Java进行excel的导入导出操作

excel表格的导出导入在业务中经常会遇到，下面介绍hutool和easyExcel两种操作excel的工具

测试的实体类

通过mybatis-plus生成的，用于导出数据的实体类

@Getter
@Setter
@TableName("device_info")
@ApiModel(value = "DeviceInfo对象", description = "")
public class DeviceInfo implements Serializable {

    @ApiModelProperty("设备ID")
    @TableId(value = "device_id",type = IdType.ASSIGN_UUID)
    private String deviceId;

    @ApiModelProperty("设备名称")
    @TableField("device_name")
    private String deviceName;

    @ApiModelProperty("设备编号")
    @TableField("device_no")
    private String deviceNo;

    @ApiModelProperty("设备型号")
    @TableField("device_model")
    private String deviceModel;

    @ApiModelProperty("新建时间")
    @TableField("create_time")
    private LocalDateTime createTime;

    @ApiModelProperty("更新时间")
    @TableField("update_time")
    private LocalDateTime updateTime;

    @ApiModelProperty("创建人")
    @TableField("created_by")
    private String createdBy;

    @ApiModelProperty("更新人")
    @TableField("updated_by")
    private String updatedBy;

    @ApiModelProperty("版本")
    @TableField("version")
    private Long version;

}

Mapper文件

package com.example.demo.mapper;

import com.example.demo.entity.DeviceInfo;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface DeviceInfoMapper extends BaseMapper<DeviceInfo> {

}

Mapper的xml文件

<?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="com.example.demo.mapper.DeviceInfoMapper">

    <!-- 通用查询映射结果 -->
    <resultMap id="BaseResultMap" type="com.example.demo.entity.DeviceInfo">
        <id column="device_id" property="deviceId" />
        <result column="device_name" property="deviceName" />
        <result column="device_no" property="deviceNo" />
        <result column="device_model" property="deviceModel" />
        <result column="create_time" property="createTime" />
        <result column="update_time" property="updateTime" />
        <result column="created_by" property="createdBy" />
        <result column="updated_by" property="updatedBy" />
        <result column="version" property="version" />
    </resultMap>

    <!-- 通用查询结果列 -->
    <sql id="Base_Column_List">
        device_id, device_name, device_no, device_model, create_time, update_time, created_by, updated_by, version
    </sql>

</mapper>

IService接口

package com.example.demo.service;

import com.example.demo.entity.DeviceInfo;
import com.baomidou.mybatisplus.extension.service.IService;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;

public interface IDeviceInfoService extends IService<DeviceInfo> {

    void exportExcel(HttpServletResponse response) throws IOException;

    boolean importExcel(InputStream inputStream);
}

1、使用hutool导出

优点：hutool有很多工具类，包括ExcelWrite和ExcelReader工具类，写代码也很简洁，我觉得简单的导入导出优先可以使用
缺点：导出不支持excel模板，很难将一些特定数据放在特定的单元格中，导入不好读表格的特殊信息，如批注信息等

增加依赖

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.7.22</version>
</dependency>

导入的表格

导出的表格

如果要好看的格式、列宽、行距，可以通过以下代码设置单元格的格式，

StyleSet style = writer.getStyleSet();
style.getHeadCellStyle().setFillBackgroundColor(IndexedColors.WHITE.getIndex());
writer.getCell(0,0).getCellStyle().setFillForegroundColor(IndexedColors.WHITE.getIndex());

代码实现

以下是controller类

package com.example.demo.controller;

import com.example.demo.service.IDeviceInfoService;
import io.swagger.annotations.ApiOperation;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@RestController
@RequestMapping("/device-info")
public class DeviceInfoController {

    @Resource
    private IDeviceInfoService deviceInfoService;

    @GetMapping("/exportExcel")
    @ApiOperation(value = "导出模板表格测试")
    public void exportExcel(HttpServletResponse response) throws IOException {
        deviceInfoService.exportExcel(response);
    }

    @PostMapping("importExcel")
    @ApiOperation(value = "导入表格测试")
    public boolean importExcel(MultipartFile file) throws IOException {
        return deviceInfoService.importExcel(file.getInputStream());
        }
}

以下是进行简单导入导出操作的Service

package com.example.demo.service.impl;

import cn.hutool.poi.excel.ExcelReader;
import cn.hutool.poi.excel.ExcelUtil;
import cn.hutool.poi.excel.ExcelWriter;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.demo.entity.DeviceInfo;
import com.example.demo.mapper.DeviceInfoMapper;
import com.example.demo.service.IDeviceInfoService;
import io.swagger.annotations.ApiModelProperty;
import org.springframework.stereotype.Service;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.net.URLEncoder;
import java.time.LocalDate;
import java.util.List;

@Service
public class DeviceInfoServiceImpl extends ServiceImpl<DeviceInfoMapper, DeviceInfo> implements IDeviceInfoService {

    @Override
    public void exportExcel(HttpServletResponse response) throws IOException {

        //导出的表格名称
        String targetFileName = "测试导出表格" + LocalDate.now();
        String suffix = ".xlsx";

        //设置接口响应结果格式
        response.reset();
        //response为HttpServletResponse对象
        response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        response.addHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode(targetFileName + suffix, "UTF-8"));

        List<DeviceInfo> deviceInfoList = this.list();

        // 通过工具类创建writer，默认创建xls格式
        ExcelWriter writer = ExcelUtil.getWriter();

        //获取注解的值，跟excel表的表头对应
        Field[] fields = DeviceInfo.class.getDeclaredFields();
        for (int i = 0; i < fields.length; i++) {
            String header = fields[i].getDeclaredAnnotation(ApiModelProperty.class).value();
            writer.addHeaderAlias( fields[i].getName(),header);
        }
        //可以新建sheet，将数据导出成多个sheet
        writer.setSheet("设备信息");
// 一次性写出内容，使用默认样式
        writer.write(deviceInfoList);

        //根据单元格内容自动调整列宽
        writer.autoSizeColumnAll();
//out为OutputStream，需要写出到的目标流
        writer.flush(response.getOutputStream());
// 关闭writer，释放内存
        writer.close();

    }

    @Override
    public boolean importExcel(InputStream inputStream) {
        ExcelReader reader = ExcelUtil.getReader(inputStream, 0);
        //获取注解的值，跟excel表的表头对应
        Field[] fields = DeviceInfo.class.getDeclaredFields();
        for (int i = 0; i < fields.length; i++) {
            String header = fields[i].getDeclaredAnnotation(ApiModelProperty.class).value();
            reader.addHeaderAlias(header, fields[i].getName());
        }

        List<DeviceInfo> deviceInfoList = reader.read(0, 1, DeviceInfo.class);

        return this.saveOrUpdateBatch(deviceInfoList);
    }
}

2、使用easyExcel导出

增加依赖

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>3.2.1</version>
</dependency>

导入的表格

导出的表格

预先做好的导出模板

这是进行导出的模板，需要在每一个单元格写上实体的字段名称，程序才能精确将数据填到相应的位置
如{.deviceId}在字段名称前有个 . 表示数据是一个List，如{listSize}表示数据只是一个单元格的值

导出的模板文件放在资源下面

导出的表格结果

代码实现

Controller类

package com.example.demo.controller;

import com.alibaba.excel.EasyExcel;
import com.example.demo.entity.DeviceInfo;
import com.example.demo.listener.DeviceInfoListener;
import com.example.demo.service.IDeviceInfoService;
import io.swagger.annotations.ApiOperation;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@RestController
@RequestMapping("/device-info")
public class DeviceInfoController {

    @Resource
    private IDeviceInfoService deviceInfoService;

    @GetMapping("/exportExcel")
    @ApiOperation(value = "导出模板表格测试")
    public void exportExcel(HttpServletResponse response) throws IOException {
        deviceInfoService.exportExcel(response);
    }

    @PostMapping("importExcel")
    @ApiOperation(value = "导入表格测试")
    public boolean importExcel(MultipartFile file) throws IOException {
        EasyExcel.read(file.getInputStream(),DeviceInfo.class,new DeviceInfoListener(deviceInfoService)).sheet().doRead();
        return true;
    }
}

实现导出逻辑的Service类

package com.example.demo.service.impl;

import cn.hutool.poi.excel.ExcelReader;
import cn.hutool.poi.excel.ExcelUtil;
import com.alibaba.excel.EasyExcelFactory;
import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.write.metadata.WriteSheet;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.demo.entity.DeviceInfo;
import com.example.demo.mapper.DeviceInfoMapper;
import com.example.demo.service.IDeviceInfoService;
import io.swagger.annotations.ApiModelProperty;
import org.springframework.core.io.ClassPathResource;
import org.springframework.stereotype.Service;

import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.net.URLEncoder;
import java.time.LocalDate;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Service
public class DeviceInfoServiceImpl extends ServiceImpl<DeviceInfoMapper, DeviceInfo> implements IDeviceInfoService {

    @Override
    public void exportExcel(HttpServletResponse response) throws IOException {
        //导出的表格名称
        String targetFileName = "测试导出表格" + LocalDate.now();
        String suffix = ".xlsx";
        //根据相对路径获取模板表格的内容
        ClassPathResource resource = new ClassPathResource("template/测试导出模板表格.xlsx");
        File bathFile = resource.getFile();
        //设置接口响应结果格式
        response.reset();
        //response为HttpServletResponse对象
        response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        response.addHeader("Content-Disposition", "attachment;fileName=" + URLEncoder.encode(targetFileName + suffix, "UTF-8"));

        List<DeviceInfo> deviceInfoList = this.list();

        Map<String,Object> map = new HashMap<>();
        map.put("listSize",deviceInfoList.size() );
        map.put("nowDate",LocalDate.now() );

        //将模板复制到目标表格中
        ExcelWriter excelWriter = EasyExcelFactory.write(response.getOutputStream()).withTemplate(bathFile).build();
        //将列表的值写入表格中，要求实体类的字段名称与模板中的名称一致
        WriteSheet sheet = EasyExcelFactory.writerSheet().build();
        excelWriter.fill(map,sheet);
        excelWriter.fill(deviceInfoList, sheet);
        excelWriter.finish();
    }

}

导入需要写一个数据监听类，实现readListener接口

package com.example.demo.listener;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.read.listener.ReadListener;
import com.alibaba.excel.util.ListUtils;
import com.alibaba.fastjson.JSON;
import com.example.demo.entity.DeviceInfo;
import com.example.demo.service.IDeviceInfoService;
import lombok.extern.slf4j.Slf4j;

import java.util.List;

@Slf4j
public class DeviceInfoListener implements ReadListener<DeviceInfo> {

    /**
     * 每隔100条存储数据库，然后清理list ，方便内存回收
     */
    private static final int BATCH_COUNT = 100;
    /**
     * 缓存的数据
     */
    private List<DeviceInfo> cachedDataList = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);

    private IDeviceInfoService deviceInfoService;

    public DeviceInfoListener( ) {
    }

    public DeviceInfoListener(IDeviceInfoService deviceInfoService) {
        this.deviceInfoService = deviceInfoService;
    }
    @Override
    public void invoke(DeviceInfo data, AnalysisContext context) {
        log.info("解析到一条数据:{}", JSON.toJSONString(data));
        cachedDataList.add(data);
        // 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 (cachedDataList.size() >= BATCH_COUNT) {
            saveData();
            // 存储完成清理 list
            cachedDataList = ListUtils.newArrayListWithExpectedSize(BATCH_COUNT);
        }
    }

    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
// 这里也要保存数据，确保最后遗留的数据也存储到数据库
        saveData();
        log.info("所有数据解析完成！");
    }

    /**
     * 加上存储数据库
     */
    private void saveData() {
        log.info("{}条数据，开始存储数据库！", cachedDataList.size());
        deviceInfoService.saveOrUpdateBatch(cachedDataList);
        log.info("存储数据库成功！");
    }
}