将数据库中的数据表导出Excel

代码：

package com.XXX.controller;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.sql.*;

/**
 * @author XXXX
 * @date XXXX/XX/XX
 */
public class MySQLDownLoadExcel {
    /**
     * 将数据库中的数据表写入Excel表格
     */
    public static void main(String[] args) {
        String dname = "command_document";//数据库名称
        String tname = "command_list";//要导出的表名
        String path = "C:/Users/dell/Desktop/"+tname+".xls";//导出位置
        HSSFWorkbook book = new HSSFWorkbook();//创建一个Excel文件
        HSSFSheet sheet = book.createSheet("表");
        try {
            //连接数据库
            Class.forName("com.mysql.cj.jdbc.Driver");
            Connection connection;
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/"+dname+"?useUnicode=true&characterEncoding=utf-8","root","root");
            Statement statement = connection.createStatement();
            //写查询的sql语句，查出想要导出的表内容
            String sql = "select * from "+tname;
            //执行sql
            ResultSet rs = statement.executeQuery(sql);
            ResultSetMetaData rsmd = rs.getMetaData(); //得到结果集的字段名
            int a = rsmd.getColumnCount();//得到数据表的结果集的字段的数量
            //生成表单的第一行，即表头
            HSSFRow row0 = sheet.createRow(0);//创建第一行
            for (int i = 0; i < a; i++) {
                HSSFCell cell = row0.createCell(i);//创建第一行的第i列
                cell.setCellValue(rsmd.getColumnName(i+1));
            }
            //将数据表中的数据按行导入进Excel表中
            int r = 1;
            while(rs.next()){
                HSSFRow row = sheet.createRow(r++);//创建非第一行的其他行
                for (int i = 0; i < c; i++) {//仍然是c列，导入第r行的第i列
                    HSSFCell cel = row.createCell(i);
                    cel.setCellValue(rs.getString(i+1));
                }
            }
            //用文件输出流创建表格
            try {
                FileOutputStream outputStream = new FileOutputStream(path);
                try {
                    book.write(outputStream);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                try {
                    book.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }catch (SQLException throwables) {
            throwables.printStackTrace();
        }
    }
}