EduSubject existTwoSubject = this.existTwoSubject(eduSubjectService, subjectData.getTwoSubjectName(), parent_id);
        if (existTwoSubject==null){//没有相同的二级分类，进行添加
            existTwoSubject = new EduSubject();
            existTwoSubject.setParentId(parent_id); //设置二级分类id值
            existTwoSubject.setTitle(subjectData.getTwoSubjectName());//设置二级分类名
            eduSubjectService.save(existTwoSubject);//给数据库添加二级分类
        }

    }


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

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

    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {

    }
}

实现service,注意新增了参数eduSubjectService，对应的controller与接口请自行调整

@Service
public class EduSubjectServiceImpl extends ServiceImpl<EduSubjectMapper, EduSubject> implements EduSubjectService {

    //添加课程分类
    @Override
    public void addSubject(MultipartFile file,EduSubjectService eduSubjectService) {
        try {
            //文件输入流
            InputStream is = file.getInputStream();

            //调用方法进行读取
            EasyExcel.read(is, SubjectData.class,new SubjectExcelListener(eduSubjectService))
                    .sheet().doRead();

        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

还有一个小细节值得注意，就是要把实体类中时间设置为自动填充。

@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
@ApiModel(value="EduSubject对象", description="课程科目")
public class EduSubject implements Serializable {

    private static final long serialVersionUID = 1L;

    @ApiModelProperty(value = "课程类别ID")
    @TableId(value = "id", type = IdType.ID_WORKER_STR)
    private String id;

    @ApiModelProperty(value = "类别名称")
    private String title;

    @ApiModelProperty(value = "父ID")
    private String parentId;

    @ApiModelProperty(value = "排序字段")
    private Integer sort;

    @ApiModelProperty(value = "创建时间")
    @TableField(fill = FieldFill.INSERT)
    private Date gmtCreate;

    @ApiModelProperty(value = "更新时间")
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date gmtModified;


}

使用swagger进行测试即可。