package com.nova.colimas.web.filters;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.*;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import com.nova.colimas.web.bean.UserBean;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import org.apache.struts.Globals;
import org.apache.struts.action.*;
import com.nova.colimas.web.constants.Constants;

/**         * Filter implementation for user authentication。
必须实现Filter接口 *
@author DREAN* 
@version $Id: AuthenticationFilter.java,v 1.0 */
public class AuthenticationFilter implements Filter{                
/**         * filterConfig will store the reference of FilterConfig         */        
      
      private FilterConfig filterConfig;                
      private String onErrorUrl;     
   
/**         * store the reference of the FilterConfig.         
* @param config FilterConfig object         
* @throws ServletException         */        

      public void init(FilterConfig config) throws ServletException        
      {//获得验证失败forward地址                
              filterConfig = config;                
              onErrorUrl=filterConfig.getInitParameter("onError");                
              if (onErrorUrl==null || "".equals(onErrorUrl))
       {                        
                      onErrorUrl="/pages/index.jsp";                
               }        
       }        
/**         * User Authentication is  done. If User is authenticated successful then         
* control is transferred to logon URI         
* @param ServletRequest Request         
* @param ServletRequest Response         
* @param FilterChain Filter Chain         
* @throws ServletException,IOException         */        

       public void doFilter(ServletRequest request, ServletResponse response, FilterChain next)  throws 

IOException,ServletException        
      {                
             HttpServletRequest httpRequest = (HttpServletRequest)request;                
             HttpServletResponse httpResponse=(HttpServletResponse)response;                
             // Current session               
             HttpSession httpSession = httpRequest.getSession();
             //Session里是否有用户信息。                
             if (httpSession.getAttribute(Constants.USER_KEY) == null)                
             {                        
                      ActionErrors errors=new ActionErrors();                        
                      errors.add(ActionErrors.GLOBAL_ERROR,                                       
                      new ActionError("error authentication"));                        
                      httpRequest.setAttribute(Globals.ERROR_KEY,errors);                
                     //没有，验证失败forward到/pages/index.jsp        
                     httpRequest.getRequestDispatcher(onErrorUrl).forward(httpRequest,httpResponse);                
               }
              else
              //成果过滤Action结束                        
              next.doFilter(request,response);                        
       }        
/**         * destroy() method is called by the servlet container         */        
       public void destroy()        
       { .... }        
}