Use Filter to log Configuration : Filter « Servlet « Java Tutorial

1. Java Tutorial
2. Servlet
3. Filter

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

public class MyServlet implements Filter 
{
  private FilterConfig filterConfig = null;

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

    long start = System.currentTimeMillis();
    String address =  request.getRemoteAddr();
    String file = ((HttpServletRequest) request).getRequestURI();
        
    chain.doFilter(request, response);

    filterConfig.getServletContext().log(
        "User access! " +      
        " User IP: " + address +      
        " Resource: " + file + 
        " Milliseconds used: " + (System.currentTimeMillis() - start) 
    );
  }

  public void destroy() { }

  public void init(FilterConfig filterConfig) {
    this.filterConfig = filterConfig;
  }
}

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
    "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">

<web-app>

  <filter>
    <filter-name>Simple Filter</filter-name>
    <filter-class>MyServlet</filter-class>
    <init-param>
      <param-name>message</param-name>
      <param-value>Hello!</param-value>
    </init-param>    
  </filter>
  <filter-mapping>
    <filter-name>Simple Filter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>  
  
</web-app>

25.17.Filter
	25.17.1.	Your First Filter
	25.17.2.	Filter Response
	25.17.3.	Servlet Filter Init Parameter
	25.17.4.	Use Filter to log Configuration
	25.17.5.	Use Filter to check Request Parameter
	25.17.6.	Use Filter to Check Date
	25.17.7.	Simple filter for measuring servlet response times
	25.17.8.	Filter that uses a response wrapper to convert all output to uppercase