java 多线程千万级数据导出

以下是Java多线程千万级数据导出的示例代码：

import java.io.File;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.metadata.Sheet;
import com.alibaba.excel.support.ExcelTypeEnum;

public class ExcelExportUtil {

    /**
     * 导出Excel
     * 
     * @param dataList 数据列表
     * @param sheetName sheet名称
     * @param filePath 文件路径
     * @param fileName 文件名
     * @param sheetSize 每个sheet中数据的行数
     */
    public static void exportExcel(List<List<Object>> dataList, String sheetName, String filePath, String fileName,
            int sheetSize) {
        // 创建线程池
        ExecutorService executorService = Executors.newFixedThreadPool(10);
        // 创建ExcelWriter
        ExcelWriter excelWriter = new ExcelWriter(new File(filePath + fileName), ExcelTypeEnum.XLSX);
        // 计算需要创建的sheet数量
        int sheetCount = dataList.size() % sheetSize == 0 ? dataList.size() / sheetSize : dataList.size() / sheetSize + 1;
        // 创建计数器
        CountDownLatch countDownLatch = new CountDownLatch(sheetCount);
        // 创建sheet
        for (int i = 0; i < sheetCount; i++) {
            // 计算每个sheet中数据的起始位置和结束位置
            int startIndex = i * sheetSize;
            int endIndex = Math.min(startIndex + sheetSize, dataList.size());
            // 创建sheet
            Sheet sheet = new Sheet(i + 1, 0);
            sheet.setSheetName(sheetName + (i + 1));
            // 创建数据列表
            List<List<Object>> sheetDataList = new ArrayList<>();
            for (int j = startIndex; j < endIndex; j++) {
                sheetDataList.add(dataList.get(j));
            }
            // 将sheet数据提交到线程池中进行处理
            executorService.submit(new ExcelExportTask(excelWriter, sheet, sheetDataList, countDownLatch));
        }
        try {
            // 等待所有线程处理完成
            countDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            // 关闭ExcelWriter和线程池
            excelWriter.finish();
            executorService.shutdown();
        }
    }

}

其中，ExcelExportTask是一个实现了Runnable接口的任务类，用于将数据写入Excel中。具体代码如下：

import java.util.List;
import java.util.concurrent.CountDownLatch;

import com.alibaba.excel.ExcelWriter;
import com.alibaba.excel.metadata.Sheet;

public class ExcelExportTask implements Runnable {

    private ExcelWriter excelWriter;
    private Sheet sheet;
    private List<List<Object>> dataList;
    private CountDownLatch countDownLatch;

    public ExcelExportTask(ExcelWriter excelWriter, Sheet sheet, List<List<Object>> dataList,
            CountDownLatch countDownLatch) {
        this.excelWriter = excelWriter;
        this.sheet = sheet;
        this.dataList = dataList;
        this.countDownLatch = countDownLatch;
    }

    @Override
    public void run() {
        try {
            // 写入数据
            excelWriter.write0(dataList, sheet);
        } finally {
            // 计数器减1
            countDownLatch.countDown();
        }
    }

}

使用示例：

import java.util.ArrayList;
import java.util.List;

public class ExcelExportTest {

    public static void main(String[] args) {
        // 模拟数据
        List<List<Object>> dataList = new ArrayList<>();
        for (int i = 0; i < 10000000; i++) {
            List<Object> row = new ArrayList<>();
            row.add("数据" + i);
            dataList.add(row);
        }
        // 导出Excel
        ExcelExportUtil.exportExcel(dataList, "Sheet1", "D:/", "data.xlsx", 1000000);
    }

}