Java EasyExcel导出报内存溢出的解决办法

     String fileName = "large_data.xlsx";
     ExcelWriter excelWriter = EasyExcel.write(fileName).build();
     WriteSheet writeSheet = EasyExcel.writerSheet("Sheet1").build();

     // 假设每次写入10000条数据
     int batchSize = 10000;
     List<Data> dataList;
     int pageIndex = 0;
     do {
         // 分页获取数据
         dataList = getDataByPage(pageIndex++, batchSize);
         excelWriter.write(dataList, writeSheet);
     } while (dataList.size() == batchSize);

     // 关闭资源
     excelWriter.finish();

java -Xms512M -Xmx4G -jar yourApp.jar

     EasyExcel.write(fileName)
             .registerWriteHandler(new SimpleWriteHandler()) // 不使用自动列宽
             .sheet("Sheet1")
             .doWrite(dataList);

     try (OutputStream out = new BufferedOutputStream(new FileOutputStream(fileName))) {
         ExcelWriter excelWriter = EasyExcel.write(out).build();
         WriteSheet writeSheet = EasyExcel.writerSheet("Sheet1").build();
         int pageIndex = 0;
         List<Data> dataList;
         do {
             dataList = getDataByPage(pageIndex++, batchSize);
             excelWriter.write(dataList, writeSheet);
         } while (dataList.size() == batchSize);
         excelWriter.finish();
     } catch (IOException e) {
         e.printStackTrace();
     }

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class LargeDataExportExample {

    public static void main(String[] args) {
        // 文件输出路径
        String filePath = "vg_large_data_export.xlsx";
        
        // 导出百万级数据
        exportLargeData(filePath);
    }

    private static void exportLargeData(String filePath) {
        // 每次写入的批次大小
        final int batchSize = 10000;
        // 数据总条数
        final int totalRows = 1_000_000;

        // 创建SXSSFWorkbook对象，内存中只保留100行，超过的部分会写入临时文件
        SXSSFWorkbook workbook = new SXSSFWorkbook(100);
        workbook.setCompressTempFiles(true); // 启用临时文件压缩

        // 创建工作表
        Sheet sheet = workbook.createSheet("Large Data");

        // 创建标题行
        Row headerRow = sheet.createRow(0);
        String[] headers = {"ID", "Name", "Age"};
        for (int i = 0; i < headers.length; i++) {
            Cell cell = headerRow.createCell(i);
            cell.setCellValue(headers[i]);
        }

        int rowNum = 1; // 数据开始的行号

        try {
            // 按批次写入数据
            for (int i = 0; i < totalRows / batchSize; i++) {
                // 模拟获取每批数据
                List<Data> dataList = getDataBatch(rowNum, batchSize);
                
                // 将数据写入到Excel中
                for (Data data : dataList) {
                    Row row = sheet.createRow(rowNum++);
                    row.createCell(0).setCellValue(data.getId());
                    row.createCell(1).setCellValue(data.getName());
                    row.createCell(2).setCellValue(data.getAge());
                }

                // 处理完成一批数据后，可以选择清除缓存数据，防止内存溢出
                ((SXSSFSheet) sheet).flushRows(batchSize); // 清除已写的行缓存
            }

            // 将数据写入文件
            try (FileOutputStream fos = new FileOutputStream(filePath)) {
                workbook.write(fos);
            }
            System.out.println("数据导出完成：" + filePath);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭workbook并删除临时文件
            workbook.dispose();
        }
    }

    /**
     * 模拟分页获取数据
     */
    private static List<Data> getDataBatch(int startId, int batchSize) {
        List<Data> dataList = new ArrayList<>(batchSize);
        for (int i = 0; i < batchSize; i++) {
            dataList.add(new Data(startId + i, "Name" + (startId + i), 20 + (startId + i) % 50));
        }
        return dataList;
    }

    // 数据类
    static class Data {
        private final int id;
        private final String name;
        private final int age;

        public Data(int id, String name, int age) {
            this.id = id;
            this.name = name;
            this.age = age;
        }

        public int getId() {
            return id;
        }

        public String getName() {
            return name;
        }

        public int getAge() {
            return age;
        }
    }
}