Does not implement javax.servlet.Servlet

Question

I have a filter class
public class SessionFilter implements Filter{
public void init(FilterConfig filterConfig) throws ServletException
// do nothing here
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException,
ServletException
<< here i get the login information and populate one of our user defined object and set this object as
request.getSession().setAttribute("SESSION_OBJECT", <<user defined object>>); >>
public void destroy()
// anything to destroy ?
And below is my entry in web.xml file
<filter>
<filter-name>SessionFilter</filter-name>
<display-name>Session Filter</display-name>
<description>Session Filter</description>
<filter-class><<class path>></filter-class>
</filter>
<filter-mapping>
<filter-name>SessionFilter</filter-name>
<url-pattern>/myapp/*</url-pattern>
</filter-mapping>
I am getting following error
javax.servlet.ServletException: Servlet class: 'com.emc.eserv.login.filter.SessionFilter' does not implement javax.servlet.Servlet
     at weblogic.servlet.internal.StubSecurityHelper$ServletInitAction.run(StubSecurityHelper.java:275)
     at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
     at weblogic.security.service.SecurityManager.runAs(Unknown Source)
     at weblogic.servlet.internal.StubSecurityHelper.createServlet(StubSecurityHelper.java:63)
     at weblogic.servlet.internal.StubLifecycleHelper.createOneInstance(StubLifecycleHelper.java:58)
     at weblogic.servlet.internal.StubLifecycleHelper.<init>(StubLifecycleHelper.java:48)
     at weblogic.servlet.internal.ServletStubImpl.prepareServlet(ServletStubImpl.java:504)
     at weblogic.servlet.internal.WebAppServletContext.preloadServlet(WebAppServletContext.java:1830)
     at weblogic.servlet.internal.WebAppServletContext.loadServletsOnStartup(WebAppServletContext.java:1807)
     at weblogic.servlet.internal.WebAppServletContext.preloadResources(WebAppServletContext.java:1727)
     at weblogic.servlet.internal.WebAppServletContext.start(WebAppServletContext.java:2890)
     at weblogic.servlet.internal.WebAppModule.startContexts(WebAppModule.java:948)
     at weblogic.servlet.internal.WebAppModule.start(WebAppModule.java:353)
     at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:204)
     at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
     at weblogic.application.internal.flow.ModuleStateDriver.start(ModuleStateDriver.java:60)
     at weblogic.application.internal.flow.ScopedModuleDriver.start(ScopedModuleDriver.java:200)
     at weblogic.application.internal.flow.ModuleListenerInvoker.start(ModuleListenerInvoker.java:117)
     at weblogic.application.internal.flow.ModuleStateDriver$3.next(ModuleStateDriver.java:204)
     at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
     at weblogic.application.internal.flow.ModuleStateDriver.start(ModuleStateDriver.java:60)
     at weblogic.application.internal.flow.StartModulesFlow.activate(StartModulesFlow.java:26)
     at weblogic.application.internal.BaseDeployment$2.next(BaseDeployment.java:635)
     at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
     at weblogic.application.internal.BaseDeployment.activate(BaseDeployment.java:212)
     at weblogic.application.internal.DeploymentStateChecker.activate(DeploymentStateChecker.java:154)
     at weblogic.deploy.internal.targetserver.AppContainerInvoker.activate(AppContainerInvoker.java:80)
     at weblogic.deploy.internal.targetserver.operations.AbstractOperation.activate(AbstractOperation.java:566)
     at weblogic.deploy.internal.targetserver.operations.ActivateOperation.activateDeployment(ActivateOperation.java:136)
     at weblogic.deploy.internal.targetserver.operations.ActivateOperation.doCommit(ActivateOperation.java:104)
     at weblogic.deploy.internal.targetserver.operations.AbstractOperation.commit(AbstractOperation.java:320)
     at weblogic.deploy.internal.targetserver.DeploymentManager.handleDeploymentCommit(DeploymentManager.java:816)
     at weblogic.deploy.internal.targetserver.DeploymentManager.activateDeploymentList(DeploymentManager.java:1223)
     at weblogic.deploy.internal.targetserver.DeploymentManager.handleCommit(DeploymentManager.java:434)
     at weblogic.deploy.internal.targetserver.DeploymentServiceDispatcher.commit(DeploymentServiceDispatcher.java:161)
     at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.doCommitCallback(DeploymentReceiverCallbackDeliverer.java:181)
Could you guys tell me what i am doing wrong ?

Answer 1

To get some response at the client side, you should invoke a Servlet or a JSP page.
Put a JSP file in /webapp/test.jsp or so and invoke it. Then the Filter will be invoked as well. The Filters aren't there to send some output to the client, but to intercept requests and responses and if necessary make changes to one or both of them.