SpringBoot导出Excel的最佳实践

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import javax.servlet.http.HttpServletResponse;
import java.net.URLEncoder;
import java.util.List;
import java.util.function.Function;
/**
 * 通用 Excel 导出工具类
 */
public class ExcelExportUtil {
    /**
     * 核心导出方法
     * @param response   HttpServletResponse
     * @param fileName   文件名
     * @param title      表格大标题（传空则不生成）
     * @param headers    表头集合
     * @param dataList   数据集合 List<T>
     * @param extractors 数据提取规则集合，支持动态翻译和格式化
     */
    public static <T> void export(HttpServletResponse response, 
                                  String fileName, 
                                  String title, 
                                  List<String> headers, 
                                  List<T> dataList, 
                                  List<Function<T, Object>> extractors) throws Exception {
        if (headers.size() != extractors.size()) {
            throw new IllegalArgumentException("表头列数与数据提取规则数量不一致！");
        }
        // 使用 SXSSFWorkbook 防 OOM，内存仅保留 100 行
        SXSSFWorkbook workbook = new SXSSFWorkbook(100);
        Sheet sheet = workbook.createSheet("Sheet1");
        int rowIndex = 0;
        // 1. 生成大标题 (可选)
        if (title != null && !title.isEmpty()) {
            Row titleRow = sheet.createRow(rowIndex++);
            Cell titleCell = titleRow.createCell(0);
            titleCell.setCellValue(title);
            sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, headers.size() - 1));
        }
        // 2. 生成表头
        Row headerRow = sheet.createRow(rowIndex++);
        for (int i = 0; i < headers.size(); i++) {
            Cell cell = headerRow.createCell(i);
            cell.setCellValue(headers.get(i));
            sheet.setColumnWidth(i, 15 * 256); // 简单统一列宽
        }
        // 3. 填充数据（核心亮点：使用 Function 动态取值并转换）
        for (T data : dataList) {
            Row row = sheet.createRow(rowIndex++);
            for (int i = 0; i < extractors.size(); i++) {
                Cell cell = row.createCell(i);
                // 执行外部传入的 Lambda 表达式
                Object value = extractors.get(i).apply(data);
                if (value != null) {
                    if (value instanceof Number) {
                        cell.setCellValue(((Number) value).doubleValue());
                    } else {
                        cell.setCellValue(value.toString());
                    }
                } else {
                    cell.setCellValue("");
                }
            }
        }
        // 4. 写出响应流
        response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        String encodedFileName = URLEncoder.encode(fileName, "UTF-8").replaceAll("\\+", "%20");
        response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + encodedFileName + ".xlsx");
        try {
            workbook.write(response.getOutputStream());
        } finally {
            workbook.dispose(); // 清理磁盘临时文件
            workbook.close();
        }
    }
}

@PostMapping("/exportFinanceRecord")
public void exportFinanceRecord(HttpServletResponse response, @RequestBody FinanceQuery param) throws Exception {
    List<FinanceRecord> recordList = financeRecordService.list(param);
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    // 定义表头
    List<String> headers = Arrays.asList("记录ID", "收支类型", "金额", "创建时间");

    // 定义数据提取与转换规则（利用 Lambda 表达式）
    List<Function<FinanceRecord, Object>> extractors = Arrays.asList(
        FinanceRecord::getId, 
        record -> record.getType() == 1 ? "收入" : "支出", // 完美解决字典翻译
        FinanceRecord::getAmount,
        record -> record.getCreateTime() != null ? sdf.format(record.getCreateTime()) : "" // 日期安全格式化
    );

    // 一行代码调用导出
    ExcelExportUtil.export(response, "财务收支记录表", "财务明细大表", headers, recordList, extractors);
}

import com.alibaba.excel.annotation.ExcelProperty;
import com.alibaba.excel.annotation.format.DateTimeFormat;
import com.alibaba.excel.annotation.write.style.ColumnWidth;
import lombok.Data;
import java.util.Date;

@Data
public class FinanceRecordExportVO {

    @ExcelProperty("记录ID")
    @ColumnWidth(12)
    private Integer id;

    // 翻译逻辑可以在 Service 层查询后处理，或者实现 EasyExcel 的 Converter
    @ExcelProperty("收支类型")
    @ColumnWidth(12)
    private String typeStr; 

    @ExcelProperty("金额")
    @ColumnWidth(15)
    private Double amount;

    @ExcelProperty("创建时间")
    @ColumnWidth(22)
    @DateTimeFormat("yyyy-MM-dd HH:mm:ss") // 自带强大的格式化注解
    private Date createTime;
}

@PostMapping("/exportFinanceRecord")
public void exportFinanceRecord(HttpServletResponse response, @RequestBody FinanceQuery param) throws Exception {
    // 1. 查询数据并转换为 VO 集合 (推荐使用 MapStruct 等工具)
    List<FinanceRecordExportVO> voList = getAndConvertData(param);

    // 2. 设置响应头
    response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
    response.setCharacterEncoding("utf-8");
    String fileName = URLEncoder.encode("财务收支记录", "UTF-8");
    response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");

    // 3. 一行代码完成写入！
    EasyExcel.write(response.getOutputStream(), FinanceRecordExportVO.class)
             .sheet("数据明细")
             .doWrite(voList);
}

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>easyexcel</artifactId>
    <version>3.3.4</version> </dependency>