authenticationfilter.java

该系统是一个留言本

package com.v512.guestbook;

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.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class AuthenticationFilter implements Filter {
	String url = "/";

	public void destroy() {
	}

	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
			ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse res = (HttpServletResponse) response;
		HttpSession session = req.getSession();
		if (session.getAttribute("guestbook.admin.username") == null) {
			res.sendRedirect(req.getContextPath() + url);
			return ;
		}
		chain.doFilter(request, response);
	}

	public void init(FilterConfig config) throws ServletException {
		url = config.getInitParameter("url");

	}

}