SpringBoot+EasyPOI实现百万级数据导出Excel实战指南

<!-- EasyPOI 核心库 -->
<dependency>
    <groupId>cn.afterturn</groupId>
    <artifactId>easypoi-spring-boot-starter</artifactId>
    <version>4.4.0</version>
</dependency>

<!-- Apache POI (SXSSF 需要) -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>5.2.3</version>
</dependency>

import cn.afterturn.easypoi.excel.annotation.Excel;
import cn.afterturn.easypoi.excel.entity.params.ExcelExportEntity;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;

import java.io.FileOutputStream;
import java.lang.reflect.Field;
import java.util.*;
import java.util.stream.Collectors;

public class BatchExcelExporter<T> {

    private final SXSSFWorkbook workbook;
    private final Class<T> clazz;
    private final List<ExcelExportEntity> exportEntities = new ArrayList<>();
    private int currentRowIndex = 0;

    public BatchExcelExporter(Class<T> clazz) {
        this.clazz = clazz;
        this.workbook = new SXSSFWorkbook(100); // 缓存100行到磁盘
        initHeader();
    }

    // 初始化表头（仅执行一次）
    private void initHeader() {
        // 解析实体类注解
        List<Field> fields = Arrays.stream(clazz.getDeclaredFields())
                .filter(f -> f.isAnnotationPresent(Excel.class))
                .sorted(Comparator.comparing(f -> {
                    Excel excel = f.getAnnotation(Excel.class);
                    return excel.orderNum();
                })).collect(Collectors.toList());

        // 构建导出结构
        fields.forEach(f -> {
            Excel excel = f.getAnnotation(Excel.class);
            exportEntities.add(new ExcelExportEntity(excel.name(), f.getName(), 4000));
        });

        // 创建表头
        workbook.createSheet("数据").createRow(currentRowIndex++);
        addHeaderRow(workbook.getSheetAt(0).getRow(0));
    }

    // 添加表头行
    private void addHeaderRow(org.apache.poi.ss.usermodel.Row headerRow) {
        for (int i = 0; i < exportEntities.size(); i++) {
            headerRow.createCell(i).setCellValue(exportEntities.get(i).getName());
        }
    }

    // 批量添加数据（分页调用）
    public void addBatchData(List<T> batchData) throws Exception {
        org.apache.poi.ss.usermodel.Sheet sheet = workbook.getSheetAt(0);
        for (T data : batchData) {
            org.apache.poi.ss.usermodel.Row row = sheet.createRow(currentRowIndex++);
            fillDataRow(row, data);
        }
        // 每500行刷新到磁盘（根据数据量调整）
        if (currentRowIndex % 500 == 0) {
            ((SXSSFSheet) sheet).flushRows(500);
        }
    }

    // 填充数据行（利用反射动态取值）
    private void fillDataRow(org.apache.poi.ss.usermodel.Row row, T data) throws Exception {
        for (int i = 0; i < exportEntities.size(); i++) {
            Field field = clazz.getDeclaredField((String) exportEntities.get(i).getKey());
            field.setAccessible(true);
            Object value = field.get(data);
            row.createCell(i).setCellValue(value != null ? value.toString() : "");
        }
    }

    // 最终写入文件
    public void exportToFile(String filePath) throws Exception {
        try (FileOutputStream fos = new FileOutputStream(filePath)) {
            workbook.write(fos);
        } finally {
            workbook.dispose(); // 清理临时文件
        }
    }
}

public class User {
    @Excel(name = "姓名", orderNum = "0")
    private String name;

    @Excel(name = "年龄", orderNum = "1")
    private Integer age;

    @Excel(name = "邮箱", orderNum = "2")
    private String email;

    // 省略Getter/Setter
}

public class ExcelExportDemo {
    public static void main(String[] args) throws Exception {
        // 初始化导出器（指定实体类）
        BatchExcelExporter<User> exporter = new BatchExcelExporter<>(User.class);

        // 模拟分页查询数据（假设每次查询1000条）
        for (int page = 1; page <= 10; page++) {
            List<User> batchData = queryUsersByPage(page, 1000);
            exporter.addBatchData(batchData);
        }

        // 导出到文件
        exporter.exportToFile("user_export.xlsx");
    }

    private static List<User> queryUsersByPage(int page, int size) {
        // 模拟数据库查询（此处返回测试数据）
        List<User> users = new ArrayList<>();
        for (int i = 0; i < size; i++) {
            users.add(new User("User" + i, 20 + i, "user" + i + "@example.com"));
        }
        return users;
    }
}

List<Field> fields = Arrays.stream(clazz.getDeclaredFields())
        .filter(f -> f.isAnnotationPresent(Excel.class))
        .sorted(Comparator.comparing(f -> f.getAnnotation(Excel.class).orderNum()))
        .collect(Collectors.toList());

public void addBatchData(List<T> batchData) throws Exception {
    // ... 填充数据 ...
    if (currentRowIndex % 500 == 0) {
        ((SXSSFSheet) sheet).flushRows(500);  // 🚨 关键性能优化点！
    }
}