前言:网上有很多解决办法，删listener.ora也好，还是什么也好，都解决不了我这个问题，依然报12514错误，以下是我逐个尝试后成功的监听字符串。。
listener.ora文件：
# listener.ora Network Configuration File: d:/app/john/product/11.1.0/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = cjtfs)
(ORACLE_HOME = d:/app/john/product/11.1.0/db_1)
(PROGRAM = cjtfs)
)
(SID_DESC =
(GLOBAL_DBNAME = cjtfs)
(ORACLE_HOME = d:/app/john/product/11.1.0/db_1)
(SID_NAME = cjtfs)
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = john-PC)(PORT = 1521))
)
)
tnsnames.ora文