Servlet过滤器使用

/** * */ package com.java.filter; 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; /** *@project FilterDemo *@Description:$<p>未登录则拦截的过滤器</p>$ *@Author mayun *@Title:LoginFilter.java *@Date:2013-11-2 上午10:49:08 */ public class LoginFilter implements Filter { public static HttpSession session; /* (non-Javadoc) * @see javax.servlet.Filter#destroy() */ @Override public void destroy() { } /* (non-Javadoc) * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) */ @Override public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) arg0; HttpServletResponse response = (HttpServletResponse) arg1; session = request.getSession(); String userName = (String) session.getAttribute("UserName"); System.out.println(userName+"==========="); if(null == userName || "".equals(userName)){ System.out.println("。。。未登陆。。。"); response.sendRedirect("../index.jsp"); return; } System.out.println("过滤通过"+userName); arg2.doFilter(request, response); } /* (non-Javadoc) * @see javax.servlet.Filter#init(javax.servlet.FilterConfig) */ @Override public void init(FilterConfig arg0) throws ServletException { } }