以excel方式输出数据

主类Test：

public class D201 {//get set 方法略去
    private String d201_01;
    private String d201_02;
    private String d201_03;
    private String d201_04;
    private String d201_05;

    @Override
    public String toString()
    {
        System.out.println(super.toString());
        return "abc";
    }
}

调用D201类：

import java.io.FileOutputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;

public class Test {

    private Connection connection = null;
    private PreparedStatement preparedStatement = null;
    private ResultSet resultSet = null;
    public static void main(String[] args) {
        D201 d201 = new D201();
        Test test = new Test();
        test.createExcel(test.getD201()); //调用输出数据方法

        System.out.println("********以下是验证tostring方法输出********");
        System.out.println(d201.toString());

        System.out.println(d201.getClass().getName());
        System.out.println("@");
        System.out.println(d201.hashCode());
        System.out.println(Integer.toHexString(d201.hashCode()));

    }

    //创建excel表格
    private void createExcel(List<D201> list) {

        try {
            Workbook wb = new HSSFWorkbook();
            Sheet sheet = wb.createSheet("D201");
            Row row = null;

            row = sheet.createRow(0);
            row.createCell(1, 1);
            for(int i = 0; i < list.size(); i++) {
                row = sheet.createRow(i + 1);
                D201 d201 = list.get(i);
                row.createCell(0).setCellValue(d201.getD201_01());
                row.createCell(1).setCellValue(d201.getD201_02());
                row.createCell(2).setCellValue(d201.getD201_03());
                row.createCell(3).setCellValue(d201.getD201_04());
                row.createCell(4).setCellValue(d201.getD201_05());
            }
            FileOutputStream fos = new FileOutputStream("D201.xls");
            wb.write(fos);
            fos.close();
        }catch(Exception e) {
            e.printStackTrace();
        }
    }

    private Connection getConnection()
    {
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver"); //数据库驱动‘包名+类名
            connection = DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.111:1521:orcl", "csyxzm", "csyxzm");//getConnection(String url, String user, String password) 

        } catch(Exception e) {
            e.printStackTrace();
        }
        return connection;
    }

    public List<D201> getD201()
    {
        List<D201> list = null;
        try {
            this.getConnection();
            String sql = "select t.D201_01, t.D201_02, t.D201_03, t.D201_04, t.D201_05 from D201 t";
            preparedStatement = this.connection.prepareStatement(sql);
            resultSet = preparedStatement.executeQuery();
            list = new ArrayList<D201>();
            D201 d201 = null;
            while(resultSet.next())
            {
                d201 = new D201();
                String d201_01 = resultSet.getString("D201_01");
                String d201_02 = resultSet.getString("D201_02");
                String d201_03 = resultSet.getString("D201_03");
                String d201_04 = resultSet.getString("D201_04");
                String d201_05 = resultSet.getString("D201_05");

                d201.setD201_01(d201_01);
                d201.setD201_02(d201_02);
                d201.setD201_03(d201_03);
                d201.setD201_04(d201_04);
                d201.setD201_05(d201_05);
                list.add(d201);
            }
        }catch(Exception e) {
            e.printStackTrace();
        } finally {
            this.close(connection, preparedStatement, resultSet);
        }
        return list;
    }

    private void close(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet)
    {
        try {
            if(connection != null)
            {
                connection.close();
                connection = null;
            }
            if(preparedStatement != null)
            {
                preparedStatement.close();
                preparedStatement = null;
            }

            if(resultSet != null) {
                resultSet.close();
                resultSet = null;
            }
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

}