使用PL/SQL Developer连接Oracle11G时出现了12541和12514错误

使用PL/SQL Developer连接Oracle11G时出现了12541和12514错误，解决方法如下：

出现12541错误(无监听程序)时可修改app\user\product\11.1.0\db_1\network\admin\listener.ora文件 ,验证如下内容
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1522))
    )
  )
与app\user\product\11.1.0\db_1\NETWORK\ADMIN\tnsnames.ora文件中的如下内容一致：
ORCL =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1522))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )
即HOST与PORT要一致。
如果出现12514错误(无法识别标识),可修改app\user\product\11.1.0\db_1\network\admin\listener.ora，添加如下内容：
SID_LIST_LISTENER =
(SID_LIST =
 (SID_DESC =
  (SID_NAME = PLSExtProc)
  (ORACLE_HOME = /app/user/product/11.1.0/db_1)
  (PROGRAM = extproc)
 )
 (SID_DESC =
  (GLOBAL_DBNAME = orcl)
  (ORACLE_HOME = /app/user/product/11.1.0/db_1)
  (SID_NAME = orcl)
 )
)