Java四个有用的过滤器Filter

一、使浏览器不缓存页面的过滤器    
import javax.servlet.*;   
import javax.servlet.http.HttpServletResponse;   
import java.io.IOException;   
  
  
public class ForceNoCacheFilter implements Filter {   
  
public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException   
{   
   ((HttpServletResponse) response).setHeader("Cache-Control","no-cache");   
   ((HttpServletResponse) response).setHeader("Pragma","no-cache");   
   ((HttpServletResponse) response).setDateHeader ("Expires", -1);   
   filterChain.doFilter(request, response);   
}   
  
public void destroy()   
{   
}   
  
     public void init(FilterConfig filterConfig) throws ServletException   
{   
}   
}   
  
二、检测用户是否登陆的过滤器   
  
import javax.servlet.*;   
import javax.servlet.http.HttpServletRequest;   
import javax.servlet.http.HttpServletResponse;   
import javax.servlet.http.HttpSession;   
import java.util.List;   
import java.util.ArrayList;   
import java.util.StringTokenizer;   
import java.io.IOException;   
  
  
public class CheckLoginFilter   
implements Filter   
{   
     protected FilterConfig filterConfig = null;   
     private String redirectURL = null;   
     private List notCheckURLList = new ArrayList();   
     private String sessionKey = null;   
  
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException   
{   
   HttpServletRequest request = (HttpServletRequest) servletRequest;   
   HttpServletResponse response = (HttpServletResponse) servletResponse;   
  
    HttpSession session = request.getSession();   
   if(sessionKey == null)   
   {   
    filterChain.doFilter(request, response);   
    return;   
   }   
   if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(sessionKey) == null)   
   {   
    response.sendRedirect(request.getContextPath() + redirectURL);   
    return;   
   }   
   filterChain.doFilter(servletRequest, servletResponse);   
}   
  
public void destroy()