JAVA五個有用的過濾器.docx

五個有用的過濾器一、 使瀏覽器不緩存頁面的過濾器import javax.servlet.*; import javax.servlet.http.HttpServletResponse; import java.io.IOException; /* * 用于的使 Browser 不緩存頁面的過濾器 */ 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、檢測用戶是否登陸的過濾器 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; /* * 用于檢測用戶是否登陸的過濾器，如果未登錄，則重定向到指的登錄頁面 * 配置參數(shù) * checkSessionKey 需檢查的在 Session 中保存的關(guān)鍵字 * redirectURL 如果用戶未登錄，則重定向到指定的頁面，URL不包括 ContextPath * notCheckURLList 不做檢查的URL列表，以分號分開，并且 URL 中不包括 ContextPath */ 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、字符編碼的過濾器 import javax.servlet.*; import java.io.IOException; /* * 用于設(shè)置 HTTP 請求字符編碼的過濾器，通過過濾器參數(shù)encoding指明使用何種字符編碼,用于處理Html Form請求參數(shù)的中文問題 */ 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); 四、資源保護過濾器 package catalog.view.util; import javax.servlet.Filter; import javax.servlet.FilterConfig; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import java.io.IOException; import java.util.Iterator; import java.util.Set; import java.util.HashSet; / import mons.logging.Log; import mons.logging.LogFactory; /* * This Filter class handle the security of the application. * * It should be configured inside the web.xml. * * author Derek Y. Shen */ public class SecurityFilter implements Filter /the login page uri private static final String LOGIN_PAGE_URI = login.jsf; /the logger object private Log logger = LogFactory.getLog(this.getClass(); /a set of restricted resources private Set restrictedResources; /* * Initializes the Filter. */ public void init(FilterConfig filterConfig) throws ServletException this.restrictedResources = new HashSet(); this.restrictedResources.add(/createProduct.jsf); this.restrictedResources.add(/editProduct.jsf); this.restrictedResources.add(/productList.jsf); /* * Standard doFilter object. */ public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException this.logger.debug(doFilter); String contextPath = (HttpServletRequest)req).getContextPath(); String requestUri = (HttpServletRequest)req).getRequestURI(); this.logger.debug(contextPath = + contextPath); this.logger.debug(requestUri = + requestUri); if (this.contains(requestUri, contextPath) & !this.authorize(HttpServletRequest)req) this.logger.debug(authorization failed); (HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req, res); else this.logger.debug(authorization succeeded); chain.doFilter(req, res); public void destroy() private boolean contains(String value, String contextPath) Iterator ite = this.restrictedResources.iterator(); while (ite.hasNext() String restrictedResource = (String)ite.next(); if (contextPath + restrictedResource).equalsIgnoreCase(value) return true; return false; private boolean authorize(HttpServletRequest req) /處理用戶登錄 /* UserBean user = (UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN); if (user != null & user.getLoggedIn() /user logged in return true; else return false; */ 五 利用Filter限制用戶瀏覽權(quán)限 在一個系統(tǒng)中通常有多個權(quán)限的用戶。不同權(quán)限用戶的可以瀏覽不同的頁面。使用Filter進行判斷不僅省下了代碼量，而且如果要更改的話只需要在Filter文件里動下就可以。 以下是Filter文件代碼： 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; public class RightFilter implements Filter public void destroy() public void doFilter(ServletRequest sreq, ServletResponse sres, FilterChain arg2) throws IOException, ServletException / 獲取uri地址 HttpServletRequest request=(HttpServletRequest)sreq; String