Java Servlet - @WebFilter Examples

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

@WebFilter(filterName = "profiler",
        urlPatterns = {"/search/*"},
        initParams = @WebInitParam(name = "env", value = "dev"))
public class Profiler implements Filter {

    private FilterConfig filterConfig;

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException {

        if ("dev".equals(filterConfig.getInitParameter("env"))) {
            long time = System.currentTimeMillis();
            chain.doFilter(request, response);

            time = System.currentTimeMillis() - time;
            String url = request instanceof HttpServletRequest ?
                    ((HttpServletRequest) request).getRequestURL().toString() : "N/A";

            System.out.println("Time taken for request to complete:  " + time
                    + "ms");
            System.out.println("Request url : " + url);
        } else {
            chain.doFilter(request, response);
        }
    }

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


    @Override
    public void destroy() {
    }
}

package com.logicbig.example;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Collections;

@WebFilter(urlPatterns = {"/*"})
public class HeaderLogFilter implements Filter {

    @Override
    public void init (FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter (ServletRequest request, ServletResponse response,
                          FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse rep = (HttpServletResponse) response;

        System.out.println("----- Request ---------");
        Collections.list(req.getHeaderNames())
                   .forEach(n -> System.out.println(n + ": " + req.getHeader(n)));

        chain.doFilter(request, response);

        System.out.println("----- response ---------");

        rep.getHeaderNames()
           .forEach(n -> System.out.println(n + ": " + rep.getHeader(n)));

        System.out.println("response status: " + rep.getStatus());
    }

    @Override
    public void destroy () {
    }
}