求救- oracle-jdbc

java.sql.SQLException: Io 异常: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=150999297)(ERR=12505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4))))
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:180)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:222)
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:335)
at oracle.jdbc.driver.OracleConnection.<init>(OracleConnection.java:361)
at oracle.jdbc.driver.OracleDriver.getConnectionInstance(OracleDriver.java:442)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:321)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at com.sccp.rugosa.server.DAO.Tools.createConn(Tools.java:42)
at com.sccp.rugosa.server.DAO.DBOperation.query(DBOperation.java:79)
at com.sccp.rugosa.server.BL.ServerParseMessage.parseLoginMessage(ServerParseMessage.java:94)
at com.sccp.rugosa.server.BL.ServerParseMessage.parseType(ServerParseMessage.java:52)
at com.sccp.rugosa.server.communication.ServerConnectionProcessThread.run(ServerConnectionProcessThread.java:53)
Exception in thread "Thread-3" java.lang.NullPointerException
at com.sccp.rugosa.server.DAO.DBOperation.query(DBOperation.java:80)
at com.sccp.rugosa.server.BL.ServerParseMessage.parseLoginMessage(ServerParseMessage.java:94)
at com.sccp.rugosa.server.BL.ServerParseMessage.parseType(ServerParseMessage.java:52)
at com.sccp.rugosa.server.communication.ServerConnectionProcessThread.run(ServerConnectionProcessThread.java:53)