警告: SQL Error: 0, SQLState: null,严重: Cannot create PoolableConnectionFactory,该怎么解决

警告: SQL Error: 0, SQLState: null2010-4-20 13:34:50 org.hibernate.util.JDBCExceptionReporter logExceptions严重: Cannot create PoolableConnectionFactory2010-4-20 13:34:50 org.hibernate.cfg.SettingsFactory buildSettings警告: Could not obtain connection metadataorg.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory, cause: java.sql.SQLException: Io 异常: The Network Adapter could not establish the connection    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:146)    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:255)    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:387)    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:441)    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:165)    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:35)    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:801)    at org.apache.commons.dbcp.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:82)    at org.apache.commons.dbcp.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:300)    at org.apache.commons.dbcp.BasicDataSource.validateConnectionFactory(BasicDataSource.java:838)    at org.apache.commons.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:821)    at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:518)    ..