java数据库5000万数据导出excel表格，给出示例代码

以下是一个使用Java进行大数据量导出Excel的示例代码：

import java.io.FileOutputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;

public class ExportDataToExcel {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:mysql://localhost:3306/mydatabase?useSSL=false";
        String username = "root";
        String password = "password";
        String query = "select * from mytable";
        String outputFilePath = "output.xlsx";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password);
             Statement statement = connection.createStatement();
             ResultSet resultSet = statement.executeQuery(query);
             FileOutputStream fileOutputStream = new FileOutputStream(outputFilePath)) {

            SXSSFWorkbook workbook = new SXSSFWorkbook();
            Row headerRow = workbook.createSheet().createRow(0);
            headerRow.createCell(0).setCellValue("Column1Header");
            headerRow.createCell(1).setCellValue("Column2Header");
            // Add more header cells as needed

            int rowNumber = 1;
            while (resultSet.next()) {
                Row row = workbook.getSheetAt(0).createRow(rowNumber++);
                Cell cell1 = row.createCell(0);
                cell1.setCellValue(resultSet.getString("column1"));
                Cell cell2 = row.createCell(1);
                cell2.setCellValue(resultSet.getString("column2"));
                // Add more cell values as needed
            }

            workbook.write(fileOutputStream);
            workbook.dispose();

            System.out.println("Data exported to " + outputFilePath);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

上述代码使用了Apache POI库来生成Excel文件，并使用了SXSSFWorkbook类来支持对大量数据的导出。它使用了MySQL作为示例数据库，但你可以将其替换为你实际使用的数据库。请注意，此代码仅演示了基本的导出过程，实际情况下你可能需要更复杂的查询和数据处理逻辑。