[sql] The network adapter could not establish the connection - Oracle 11g

I wrote a servlet program and I want it to connect to my Oracle database but its giving me an error. I am using Eclipse Helios, Tomcat 6.0.37, Oracle 11g (11.2.0.1.0), ojdbc6.jar(added in run configuration of the Server project). I am able to connect to the database through the SQL Plus interface and even can start a connection from Eclipse's database development perspective. But when i am trying to connect through my servlet I am getting the error. For my servlet i am using the port number 9090 and for the database the default 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

This is my code for establishing the connection:

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

I tried executing the lsnrctl stat command and this was the result:

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

These are the contents of my tnsnames.ora file:

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)
    )
  )

Any help would be appreciated. Thanks in advance.

First check your listener is on or off. Go to net manager then Local -> service naming -> orcl. Then change your HOST NAME and put your PC name. Now go to LISTENER and change the HOST and put your PC name.

I had the similar issue. its resolved for me with a simple command.

lsnrctl start

The Network Adapter exception is caused because:

1. The database host name or port number is wrong (OR)
2. The database TNSListener has not been started. The TNSListener may be started with the lsnrctl utility.

Try to start the listener using the command prompt:

1. Click Start, type cmd in the search field, and when cmd shows up in the list of options, right click it and select ‘Run as Administrator’.
2. At the Command Prompt window, type lsnrctl start without the quotes and press Enter.
3. Type Exit and press Enter.

Hope it helps.