java中事务的处理

package com.test;
import java.sql.*;

class Hello
...{
    
    /** *//**
    * 该方法用以显示结果集;
    */
    private static void showResultSet( ResultSet rs ) throws Exception...{
        System.out.println("编号 图书名称 图书单价 图书数量 ");
        while(rs.next())
        ...{
                int id=rs.getInt("ID");
                String book_name=rs.getString("book_name");
                double book_price=rs.getDouble("book_price");
                int book_quantity=rs.getInt("book_quantity");
                System.out.println(id+" "+book_name+" "+book_price+" "+book_quantity);
        }
    }
    
    public static void main(String args[])
    ...{
        try
        ...{
            /** *//**
            * 将数据库中原来图书信息显示出来；
            */
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            String url="jdbc:odbc:bookdsn";         
            Connection con=DriverManager.getConnection(url,"sa","");
            Statement stmt=con.createStatement();
            ResultSet rs=stmt.executeQuery("SELECT ID,book_name,book_price,book_quantity from book_stock");
            showResultSet(rs);
            
            /** *//**
            * 下面使用事务；
            * 不必显式开启事务，在回滚或提交事务后必须将事务
            * 提交模式设置为原来默认的自动提交模式;
            */    
            con.setAutoCommit(false);
            stmt.executeUpdate("insert into book_stock (book_name,book_price,book_quantity) values ('Win2000手册',30.00,300)");
            System.out.println(" 通过execute方法插入一种新书之后:");
            System.out.println("回滚事务!");
            con.rollback();
            con.setAutoCommit(true);
            
            /** *//**
            * 再次显示数据库中图书信息;
            */
            rs=stmt.executeQuery("SELECT ID,book_name,book_price,book_quantity from book_stock");
            showResultSet(rs);    
            
            /** *//**
            * 以下断开连接;
            */
            rs.close();
            stmt.close();
            con.close();
        }
         catch(Exception e)
        ...{
            System.out.println("发生异常:"+e);
        }
    }
}