步骤1：检查客户端的tnsnames.ora

/usr/app/oracle/product/11.2.0/network/admin/tnsnames.ora

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = **数据库服务器IP** )(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = **orcl**)
    )
  )

步骤2：检查服务器listener.ora

/usr/app/oracle/product/11.2.0/network/admin/listener.ora

SID_LIST_LISTENER=(
    (SID_LIST=
        (SID_DESC=
            。。。省略。。。
        )
        (SID_DESC=
            (SID_NAME= **orcl** )
            (ORACLE_HOME= **dbhome_1的目录地址**)
        )
    )
)
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = **数据库服务器IP** )(PORT = 1521))
    )
  )

ADR_BASE_LISTENER = /usr/app/oracle

步骤3：重启监听

lsnrctl stop

lsnrctl start