DBCA时没有安装EM express
后来安装就一个命令
exec dbms_xdb_config.sethttpport(5000);
http://192.168.1.11:5000/em
切换到PDB然后执行dbms_xdb_config.sethttpport
alter session set container=ORCLPDB1;
exec dbms_xdb_config.sethttpport(5505);
Oracle 12c EM express
原文：https://www.cnblogs.com/cnmarkao/p/9926149.html
