PLSQL Developer 配置，在

E:\tools\oracle\product\11.2.0\dbhome_1\NETWORK\ADMIN 下也有tnsnames文件，启动PLSQL Developer一般检测该目录下的tnsnames ， 但是你的配置

系统变量ORACLE_HOME且值为E:\tools\oracle\product\11.2.0\dbhome_1（以自己的oracle安装目录为准），配置文件内容为

# tnsnames.ora Network Configuration File: F:\tools\oracles\product\11.2.0\dbhome_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

LISTENER_ORCL =
  (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))


ORACLR_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
    (CONNECT_DATA =
      (SID = CLRExtProc)
      (PRESENTATION = RO)
    )
  )

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )