Spring Boot项目基于POI框架导出Excel表格

1.    依赖

     我的项目是基于Spring Boot的，这里只贴出POI框架需要依赖的两个包，其他的都无所谓，只要能提供Controller让浏览器访问即可。在pom.xml配置文件中增加如下两个包：

       <!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>4.1.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi-ooxml</artifactId>
            <version>4.1.2</version>
        </dependency>

2. 代码实现

package com.eg.wiener.controller;

import com.eg.wiener.dto.User;
import com.eg.wiener.utils.ExcelUtils;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.BorderStyle;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.ss.usermodel.HorizontalAlignment;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.stream.Stream;

/**
 * @author Wiener
 * @date 2020/9/5
 */
@Slf4j
@RestController
@RequestMapping("/excel")
public class ExcelExportController {

    private static HSSFWorkbook workbook = null;
    // 代表一行记录
    private static HSSFCell cell = null;
    private static HSSFRow row = null;

    @RequestMapping(value = "/exportExcel")
    public Object exportExcel(HttpServletRequest request, HttpServletResponse response) throws Exception {
        String fileSuffix = ".xls";
        String fileName = "导出数据至Excel示例"+ "_" + (int) (Math.random() * 9000 + 1000) + ".xls";

        //【1】创建excel
        workbook = new HSSFWorkbook();
        // 设置表头的类型
        HSSFCellStyle style = setCellStyle(workbook);

        // 创建一个sheet
        HSSFSheet sheet = workbook.createSheet("sheet1");

        try {
            List<User> dataList = getUsers();

            if (CollectionUtils.isNotEmpty(dataList)) {
                //【2】 设置表头：对Excel每列命名
                String[] tableHeader = Stream.of("编号", "姓名", "年龄").toArray(String[]::new);
                // 设置Excel表头
                row = ExcelUtils.getExcelRow(workbook, sheet, tableHeader);
                //通过反射，获取POJO对象。由于同一个dataList中，POJO相同，故定义在for循环外部，提高遍历性能
                Class cl = dataList.get(0).getClass();
                //获取类的所有字段
                Field[] fields = cl.getDeclaredFields();
                //写入每一行的记录
                for (int i = 0; i < dataList.size(); i++) {
                    //创建新的一行，递增
                    row = sheet.createRow(i + 1);
                    // 设置行高
                    row.setHeight((short) 400);
                    for (int j = 0; j < fields.length; j++) {
                        //设置字段可见，否则会报错，禁止访问
                        fields[j].setAccessible(true);
                        //创建单元格
                        cell = row.createCell(j);
                        cell.setCellValue(Objects.toString(fields[j].get(dataList.get(i)), ""));
                        cell.setCellStyle(style);
                    }
                }
            } else {
                // 没有查到数据提示行
                row = ExcelUtils.getNotResultInfoRow(workbook, sheet, "记录为空");
            }
        } catch (Exception e) {
            log.error("导出数据失败：", e);
            // 写入Excel失败原因
            row = ExcelUtils.getNotResultInfoRow(workbook, sheet, "导出数据失败");
            fileName = "导出数据失败";
        }
        fileName = fileName + "_" + (int) (Math.random() * 9000 + 1000) + fileSuffix;

        //下载文件
        ExcelUtils.outputExcelStream(request, response, workbook, fileName);

        return "导出成功";
    }

    private List<User> getUsers() {
        List<User> list = new ArrayList<>();
        User aUser = new User();
        aUser.setAge(18);
        aUser.setId(1);
        aUser.setName("Tony");
        list.add(aUser);

        aUser = new User();
        aUser.setAge(21);
        aUser.setId(2);
        aUser.setName("Tom");
        list.add(aUser);
        aUser = new User();
        aUser.setAge(20);
        aUser.setId(3);
        aUser.setName("店小二");
        list.add(aUser);
        return list;
    }

    private HSSFCellStyle setCellStyle(HSSFWorkbook myWorkbook) {
        HSSFCellStyle style = myWorkbook.createCellStyle();
        //设置自动换行
        style.setWrapText(true);
        style.setAlignment(HorizontalAlignment.CENTER);
        //设置边框样式
        style.setBorderTop(BorderStyle.THIN);
        style.setBorderBottom(BorderStyle.THIN);
        style.setBorderLeft(BorderStyle.THIN);
        style.setBorderRight(BorderStyle.THIN);
        //设置边框颜色
        style.setTopBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());
        style.setBottomBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());
        style.setLeftBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());
        style.setRightBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());

        HSSFDataFormat format = workbook.createDataFormat();
        // 设置文本格式
        style.setDataFormat(format.getFormat("@"));
        // 设置字体
        HSSFFont font = workbook.createFont();
        font.setColor(Font.COLOR_RED);
        font.setFontName("宋体");
        font.setFontHeightInPoints((short) 12);// 12号字体
        style.setFont(font);
        return style;
    }
}

    通过反射获取POJO对象，故传入不同类型的POJO对象的dataList就可以了。下面是依赖的一个工具类：

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.BorderStyle;
import org.apache.poi.ss.usermodel.HorizontalAlignment;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URLEncoder;

/**
 * 导出Excel工具类
 *
 * @author Wiener
 * @date 2020/9/5
 */
@Slf4j
public class ExcelUtils {

    /**
     * 设置Excel表头
     *
     * @param workbook
     * @param sheet
     * @param tableHeader
     * @return
     */
    public static HSSFRow getExcelRow(HSSFWorkbook workbook, HSSFSheet sheet, String[] tableHeader) {
        short cellNumber = (short) tableHeader.length;
        // Excel的第一行表头
        HSSFRow row = sheet.createRow(0);
        // 设置行高
        row.setHeight((short) 560);
        // Excel的列
        HSSFCell cell = null;
        HSSFFont font = workbook.createFont();
        // 粗体显示
        font.setBold(Boolean.TRUE);
        font.setFontHeightInPoints((short) 15);
        // 设置单元格字体的颜色
        font.setColor(HSSFFont.COLOR_NORMAL);
        // 样式
        HSSFCellStyle style = workbook.createCellStyle();
        style.setAlignment(HorizontalAlignment.CENTER);
        //设置边框样式
        style.setBorderTop(BorderStyle.DOTTED);
        style.setBorderBottom(BorderStyle.DOTTED);
        style.setBorderLeft(BorderStyle.DOTTED);
        style.setBorderRight(BorderStyle.DOTTED);
        //设置边框颜色
        style.setTopBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());
        style.setBottomBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());
        style.setLeftBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());
        style.setRightBorderColor(HSSFColor.HSSFColorPredefined.BLACK.getIndex());

        for (int k = 0; k < cellNumber; k++) {
            int i = 0;
            i += k;
            short b = 6000;
            cell = row.createCell(i);                       // 创建第0行第k列
            cell.setCellValue(tableHeader[k]);              // 设置第0行第k列的值
            sheet.setColumnWidth(i, b);                     // 设置列的宽度
            style.setFont(font);                           // 设置字体风格
            cell.setCellStyle(style);
        }
        return row;
    }

    /**
     * 设置Excel未获取数据提示行
     *
     * @param workbook
     * @param sheet
     * @return
     */
    public static HSSFRow getNotResultInfoRow(HSSFWorkbook workbook, HSSFSheet sheet, String message) {
        // Excel的第一行表头
        HSSFRow row = sheet.createRow(0);
        // Excel的列
        HSSFCell cell = null;
        // 设置表头的类型
        HSSFCellStyle style = workbook.createCellStyle();
        //设置自动换行
        style.setWrapText(true);
        style.setAlignment(HorizontalAlignment.CENTER);

        // 没有查到数据
        row = sheet.createRow((short) (0));             // 创建第j+1行
        row.setHeight((short) 1000);                    // 设置行高
        sheet.setColumnWidth(0, 10000);
        cell = row.createCell(0);                       // 创建第i+1行第1列
        cell.setCellValue(message);//
        cell.setCellStyle(style);                       // 设置风格

        return row;
    }

    /**
     * 下载EXCEL,对不同浏览器做中文名称兼容<br/>
     * 如果不对文件名进行编码处理，那么有些浏览器无法识别下载文件
     *
     * @param request
     * @param response
     * @param workbook
     * @param fileName
     */
    public static void outputExcelStream(HttpServletRequest request, HttpServletResponse response, HSSFWorkbook workbook, String fileName) {
        OutputStream out = null;
        try {
            String excelFileName = fileName + "_" + (int) (Math.random() * 9000 + 1000) + ".xls";
            if (isMsBrowser(request)) {
                // ie,edge 浏览器
                excelFileName = URLEncoder.encode(excelFileName, "UTF-8");
            } else {
                //其他的浏览器
                excelFileName = new String(excelFileName.getBytes("UTF-8"), "iso-8859-1");
            }
            //输出流对象
            out = response.getOutputStream();
            // 设置文件头编码方式和文件名
            response.setHeader("Content-Disposition", "attachment;filename=" + excelFileName);
            // 设置类型
            response.setContentType("application/msexcel;charset=UTF-8");
            response.setHeader("Pragma", "No-cache");
            response.setHeader("Cache-Control", "no-cache");
            response.setDateHeader("Expires", 0);
            workbook.write(out);
            out.flush();
            workbook.write(out);
        } catch (IOException e) {
            log.error("下载EXCEL失败，", e);
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
            } catch (IOException e) {
                log.error("下载EXCEL关闭文件流失败，", e);
            }
        }
    }

    //判断是否是IE浏览器
    private static boolean isMsBrowser(HttpServletRequest request) {
        String userAgent = request.getHeader("User-Agent");
        if (StringUtils.isBlank(userAgent)) {
            return false;
        }
        String[] IEBrowserSignals = {"msie", "trident", "edge"};
        for (String signal : IEBrowserSignals) {
            if (userAgent.toLowerCase().contains(signal)) {
                return true;
            }
        }
        return false;
    }

}

      在使用的时候，仅仅需要传入不同的表头集合、实体类集合，就能实现需求，这就是封装的魅力所在。