常用JAVA过滤器用法

java 代码
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      
    
    
* 配置参数      
    
    
* checkSessionKey 需检查的在 Session 中保存的关键字     
    
* redirectURL 如果用户未登录，则重定向到指定的页面，URL不包括 ContextPath     
    
* notCheckURLList 不做检查的URL列表，以分号分开，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");       
      
}       
}      


  
四、资源保护过滤器   

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 org.apache.commons.logging.Log;       
import org.apache.commons.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) {       
      
               //处理用户登录       
        /* UserBean user = (UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);     
       
   if (user != null && user.getLoggedIn()) {     
    //user logged in     
    return true;     
   }     
   else {     
    return false;     
   }*/      
}       
}