itext poi 学习之旅 （3）读取数据库信息并由excel展现出来

package com.zkbj.poi;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DBConnection {
    private final String DBUrl = "jdbc:mysql://localhost:3306/****";   //1.修改数据库名
    private final String DBDriver = "com.mysql.jdbc.Driver";
    private final String username = "**"; 　　　　　　　　　　　　　　　　　　//2.修改成你的MySql登录名和密码
    private final String password = "***";
    private Connection con;

    public DBConnection() {
        try {
            Class.forName(DBDriver);
            con = DriverManager.getConnection(DBUrl, username, password);
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public Connection getDB() {
        return con;
    }

    public void closeDb(ResultSet rs, PreparedStatement ps) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block

                e.printStackTrace();
            }
        }
        if (ps != null) {
            try {
                ps.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

package com.zkbj.poi;

import java.io.FileOutputStream;
import java.io.OutputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFRichTextString;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;

public class ProductDirExcel {
    public ProductDirExcel() throws Exception {
        Connection con = null;
        DBConnection db = new DBConnection();
        con = db.getDB();
        String sql = "select * from productdir";
        ResultSet rs = con.createStatement().executeQuery(sql);
        // 获取总列数
        int CountColumnNum = rs.getMetaData().getColumnCount();
        int i = 1;
        // 创建Excel文档
        HSSFWorkbook wb = new HSSFWorkbook();
        // sheet 对应一个工作页
        HSSFSheet sheet = wb.createSheet("productdir表中的数据");  //3.修改成你的Sheet
        HSSFRow firstrow = sheet.createRow(0); // 下标为0的行开始
        HSSFCell[] firstcell = new HSSFCell[CountColumnNum];
        String[] names = new String[CountColumnNum];
        names[0] = "产品ID";                                     //4.修改成你的数据库数据名称。
        names[1] = "产品名称";
        names[2] = "产品版本";
        names[3] = "产品备注";
        names[4] = "产品分类ID";

        for (int j = 0; j < CountColumnNum; j++) {
            firstcell[j] = firstrow.createCell((short) j);
            firstcell[j].setCellValue(new HSSFRichTextString(names[j]));
        }
        while (rs.next()) {
            // 创建电子表格的一行
            HSSFRow row = sheet.createRow(i); // 下标为1的行开始
            for (int j = 0; j < CountColumnNum; j++) {
                // 在一行内循环
                HSSFCell cell = row.createCell((short) j);
                // 设置表格的编码集，使支持中文
                // // 先判断数据库中的数据类型
                // 将结果集里的值放入电子表格中
                cell.setCellValue(new HSSFRichTextString(rs.getString(j + 1)));
            }
            i++;
        }
        // 创建文件输出流，准备输出电子表格
        OutputStream out = new FileOutputStream("D:\\productdir.xls");            //5.修改成你创建Excel路径 并有这个文件展示数据
        wb.write(out);
        out.close();
        System.out.println("数据库导出成功");
        rs.close();
        con.close();
    }

    public static void main(String[] args) {
        try {
            @SuppressWarnings("unused")
            ProductDirExcel excel = new ProductDirExcel();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}