Java: how to declare a servlet filter

Place the following declaration in the tomcat conf/web.xml directory:

<filter>
  <filter-name>nome do filtro</filter-name>
  <filter-class>pacote.class</filter-class>
  <init-param>
    <param-name>nome do parametro</param-name>
    <param-value>valor do parametro</param-value>
  </init-param>
</filter>

<filter-mapping>
  <filter-name>nome do filtro definido na sessão filter</filter-name>
  <!-- contexto onde o filtro será aplicado -->
  <!-- /* para todos os contextos -->
  <url-pattern>/*</url-pattern>
</filter-mapping>

JAVA:
Add servlet-api library version 2.5 minimum

Implement the following methods:

public void init(FilterConfig paramFilterConfig)
	throws ServletException;

public void doFilter(ServletRequest paramServletRequest,
		ServletResponse paramServletResponse,
		FilterChain paramFilterChain)
	throws IOException, ServletException;

public void destroy();

Compile and copy jar to the tomcat /lib directory.