ORA-12514: TNS: 监听程序当前无法识别连接描述符中请求的服务

关于oracle客户端链接服务报错问题解决：
ORA-12514: TNS: 监听程序当前无法识别连接描述符中请求的服务
我主要是修改了listener.ora这个文件然后重启oracle监听服务，问题就解决了。
修改内容如下：
修改前的内容：
# listener.ora Network Configuration File: E:\app\Candy\product\11.2.0\dbhome_1\NETWORK\ADMIN\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = E:\app\Candy\product\11.2.0\dbhome_1)
      (PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:E:\app\Candy\product\11.2.0\dbhome_1\bin\oraclr11.dll")
    )
  )

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

ADR_BASE_LISTENER = E:\app\Candy
修改后的内容：
# listener.ora Network Configuration File: E:\app\Candy\product\11.2.0\dbhome_1\NETWORK\ADMIN\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = orcl)  
      (ORACLE_HOME = E:\app\Candy\product\11.2.0\dbhome_1)
      (PROGRAM = orcl)
    )
     (SID_DESC =
      (GLOBAL_DBNAME = orcl)
      (ORACLE_HOME = E:\app\Candy\product\11.2.0\dbhome_1)
      (SID_NAME = orcl)
    )
  )
LISTENER =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
  )

ADR_BASE_LISTENER = E:\app\Candy