12c在搭建em express时，步骤非常的简单，摆脱了11g时臃肿的局面。只需一步即可。例如： (1) Use the PL/SQL procedure DBMS_XDB_CONFIG.SETHTTPSPORT to set the HTTPS port for EM Express. This will update the HTTPS port in the Oracle XML DB Repository. You must connect as SYS / AS SYSDBA to run the procedure.
SQL> connect sys/<password>@<container> as sysdba
SQL> exec DBMS_XDB_CONFIG.SETHTTPSPORT(5500);
访问em地址为：https://hostname:5500/em
(2) Use the PL/SQL procedure DBMS_XDB_CONFIG.SETHTTPPORT to set the HTTP port for EM Express. This will update the HTTP port in the Oracle XML DB Repository.
SQL> connect sys/<password>@<container> as sysdba
SQL> exec DBMS_XDB_CONFIG.SETHTTPPORT(5500);
访问em地址为： http://hostname:5500/em 若想取消EM配置，则执行：
SQL> connect sys/<password>@<container> as sysdba
SQL> exec DBMS_XDB_CONFIG.SETHTTPSPORT(0);或
SQL> connect sys/<password>@<container> as sysdba
SQL> exec DBMS_XDB_CONFIG.SETHTTPPORT(0);
参考文档：官网文档(Doc ID 1604062.1) https://www.eygle.com/archives/2013/07/oracle_database_12c_em_express.html
