Oracle錯誤解決：ORA-12519, TNS:no appropriate service handler found

問題：java.sql.SQLException: Listener refused the connection with the following error:

ORA-12519, TNS:no appropriate service handlerfound

解決：超過連接數，所以要擴大。在oracle中執行sql語句

select value from v$parameter where name ='processes'; 取得進程數的上限。

alter system set processes = 300 scope =spfile; 重新設置連接數

alter system set sessions=335 scope=spfile; 設置SESSIONS = PROCESSES * 1.1 + 5

重啓數據庫:
shutdown immediate;
startup;