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The moose likes Servlets and the fly likes Tomcat 4.0 problem with Filter class Big Moose Saloon
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Tomcat 4.0 problem with Filter class

Zhongwu Lin

Joined: Mar 06, 2001
Posts: 11
I can't compile the following file
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.ServletException;
public class SimpleFilter implements Filter
private FilterConfig filterConfig;
public void doFilter (ServletRequest request,
ServletResponse response,
FilterChain chain)
chain.doFilter (request, response);
} catch (IOException io) {
System.out.println ("IOException raised in SimpleFilter");
} catch (ServletException se) {
System.out.println ("ServletException raised in SimpleFilter");
public FilterConfig getFilterConfig()
return this.filterConfig;
public void setFilterConfig (FilterConfig filterConfig)
this.filterConfig = filterConfig;
I am using Jdk 1.4. and the servlet.jar ( from tomcat 4.0 ) is in the classpath.
I unjar servlet.jar and found out that in this jar file Filer class is defined as:
package javax.servlet;
// Imports
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;
import javax.servlet.FilterChain;
import javax.servlet.ServletResponse;
import javax.servlet.ServletRequest;
public abstract interface Filter {
// Methods
void destroy();
void doFilter(ServletRequest p0, ServletResponse p1,
FilterChain p2) throws IOException, ServletException;
void init(FilterConfig p0) throws ServletException;
From servlet spec. we don't have to implement

we only need to implement

My question:
What do I need to do in order to write servlet using new features in spect 2.3 such as Filter to run under tomcat?

I agree. Here's the link:
subject: Tomcat 4.0 problem with Filter class