几种常用过滤器

sd8089730

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;/** * 用于的使 Browser 不缓存页面的过滤器 */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;/** * 用于检测用户是否登陆的过滤器，如果未登录，则重定向到指的登录页面<p> * 配置参数<p> * checkSessionKey 需检查的在 Session 中保存的关键字<br/> * redirectURL 如果用户未登录，则重定向到指定的页面，URL不包括 ContextPath<br/> * notCheckURLList 不做检查的URL列表，以分号分开，并且 URL 中不包括 ContextPath<br/> */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() {  notCheckURLList.clear(); } private boolean checkRequestURIIntNotFilterList(HttpServletRequest request) {  String uri = request.getServletPath() + (request.getPathInfo() == null ? "" : request.getPathInfo());  return notCheckURLList.contains(uri); } public void init(FilterConfig filterConfig) throws ServletException {  this.filterConfig = filterConfig;  redirectURL = filterConfig.getInitParameter("redirectURL");  sessionKey = filterConfig.getInitParameter("checkSessionKey");  String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList");  if(notCheckURLListStr != null)  {   StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");   notCheckURLList.clear();   while(st.hasMoreTokens())   {    notCheckURLList.add(st.nextToken());   }  } }}三、字符编码的过滤器import javax.servlet.*;import java.io.IOException;/** * 用于设置 HTTP 请求字符编码的过滤器，通过过滤器参数encoding指明使用何种字符编码,用于处理Html Form请求参数的中文问题 */public class CharacterEncodingFilter implements Filter{ protected FilterConfig filterConfig = null; protected String encoding = ""; public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {        if(encoding != null)         servletRequest.setCharacterEncoding(encoding);        filterChain.doFilter(servletRequest, servletResponse); } public void destroy() {  filterConfig = null;  encoding = null; }    public void init(FilterConfig filterConfig) throws ServletException {         this.filterConfig = filterConfig;        this.encoding = filterConfig.getInitParameter("encoding"); }}