springboot实现EasyExcel对Excel读和写操作

GitHub地址参照：https://github.com/alibaba/easyexcel

写操作（将数据写入到excel文件）

1.引入依赖

<dependencies>
    <!-- https://mvnrepository.com/artifact/com.alibaba/easyexcel -->
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>easyexcel</artifactId>
        <version>2.1.1</version>
    </dependency>
    <!--xls-->
    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>3.17</version>
    </dependency>

    <dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi-ooxml</artifactId>
        <version>3.17</version>
    </dependency>
</dependencies>

2.创建实体类，这里用的lombok生成get和set。

package com.stu.codeGenerator.excel;

import com.alibaba.excel.annotation.ExcelProperty;
import lombok.Data;

@Data
public class DemoDataExcel {

    //设置Excel表头名称

    @ExcelProperty("学生编号")
    private Integer sno;

    @ExcelProperty("学生姓名")
    private String sname;

}

3.测试方法（两种方式都可以）

方法1

package com.stu.codeGenerator.excel;

import com.alibaba.excel.EasyExcel;

import java.util.ArrayList;
import java.util.List;

public class DemoEasyExcel {

    public static void main(String[] args) {
        //写法1
        //实现excel写的操作（生成一个excel文件，并且有内容）
        //1.设置写入文件地址和excel文件名称，如果路径是C盘可能会报错。
        String fileName = "F:\write.xlsx";

        //2.调用easyexcel里面的方法实现写操作
        //write有两个参数，第一个参数是文件路径名称，第二个参数是实体类class，doWrite里需要传递一个集合
        EasyExcel.write(fileName,DemoDataExcel.class).sheet("学生列表").doWrite(getData());

    }

    private static List<DemoDataExcel> getData(){
        List<DemoDataExcel> list = new ArrayList<>();
        for(int i = 0;i<10;i++){
            DemoDataExcel data = new DemoDataExcel();
            data.setSno(i);
            data.setSname("Excel"+i);
            list.add(data);
        }
        return list;
    }
}

方法2

public static void main(String[] args) throws Exception {
    // 写法2，方法二需要手动关闭流
    String fileName = "F:\112.xlsx";
    // 这里 需要指定写用哪个class去写
    ExcelWriter excelWriter = EasyExcel.write(fileName, DemoDataExcel.class).build();
    WriteSheet writeSheet = EasyExcel.writerSheet("写入方法二").build();
    excelWriter.write(data(), writeSheet);
    /// 千万别忘记finish关闭流
    excelWriter.finish();
}

4.执行main方法，excel效果如下。

读操作基本示例（从excel文件把数据读出来）

1.创建实体类（注解多了一个value和index）

package com.stu.codeGenerator.excel;

import com.alibaba.excel.annotation.ExcelProperty;
import lombok.Data;

@Data
public class DemoDataExcel {

    //设置Excel表头名称

    //0表示第一列
    @ExcelProperty(value = "学生编号",index = 0)
    private Integer sno;

    //1表示第二列
    @ExcelProperty(value = "学生姓名",index = 1)
    private String sname;

}

2.创建一个监听器类继承AnalysisEventListener，进行excel文件读取，他是一行一行的读取

package com.stu.codeGenerator.excel;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;

import java.sql.SQLOutput;
import java.util.Map;

public class ExcelListener extends AnalysisEventListener<DemoDataExcel> {

    //一行一行读取excel内容，第一行表头不会读取
    @Override
    public void invoke(DemoDataExcel demoDataExcel, AnalysisContext analysisContext) {

        System.out.println("++++行内容++++="+demoDataExcel);
    }

    //读取表头内容
    @Override
    public void invokeHeadMap(Map<Integer, String> headMap, AnalysisContext context) {
        System.out.println("+++表头+++++="+headMap);
    }

    //读取完成之后
    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {
        System.out.println("++++++++="+analysisContext);

    }

}

3.测试方法（两个方法）

方法1

package com.stu.codeGenerator.excel;

import com.alibaba.excel.EasyExcel;

import java.util.ArrayList;
import java.util.List;

public class DemoEasyExcel {

    public static void main(String[] args) {
//        //实现excel写的操作（生成一个excel文件，并且有内容）
//        //1.设置写入文件地址和excel文件名称
//        String fileName = "F:\write.xlsx";
//
//        //2.调用easyexcel里面的方法实现写操作
//        //write有两个参数，第一个参数是文件路径名称，第二个参数是实体类class
//        EasyExcel.write(fileName,DemoDataExcel.class).sheet("学生列表").doWrite(getData());
        String fileName = "F:\write.xlsx";
        EasyExcel.read(fileName,DemoDataExcel.class,new ExcelListener()).sheet().doRead();

    }

    private static List<DemoDataExcel> getData(){
        List<DemoDataExcel> list = new ArrayList<>();
        for(int i = 0;i<10;i++){
            DemoDataExcel data = new DemoDataExcel();
            data.setSno(i);
            data.setSname("Excel"+i);
            list.add(data);
        }
        return list;
    }
}

方法2

   public static void main(String[] args) throws Exception {

        // 写法1：
        String fileName = "F:\01.xlsx";
        // 这里 需要指定读用哪个class去读，然后读取第一个sheet 文件流会自动关闭
        EasyExcel.read(fileName, ReadData.class, new ExcelListener()).sheet().doRead();

        // 写法2：
        InputStream in = new BufferedInputStream(new FileInputStream("F:\01.xlsx"));
        ExcelReader excelReader = EasyExcel.read(in, ReadData.class, new ExcelListener()).build();
        ReadSheet readSheet = EasyExcel.readSheet(0).build();
        excelReader.read(readSheet);
        // 这里千万别忘记关闭，读的时候会创建临时文件，到时磁盘会崩的
        excelReader.finish();
}

控制台输出：

+++表头+++++={0=学生编号, 1=学生姓名}
++++行内容++++=DemoDataExcel(sno=0, sname=Excel0)
++++行内容++++=DemoDataExcel(sno=1, sname=Excel1)
++++行内容++++=DemoDataExcel(sno=2, sname=Excel2)
++++行内容++++=DemoDataExcel(sno=3, sname=Excel3)
++++行内容++++=DemoDataExcel(sno=4, sname=Excel4)
++++行内容++++=DemoDataExcel(sno=5, sname=Excel5)
++++行内容++++=DemoDataExcel(sno=6, sname=Excel6)
++++行内容++++=DemoDataExcel(sno=7, sname=Excel7)
++++行内容++++=DemoDataExcel(sno=8, sname=Excel8)
++++行内容++++=DemoDataExcel(sno=9, sname=Excel9)
++++++++=com.alibaba.excel.context.AnalysisContextImpl@491666ad

Process finished with exit code 0

读操作--保存到数据示例（从excel文件把数据读出来，保存到数据库）

SubJectData实体类封装

package com.stu.eduservice.entity.excel;

import com.alibaba.excel.annotation.ExcelProperty;
import lombok.Data;

@Data
public class SubJectData {

    @ExcelProperty(index = 0)
    private String oneSubjectName;

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

controller层

package com.stu.eduservice.controller;

import com.stu.commonutils.ResultData;
import com.stu.eduservice.entity.EduSubject;
import com.stu.eduservice.entity.subject.Subject;
import com.stu.eduservice.service.IEduSubjectService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import org.springframework.web.multipart.MultipartFile;

import java.util.List;

/**
 * <p>
 * 课程科目 前端控制器
 * </p>
 *
 * @author stu
 * @since 2021-05-24
 */
@RestController
@RequestMapping("/eduservice/subject")
@CrossOrigin
public class EduSubjectController {

    @Autowired
    private IEduSubjectService eduSubjectService;

    //添加课程分类
    //获取上传的excel文件，把文件的内容读取出来
    @PostMapping("addSubJect")
    public ResultData addSubJect(MultipartFile file){
        //上传过来的excel文件

        eduSubjectService.addSubJect(file,eduSubjectService);
        return ResultData.success();
    }

    //课程分类列表（树形）
    @GetMapping("getAllSubJect")
    public ResultData getAllSubJect(){
        List<Subject> list = eduSubjectService.getAllSubJect();
        return ResultData.success().data("list",list);
    }


}

service接口

package com.stu.eduservice.service;

import com.stu.eduservice.entity.EduSubject;
import com.baomidou.mybatisplus.extension.service.IService;
import com.stu.eduservice.entity.subject.Subject;
import org.springframework.web.multipart.MultipartFile;

import java.util.List;

/**
 * <p>
 * 课程科目 服务类
 * </p>
 *
 * @author stu
 * @since 2021-05-24
 */
public interface IEduSubjectService extends IService<EduSubject> {

    void addSubJect(MultipartFile file,IEduSubjectService eduSubjectService);

    List<Subject> getAllSubJect();
}

service实现类

package com.stu.eduservice.service.impl;

import com.alibaba.excel.EasyExcel;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.stu.eduservice.entity.EduSubject;
import com.stu.eduservice.entity.excel.SubJectData;
import com.stu.eduservice.entity.subject.Subject;
import com.stu.eduservice.listener.SubJectExcelListener;
import com.stu.eduservice.mapper.EduSubjectMapper;
import com.stu.eduservice.service.IEduSubjectService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;

import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * <p>
 * 课程科目 服务实现类
 * </p>
 *
 * @author stu
 * @since 2021-05-24
 */
@Service
public class EduSubjectServiceImpl extends ServiceImpl<EduSubjectMapper, EduSubject> implements IEduSubjectService {

    @Override
    public void addSubJect(MultipartFile file,IEduSubjectService eduSubjectService) {

        try {
            //文件输入流
            InputStream in = file.getInputStream();
            //调用读方法，通过监听类把数据保存到数据库
            EasyExcel.read(in, SubJectData.class,new SubJectExcelListener(eduSubjectService)).sheet().doRead();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }


    @Override
    public List<Subject> getAllSubJect() {
        List<Subject> root = new ArrayList<Subject>();

        QueryWrapper<EduSubject> wrapper = new QueryWrapper<>();
        List<EduSubject> permissionList = baseMapper.selectList(wrapper);//根菜单

        List<Subject> subjectList = new ArrayList<>();

        Map<String,Subject> map = new HashMap<String,Subject>();
        for(EduSubject bean :permissionList){
            Subject subject = new Subject();
            BeanUtils.copyProperties(bean,subject);
            map.put(bean.getId(), subject);
            subjectList.add(subject);
        }
        for(Subject bean :subjectList){
            Subject children = bean;
            if(bean.getParentId().equals("0")){
                root.add(bean);
            }else{
                Subject parent = map.get(children.getParentId());
                parent.getChildren().add(children);
            }
        }
        return root;
    }
} 

监听类继承AnalysisEventListener，通过invoke方法把数据保存到数据库

package com.stu.eduservice.listener;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.stu.eduservice.entity.EduSubject;
import com.stu.eduservice.entity.excel.SubJectData;
import com.stu.eduservice.service.IEduSubjectService;
import com.stu.servicebase.exceptionHandler.GuliException;

public class SubJectExcelListener extends AnalysisEventListener<SubJectData> {

    //因为SubJectExcelListener不能交给spring进行管理，需要自己new，不能注入其他对象
    //不能实现数据库操作 new mapper

    public IEduSubjectService eduSubjectService;

    //让对象可以使用start,创建一个有参构造和一个无参构造
    public SubJectExcelListener(){}
    public SubJectExcelListener(IEduSubjectService eduSubjectService){
        this.eduSubjectService = eduSubjectService;
    }
    //让对象可以使用end

    @Override
    public void invoke(SubJectData subJectData, AnalysisContext analysisContext) {
        if(subJectData == null ){
            throw new GuliException(20001,"数据为空");
        }
        //一行一行读取，每次读取有两个值，一级分类和二级分类
        EduSubject eduSubjectOne =this.checkOne(eduSubjectService,subJectData.getOneSubjectName());
        if(eduSubjectOne == null ){

            eduSubjectOne = new EduSubject();
            eduSubjectOne.setParentId("0");
            eduSubjectOne.setTitle(subJectData.getOneSubjectName());

            eduSubjectService.save(eduSubjectOne);
        }

        //取得一级分类的id，作为二级分类的父id，pid
        String pid = eduSubjectOne.getId();
        EduSubject eduSubjectTwo =this.checkTwo(eduSubjectService,subJectData.getTwoSubjectName(),pid);

        if(eduSubjectTwo == null ){
            eduSubjectTwo = new EduSubject();
            eduSubjectTwo.setParentId(pid);
            eduSubjectTwo.setTitle(subJectData.getTwoSubjectName());

            eduSubjectService.save(eduSubjectTwo);
        }
    }

    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {

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

    //判断二级分类不能重复
    private EduSubject checkTwo(IEduSubjectService eduSubjectService,String name,String pid){
        QueryWrapper<EduSubject> wrapper = new QueryWrapper<>();
        wrapper.eq("title",name);
        wrapper.eq("parent_id",pid);
        EduSubject eduSubject = eduSubjectService.getOne(wrapper);
        return eduSubject;
    }


}