import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public abstract class HttpFilter implements Filter
{
??? private FilterConfig config;
???
??? //////////////////////////////////
??? public void init(FilterConfig config) throws ServletException
??? {
??????? this.config = config;
??????? init();
??? }
???
??? public void init() throws ServletException
??? {
??? }
??? ///////////////////////////////
??? public FilterConfig getFilterConfig()
??? {
??????? return config;
??? }
???
??? public String getInitParameter(String name)
??? {
??????? return config.getInitParameter(name);
??? }
???
??? public ServletContext getServletContext()
??? {
??????? return config.getServletContext();
??? }
???
??? public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
??????????????????????????????????????????????? throws IOException, ServletException
??? {
??????? doFilter((HttpServletRequest)request, (HttpServletResponse)response, chain);
??? }
???
??? public abstract void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
??????????????????????????????????????????????? throws IOException, ServletException;
???
??? public void destroy()
??? {
??? }
}