数据库异常怎么办？

oracle.javatools.db.DBException: java.sql.SQLRecoverableException: IO 错误: The Network Adapter could not establish the connection
at oracle.jdevimpl.db.adapter.CADatabaseFactory.createConnectionImpl(CADatabaseFactory.java:66)
at oracle.javatools.db.DatabaseFactory.createConnection(DatabaseFactory.java:534)
at oracle.javatools.db.DatabaseFactory.createDatabase(DatabaseFactory.java:208)
at oracle.jdeveloper.db.DatabaseConnections.getDatabase(DatabaseConnections.java:607)
at oracle.dbtools.raptor.utils.Connections$ConnectionInfo.getDatabase(Connections.java:172)
at oracle.dbtools.raptor.utils.Connections.getConnection(Connections.java:1064)
at oracle.dbtools.raptor.utils.Connections.getConnection(Connections.java:1045)
at oracle.dbtools.worksheet.editor.Worksheet$WorksheetController.testConnection(Worksheet.java:570)
at oracle.dbtools.worksheet.editor.Worksheet$WorksheetController.access$700(Worksheet.java:422)
at oracle.dbtools.worksheet.editor.Worksheet$WorksheetController$1.doWork(Worksheet.java:443)
at oracle.dbtools.raptor.backgroundTask.RaptorTask.call(RaptorTask.java:193)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at oracle.dbtools.raptor.backgroundTask.RaptorTaskManager$RaptorFutureTask.run(RaptorTaskManager.java:515)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.sql.SQLRecoverableException: IO 错误: The Network Adapter could not establish the connection
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:475)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:552)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:253)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:526)
at oracle.jdeveloper.db.adapter.AbstractConnectionCreator.getConnection(AbstractConnectionCreator.java:153)
at oracle.dbtools.raptor.standalone.connection.RaptorConnectionCreator.getConnection(RaptorConnectionCreator.java:195)
at oracle.dbtools.raptor.dialogs.conn.ConnectionPrompt.promptForPassword(ConnectionPrompt.java:67)
at oracle.jdeveloper.db.adapter.DatabaseProvider.getConnection(DatabaseProvider.java:321)
at oracle.jdeveloper.db.adapter.DatabaseProvider.getConnection(DatabaseProvider.java:254)
at oracle.jdevimpl.db.adapter.CADatabaseFactory.createConnectionImpl(CADatabaseFactory.java:60)
... 19 more
Caused by: oracle.net.ns.NetException: The Network Adapter could not establish the connection
at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:439)
at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:434)
at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:687)
at oracle.net.ns.NSProtocol.connect(NSProtocol.java:247)
at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1126)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:337)
... 29 more
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:149)
at oracle.net.nt.ConnOption.connect(ConnOption.java:133)
at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:405)

... 34 more