java导出百万数据到excel

以下是Java导出百万数据到Excel的示例代码：

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

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;

public class ExcelExporter {
    private static final int ROW_ACCESS_WINDOW_SIZE = 100;

    private List<String[]> data;

    public ExcelExporter() {
        data = new ArrayList<>();
        // 添加百万条数据到列表中
        for (int i = 1; i <= 1000000; i++) {
            String[] row = { "数据" + i, "数据" + i, "数据" + i };
            data.add(row);
        }
    }

    public void export(String fileName) throws IOException {
        Workbook workbook = new SXSSFWorkbook(ROW_ACCESS_WINDOW_SIZE);
        Sheet sheet = workbook.createSheet("Sheet1");

        int rowIndex = 0;
        for (String[] rowData : data) {
            Row row = sheet.createRow(rowIndex++);
            int cellIndex = 0;
            for (String cellData : rowData) {
                Cell cell = row.createCell(cellIndex++);
                cell.setCellValue(cellData);
            }
        }

        FileOutputStream outputStream = new FileOutputStream(fileName);
        workbook.write(outputStream);
        outputStream.close();
        workbook.close();
    }
}

使用示例：

public class Example {
    public static void main(String[] args) {
        ExcelExporter exporter = new ExcelExporter();
        try {
            exporter.export("data.xlsx");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

该示例使用Apache POI库创建一个XLSX格式的Excel文件，使用SXSSFWorkbook类可以将数据写入到Excel中，并且使用分页窗口技术来提高性能，避免内存溢出。