Escribí un programa de servlets y quiero que se conecte a mi base de datos Oracle, pero me está dando un error. Estoy utilizando Eclipse Helios, Tomcat 6.0.37, Oracle 11g (11.2.0.1.0), ojdbc6.jar (agregado en la configuración de ejecución del proyecto del servidor). Puedo conectarme a la base de datos a través de la interfaz SQL Plus e incluso puedo iniciar una conexión desde la perspectiva del desarrollo de la base de datos de Eclipse. Pero cuando intento conectarme a través de mi servlet, aparece el error. Para mi servlet estoy usando el número de puerto 9090 y para la base de datos el predeterminado 1521.

java.sql.SQLException: The Network Adapter could not establish the connection
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:412)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:531)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:221)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:503)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at java.sql.DriverManager.getConnection(Unknown Source)
    at com.android.collegenotificationsystem.RegistrationServlet.doGet(RegistrationServlet.java:43)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Unknown Source)
Caused by: oracle.net.ns.NetException: The Network Adapter could not establish the connection
    at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:359)
    at oracle.net.resolver.AddrResolution.resolveAndExecute(AddrResolution.java:422)
    at oracle.net.ns.NSProtocol.establishConnection(NSProtocol.java:672)
    at oracle.net.ns.NSProtocol.connect(NSProtocol.java:237)
    at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1042)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:301)
    ... 21 more
Caused by: java.net.ConnectException: Connection refused: connect
    at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
    at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
    at java.net.PlainSocketImpl.connect(Unknown Source)
    at java.net.SocksSocketImpl.connect(Unknown Source)
    at java.net.Socket.connect(Unknown Source)
    at oracle.net.nt.TcpNTAdapter.connect(TcpNTAdapter.java:141)
    at oracle.net.nt.ConnOption.connect(ConnOption.java:123)
    at oracle.net.nt.ConnStrategy.execute(ConnStrategy.java:337)
    ... 26 more

Este es mi código para establecer la conexión:

Class.forName("oracle.jdbc.OracleDriver"); Connection con = (Connection) DriverManager.getConnection( "jdbc:oracle:thin:@localhost:1521:orcl","username","password");

Intenté ejecutar el comando lsnrctl stat y este fue el resultado:

LSNRCTL for 32-bit Windows: Version 11.2.0.1.0 - Production on 03-AUG-2013 16:08
:46

Copyright (c) 1991, 2010, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for 32-bit Windows: Version 11.2.0.1.0 - Produ
ction
Start Date                03-AUG-2013 12:14:19
Uptime                    0 days 3 hr. 54 min. 28 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   C:\app\Owner\product\11.2.0\dbhome_1\network\admin\lis
tener.ora
Listener Log File         c:\app\owner\diag\tnslsnr\Owner-PC\listener\alert\log.
xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(PIPENAME=\\.\pipe\EXTPROC1521ipc)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1521)))
Services Summary...
Service "CLRExtProc" has 1 instance(s).
  Instance "CLRExtProc", status UNKNOWN, has 1 handler(s) for this service...
Service "orcl.168.1.56" has 1 instance(s).
  Instance "orcl", status READY, has 1 handler(s) for this service...
Service "orclXDB.168.1.56" has 1 instance(s).
  Instance "orcl", status READY, has 1 handler(s) for this service...
The command completed successfully

Estos son los contenidos de mi archivo tnsnames.ora:

LISTENER_ORCL =
  (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))


ORACLR_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
    (CONNECT_DATA =
      (SID = CLRExtProc)
      (PRESENTATION = RO)
    )
  )

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl.168.1.56)
    )
  )

Cualquier ayuda sería apreciada. Gracias por adelantado.