usertracefilter.java

JSP线上水球游戏开发环境Tomcat 5.5.x + JDK 5.0（不要在JDK 1.4.x的JVM上跑）

package com.andowson.onlineuser;

import java.io.IOException;
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.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/**
 * UserTraceFilter
 *
 * @version 0.0.1 2004/12/22
 * @author Andowson Chang
 */
public class UserTraceFilter implements Filter {

    protected FilterConfig filterConfig;
    private final static String FILTER_APPLIED = "_usertrace_filter_applied";

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        // Ensure that filter is only applied once per session.
        HttpSession session = ((HttpServletRequest) request).getSession();
        if (session.getAttribute(FILTER_APPLIED) == null) {
            System.out.println("Applying usertrace filter to request.");
            session.setAttribute(FILTER_APPLIED, Boolean.TRUE);
            
            UserTrace user = new UserTrace();
            user.addRequest((HttpServletRequest) request);
            /*System.out.println("sessionId: " + user.getSessionId());
	  	      System.out.println("username: " + user.getUsername());
	  	      System.out.println("hostname: " + user.getHostname());
	  	      System.out.println("start: " + user.getStart());
	  	      System.out.println("lastRequest: " + user.getLastRequest());*/
            session.setAttribute("user", user);
        }
        else {
            System.out.println("Usertrace filter already applied, ignoring it.");
        }
        // pass the request on
        chain.doFilter(request, response);
    }

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

    public void destroy() {
    }
}