application cannot connect to database server for query

Hi, all:

I got an urgent production issue this morning, the JBOSS application server cannot connect to database servers. The server.log file from Jboss shows as below. The database tier is a clustered oracle 10g database, please help.

2016-03-28 11:12:36,837 1101737373 WARN  [org.jboss.resource.connectionmanager.JBossManagedConnectionPool] (JCA PoolFiller:) Unable to fill pool
org.jboss.resource.JBossResourceException: Could not create connection; - nested throwable: (java.sql.SQLException: Io exception: The Network Adapter could not establish the connection)
                at org.jboss.resource.adapter.jdbc.xa.XAManagedConnectionFactory.createManagedConnection(XAManagedConnectionFactory.java:155)
                at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.createConnectionEventListener(InternalManagedConnectionPool.java:619)
                at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.fillToMin(InternalManagedConnectionPool.java:534)
                at org.jboss.resource.connectionmanager.PoolFiller.run(PoolFiller.java:74)
                at java.lang.Thread.run(Thread.java:701)
Caused by: java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
                at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:125)
                at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:162)
                at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:274)
                at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:319)
                at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:344)
                at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:148)
                at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
                at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:545)
                at oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:194)
                at oracle.jdbc.pool.OracleConnectionPoolDataSource.getPhysicalConnection(OracleConnectionPoolDataSource.java:121)
                at oracle.jdbc.xa.client.OracleXADataSource.getXAConnection(OracleXADataSource.java:320)
                at oracle.jdbc.xa.client.OracleXADataSource.getXAConnection(OracleXADataSource.java:84)
                at org.jboss.resource.adapter.jdbc.xa.XAManagedConnectionFactory.createManagedConnection(XAManagedConnectionFactory.java:137)
                ... 4 more