转载：https://blog.csdn.net/haha_201510/article/details/88119587

centOS环境下的解决方案：

查看监听状态lsnrctl status

如果有监听，则如下图，显示有服务orcl(服务名)监听。

如果没有监听，查看监听文件

cd /u01/app/oracle/product/11.2.0/db_1/network/admin

tnsnames.ora:用于客户端,提示客户端从哪个监听实例连接。

LISTENER_ORCL =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))

ORCL =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
)
)

listener.ora：用于服务端，用于提示服务端监听哪些实例。

LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
(ADDRESS = (PROTOCOL = TCP)(HOST =localhost.localdomain)(PORT = 1521))
# (ADDRESS = (PROTOCOL = TCP)(HOST =192.168.0.105)(PORT = 1521))
)
)
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = orcl)
(ORACLE_HOME = /u01/app/oracle/product/11.2.0/db_1/)
(SID_NAME = ORCL)
)
)
#PS: 这里面的SID_NAME是oracle实例名，GLOBAL_DBNAME是全局的dbname，是db_unique_name

LISTENER =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = localhost.localdomain)(PORT = 1521))
)

ADR_BASE_LISTENER = /u01/app/oracle

其中HOST为当前主机名（可以使用本机的IP地址）。

注意：当前我的hosts文件的配置如下

[root@192 etc]# vim /etc/hosts

127.0.0.1 localhost localhost.localdomain
::1 localhost localhost.localdomain