java利用easyexcel实现导入与导出功能

    <!-- EasyExcel -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>easyexcel</artifactId>
            <version>2.2.0-beta2</version>
        </dependency>

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="cn.demo.mapper.MedicnesMapper">
    <insert id="saveMedicnesList" parameterType="cn.demo.entity.Medicnes">
        insert into medices
        (food,remark)
        values
        <foreach collection="list" item="rm" separator=",">
            (#{rm.food},#{rm.remark})
        </foreach>
    </insert>
    <select id="medicnesList" parameterType="cn.demo.entity.Medicnes" resultType="cn.demo.entity.Medicnes">
        SELECT
        food,
        remark
        FROM
        medices
    </select>
</mapper>

package cn.demo.entity;

import com.alibaba.excel.annotation.ExcelProperty;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
 @Data
@AllArgsConstructor
@NoArgsConstructor
public class Medicnes {
    @ExcelProperty("食物名称")
    private String  food;
 
    @ExcelProperty("食物产地")
    private String  remark;
}

package cn.demo.config;
 
import cn.demo.entity.Medicnes;
import cn.demo.service.EmpService;
import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;
import org.springframework.beans.factory.annotation.Autowired;
 
import java.util.ArrayList;
import java.util.List;
/**
 * 有个很重要的点 ExcelListener
 * 不能被spring管理，要每次读取excel都要new,然后里面用到spring可以构造方法传进去
 */
public class ExcelListener extends AnalysisEventListener<Medicnes> {
 
    private List<Medicnes> list = new ArrayList<>();
 
    //每隔5条存储数据库，实际使用中可以3000条，然后清理list ，方便内存回收
    private static final int BATCH_COUNT = 5;
 
    //假设这个是一个DAO，当然有业务逻辑这个也可以是一个service。当然如果不用存储这个对象用
    @Autowired
    private EmpService empService;
     /**
     * 如果使用了spring,请使用这个构造方法。
     * 每次创建Listener的时候需要把spring管理的类传进来
     */
    public ExcelListener(EmpService empService) {
        this.empService = empService;
    }
    /**
     * 这个每一条数据解析都会来调用
     */
    @Override
    public void invoke(Medicnes goods, AnalysisContext analysisContext) {
        System.out.println("解析到一条数据:========================"+goods.toString());
        // 数据存储到data，供批量处理或后续自己业务逻辑处理。
        list.add(goods);
        // 达到BATCH_COUNT了，需要去存储一次数据库，防止数据几万条数据在内存，容易OOM
        if(list.size() >= BATCH_COUNT){
            saveData();
            // 存储完成清理data
            list.clear();
        }
 
    }
    /**
     * 所有数据解析完成了 都会来调用
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {
        //确保所有数据都能入库
        saveData();
    }
    /**
     * 加上存储数据库
     */
    private void saveData() {
        System.out.println("=============================="+list.size()+"条数据，开始存储到数据库");
        empService.saveMedicnesList(list);
    }
}

public class DownExcel {
    public static void download(HttpServletResponse response, Class t, List list) throws IOException, IllegalAccessException,InstantiationException {
        response.setContentType("application/vnd.ms-excel");// 设置文本内省
        response.setCharacterEncoding("utf-8");// 设置字符编码
        response.setHeader("Content-disposition", "attachment;filename=demo.xlsx"); // 设置响应头
        EasyExcel.write(response.getOutputStream(), t).sheet("模板").doWrite(list); //用io流来写入数据
    }
}
 
//导出为Excel
@RequestMapping("/downloadexcel.do")
public void getExcel(HttpServletResponse response) throws IllegalAccessException, IOException, 
InstantiationException {
    List<Medicnes> list = sysUserService.medicnesList();
    DownExcel.download(response,Medicnes.class,list);
}

//导入Excel
@RequestMapping("/importexcel.do")
@ResponseBody
public String importexcel(@RequestParam(value = "excelFile") MultipartFile file) throws IOException{
    EasyExcel.read(file.getInputStream(), Medicnes.class, new ExcelListener(sysUserService)).sheet().doRead();
    return "success";
}