下面是JDBC连接oracle数据库流程：
        String dbURL = "jdbc:oracle:thin:@url:1521:service_name";

        String userName = "数据库名";

        String userPwd = "密码";

        Connection con = null;

        Statement st = null;

        ResultSet rs = null;    

        try {

            Class.forName("oracle.jdbc.driver.OracleDriver");

            con = DriverManager.getConnection(dbURL, userName, userPwd);

            System.out.println("加载数据库驱动成功！");

            System.out.println("数据库连接成功！");

            st = con.createStatement();

            String sql = "select * from ETL.BD_PSNDOC";//数据库表名前面尽量加上数据库名字

            rs = st.executeQuery(sql);

            while (rs.next()) {

              .......................

             }

        }catch(Exception e){

            e.printStackTrace();

        }

        try {

            if(rs!=null){

                rs.close();

            }

            if (st != null) {

                st.close();

            }

            if (con != null) {

                con.close();

            }

        } catch (Exception e) {

            e.printStackTrace();

        }