java链接oracle

package cracle;      
import java.sql.Connection;      
import java.sql.DriverManager;      
import java.sql.ResultSet;      
import java.sql.Statement;      
public class Oracle      
{      
    public static void main(String[] args) throws Exception      
    {      
        Class.forName("oracle.jdbc.driver.OracleDriver");      
        Connection connection= DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:byqiuxi","tt","tt");<br>//本机，服务名，用户，密码 

//这个是插入的    
PreparedStatement ps=connection.prepareStatement(" insert into buy values(?,?,?)");      
     
ps.setString(1, "2");      
ps.setString(2, "dd");      
ps.setString(3, "ddd");      
 ps.executeUpdate(); 

//这个是查询的    
Statement st= connection.createStatement();      
    ResultSet rs= st.executeQuery("select * from buy");      
        while(rs.next())      
        {      
            System.out.println("33333");      
            System.out.println(rs.getString(1));      
            System.out.println(rs.getString(2));      
            System.out.println(rs.getString(3));      
          
        }      
              
              
    }      
     
}