JDBC初步（一）

import java.sql.*;

public class TestJDBC {
    // orcl為oracle資料庫中的資料庫名，localhost表示連接本機的oracle資料庫
    // 1521為連接的埠號
    private static String url = "jdbc:oracle:thin:@localhost:1521:ORCL";
    // scott為登陸oracle資料庫的用戶名
    private static String user = "scott";
    // tiger為用戶名scott的密碼
    private static String password = "tiger"; 

   public static void main(String[] args) throws Exception {
        
        Connection conn = null ;
        Statement stm = null;
        ResultSet rs = null;
        try {
            //1、註冊：方法一
            Class.forName("oracle.jdbc.driver.OracleDriver");
            
            /*
            //註冊：方法二
            new oracle.jdbc.driver.OracleDriver();
            */
            
            //2、連接
            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.將數據發送到資料庫中
            stm = conn.createStatement();
            
            //4.執行語句
            rs = stm.executeQuery("select * from emp;");
            
            //5.顯示語句
            while (rs.next()) {
                System.out.println(rs.getString("ename"));
            }
        } catch (ClassNotFoundException e) {
            //將異常信息列印到日誌中
            e.printStackTrace();
            
        }finally{
            try {
                if (rs != null) {
                    rs.close();
                    rs = null;//確保垃圾回收器可以及時回收已不再使用的實例對象
                }
                if (stm != null) {
                    stm.close();
                    stm = null;//同上
                }
                if (conn != null) {
                    conn.close();
                    conn = null;//同上
                }
            } catch (SQLException e) {
                //將異常信息列印到log中
                e.printStackTrace();
            }
        }
    }

}