Use cn.hutool.poi.excel to export Excel in java

 If you need to export complex cells and merge cells, please check 

Export Excel in Java, merge cells, easy to get started_SUMMERENT's Blog-CSDN Blog

Table of contents

 1. Introduce maven dependency

2. Write ExportExcelVo

3. Write the ExportUtil export data tool, which supports both xlsx and csv

4. Write ExcelService layer and prepare data

5. Write the controller layer and call the interface

6. Test export

---

 1. Introduce maven dependency

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.3.8</version>
        </dependency>
        <dependency>
            <groupId>cn.jimmyshi</groupId>
            <artifactId>bean-query</artifactId>
            <version>1.1.5</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>

Note: If there is an error below, please check the imported maven dependencies 

2. Write ExportExcelVo

@Data
public class ExportExcelVo {

    private String headOne;

    private String headTwoCome;

    private String headTwoOn;

    private String headThreeCome;

    private String headThreeOn;

    private String headFourCome;

    private String headFourOn;

    private String headFiveCome;

    private String headFiveOn;

}

3. Write the ExportUtil export data tool, which supports both xlsx and csv

import cn.hutool.core.io.IoUtil;
import cn.hutool.poi.excel.ExcelUtil;
import cn.hutool.poi.excel.ExcelWriter;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVPrinter;
import org.apache.commons.io.FilenameUtils;
import org.springframework.util.CollectionUtils;
import cn.jimmyshi.beanquery.BeanQuery;
import springboot.redis.demo.exception.MyRuntimeException;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.util.Collection;
import java.util.List;
import java.util.Map;

/**
 * @Description: 导出数据工具，支持xlsx和csv两种
 * @Title: ExportUtil
 */
@Slf4j
public class ExportUtil {
    /**
     *
     * @param dataList 导出数据列表
     * @param fieldMap 导出的数据字段，key为对象字段名称，value为标题名称
     * @param fileName 导出文件名
     * @return void
     * @throws IOException 文件操作失败
     */
    public static <T> void doExport(Collection<T> dataList, Map<String,String> fieldMap,String fileName) throws IOException{
        if (CollectionUtils.isEmpty(dataList)){
            return;
        }
        StringBuilder sb = new StringBuilder(128);
        for (Map.Entry<String,String> e: fieldMap.entrySet()) {
            sb.append(e.getKey()).append(" as ").append(e.getValue()).append(", ");
        }
        //去掉末尾空格
        String fieldString = sb.substring(0,sb.length() - 2);
        //写出数据到excel格式的输出流,BeanQuery 是一个把对象转换为Map的Java工具库
        List<Map<String,Object>> resultList = BeanQuery.select(fieldString).executeFrom(dataList);
         构建HTTP输出流参数
        HttpServletResponse response = ContextUtil.getHttpResponse();
        response.setHeader("content-type", "application/octet-stream");
        response.setContentType("application/octet-stream");
        response.setHeader("Content-Disposition", "attachment;filename=" + fileName);
        if ("xlsx".equals(FilenameUtils.getExtension(fileName))) {
            ServletOutputStream out = response.getOutputStream();
            ExcelWriter writer = ExcelUtil.getWriter(true);
            writer.setRowHeight(-1, 30);
            writer.setColumnWidth(-1, 30);
            writer.setColumnWidth(1, 20);
            writer.write(resultList);
            writer.flush(out);
            writer.close();
            IoUtil.close(out);

        } else if ("csv".equals(FilenameUtils.getExtension(fileName))) {
            Collection<String> headerList = fieldMap.values();
            String[] headerArray = new String[headerList.size()];
            headerList.toArray(headerArray);
            CSVFormat format = CSVFormat.DEFAULT.withHeader(headerArray);
            response.setCharacterEncoding(StandardCharsets.UTF_8.name());
            try (Writer out = response.getWriter(); CSVPrinter printer = new CSVPrinter(out, format)) {
                for (Map<String, Object> o : resultList) {
                    for (Map.Entry<String, Object> entry : o.entrySet()) {
                        printer.print(entry.getValue());
                    }
                    printer.println();
                }
                printer.flush();
            } catch (Exception e) {
                log.error("Failed to call ExportUtil.doExport", e);
            }
        } else {
            throw new MyRuntimeException("导出文件类型不支持！");
        }
    }

}

ContextUtil class 

import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletResponse;

public class ContextUtil {
    public static HttpServletResponse getHttpResponse() {
        return ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getResponse();
    }
}

4. Write ExcelService layer and prepare data

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

public class ExcelService {
    public static List<ExportExcelVo> getExportData() {
        ExportExcelVo excelVo = new ExportExcelVo();
        List<ExportExcelVo> list = new ArrayList<>();

        for (int i = 0; i < 3; i++) {
            excelVo.setHeadOne("AAA");
            excelVo.setHeadTwoCome("BBB");
            excelVo.setHeadTwoOn("CCC");
            excelVo.setHeadThreeCome("DDD");
            excelVo.setHeadThreeOn("EEE");
            excelVo.setHeadFourCome("FFF");
            excelVo.setHeadFourOn("GGG");
            excelVo.setHeadFiveCome("HHH");
            excelVo.setHeadFiveOn("III");
            list.add(excelVo);
        }
        return  list;
    }
}

5. Write the controller layer and call the interface

@RestController
public class alibaba {
  
    @GetMapping("/exportA")
    public void exportA(HttpServletResponse response) throws Exception {
        List<ExportExcelVo> data = ExcelService.getExportData();
        // 构建导出的map
        Map<String,String> headerMap = new LinkedHashMap<>(21);
        headerMap.put("headOne","单元格一");
        headerMap.put("headTwoCome", "单元格二");
        headerMap.put("headTwoOn", "单元格三");
        headerMap.put("headThreeCome", "单元格四");
        headerMap.put("headThreeOn", "单元格五");
        headerMap.put("headFourCome", "单元格六");
        headerMap.put("headFourOn", "单元格七");
        headerMap.put("headFiveCome", "单元格八");
        headerMap.put("headFiveOn", "单元格九");

        ExportUtil.doExport(data,headerMap,"测试.xlsx");
    }
}

6. Test export

Access in the browser address bar: http://localhost:project port number/exportA

If you need to export complex cells and merge cells, please check 

Export Excel in Java, merge cells, easy to get started_SUMMERENT's Blog-CSDN Blog