使用EasyPoi实现百万级数据导出的性能优化方案

// 在导出工具类中设置
Workbook workbook = new SXSSFWorkbook(100); // 保留100行在内存
Sheet sheet = workbook.createSheet("大数据报表");

public class BigDataExporter implements IExcelExportServer {
    @Override
    public List<Object> selectListForExcelExport(Object queryParams, int pageNo) {
        // 分页查询逻辑
        PageHelper.startPage(pageNo, 50000);
        return dataMapper.selectByCondition(queryParams);
    }
}

@Async
public CompletableFuture<String> asyncExport() {
    // 生成临时文件
    File tempFile = File.createTempFile("export_", ".xlsx");
    Workbook workbook = ExcelExportUtil.exportBigExcel(...);
    FileOutputStream fos = new FileOutputStream(tempFile);
    workbook.write(fos);
    fos.close();
    return CompletableFuture.completedFuture(tempFile.getAbsolutePath());
}

# 内存配置
-Xms4g -Xmx8g -XX:MaxMetaspaceSize=512m
# GC策略
-XX:+UseG1GC -XX:MaxGCPauseMillis=200

# 导出配置
easypoi.export.buffer-size=1048576  # 1MB缓冲区
easypoi.export.compressed=true      # 启用压缩
easypoi.export.auto-flush=true      # 自动刷新缓冲区

@GetMapping("/export")
public void exportBigData(HttpServletResponse response) {
    ExportParams params = new ExportParams();
    params.setType(ExcelType.XSSF);  // 或 SXSSF
    params.setStyle(ExcelExportStylerImpl.class);  // 自定义样式
    
    IExcelExportServer server = new BigDataExporter();
    Workbook workbook = ExcelExportUtil.exportBigExcel(params, DataEntity.class, server, queryParams);
    
    response.setHeader("Content-Disposition", "attachment;filename=report.xlsx");
    workbook.write(response.getOutputStream());
    ((SXSSFWorkbook) workbook).dispose();  // 清理临时文件
}

public class MultiSheetExporter {
    public Workbook export(List<PageData> dataPages) {
        Workbook workbook = new SXSSFWorkbook();
        int sheetCount = dataPages.size();
        
        for (int i=0; i<sheetCount; i++) {
            Sheet sheet = workbook.createSheet("Sheet" + (i+1));
            List<DataEntity> pageData = dataPages.get(i);
            // 写入表头
            Row header = sheet.createRow(0);
            // 写入数据
            int rowNum = 1;
            for (DataEntity entity : pageData) {
                Row row = sheet.createRow(rowNum++);
                // 填充单元格
            }
        }
        return workbook;
    }
}

FileChannel channel = new RandomAccessFile("temp.xlsx", "rw").getChannel();
MappedByteBuffer buffer = channel.map(FileChannel.MapMode.READ_WRITE, 0, 1024 * 1024 * 100);

response.setHeader("Content-Length", String.valueOf(file.length()));
FileChannel fileChannel = new FileInputStream(file).getChannel();
WritableByteChannel outChannel = Channels.newChannel(response.getOutputStream());
fileChannel.transferTo(0, fileChannel.size(), outChannel);