<filter> <filter-name>EncodingFilter</filter-name> <filter-class>Shiyan6.EncodingFilter</filter-class> </filter>

这是一个在web.xml中配置filter的例子，其中filter-name指定了filter的名称，filter-class指定了filter的类名。在init-param标签中可以设置filter的初始化参数。在filter-mapping标签中可以指定filter要拦截的url-pattern。具体实现可以参考以下代码：

public class EncodingFilter implements Filter {
    private String encoding;

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        encoding = filterConfig.getInitParameter("encoding");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        request.setCharacterEncoding(encoding);
        response.setCharacterEncoding(encoding);
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        encoding = null;
    }
}