oracle 11g ORA-12514: TNS: 监听程序当前无法识别连接描述符中请求的服务

 # listener.ora Network Configuration File: D:\app\Administrator\product\11.1.0\db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
  (SID_DESC =(SID_NAME = PLSExtProc)(ORACLE_HOME = D:\app\Administrator\product\11.1.0\db_1)(PROGRAM = extproc))

  (SID_DESC = (GLOBAL_DBNAME = ORCL)(ORACLE_HOME = D:\app\Administrator\product\11.1.0\db_1)(SID_NAME = ORCL))
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    )
  )

经常碰到这种问题，只是重启一下服务，就可以了。今天启动了3遍都不行，上网找了一下，问题解决了。