JDBC初步（一）

import java.sql.*;

public class TestJDBC {
    // orcl为oracle数据库中的数据库名，localhost表示连接本机的oracle数据库
    // 1521为连接的端口号
    private static String url = "jdbc:oracle:thin:@localhost:1521:ORCL";
    // scott为登陆oracle数据库的用户名
    private static String user = "scott";
    // tiger为用户名scott的密码
    private static String password = "tiger"; 

   public static void main(String[] args) throws Exception {

        Connection conn = null ;
        Statement stm = null;
        ResultSet rs = null;
        try {
            //1、注册：方法一
            Class.forName("oracle.jdbc.driver.OracleDriver");

            /*
            //注册：方法二
            new oracle.jdbc.driver.OracleDriver();
            */

            //2、连接
            conn = DriverManager.getConnection(url,user,password);
            if (conn == null) {
                System.out.println("connect fail with Oracle！");
            } else {
                System.out.println("connect success with Oracle！");
            }

            //3.将数据发送到数据库中
            stm = conn.createStatement();

            //4.执行语句
            rs = stm.executeQuery("select * from emp;");

            //5.显示语句
            while (rs.next()) {
                System.out.println(rs.getString("ename"));
            }
        } catch (ClassNotFoundException e) {
            //将异常信息打印到日志中
            e.printStackTrace();

        }finally{
            try {
                if (rs != null) {
                    rs.close();
                    rs = null;//确保垃圾回收器可以及时回收已不再使用的实例对象
                }
                if (stm != null) {
                    stm.close();
                    stm = null;//同上
                }
                if (conn != null) {
                    conn.close();
                    conn = null;//同上
                }
            } catch (SQLException e) {
                //将异常信息打印到log中
                e.printStackTrace();
            }
        }
    }

}