www.pudn.com > exam.rar > LoginFilter.java

package kaoshi.filter;  
 
import java.io.*; 
import javax.servlet.*; 
import javax.servlet.http.*; 
 
/** 
 * @version 2007-12-27 
 * @author Xiaofei  
 */ 
public class LoginFilter implements Filter{ 
	FilterConfig filterConfig; 
	 
	public void init(FilterConfig filterConfig) 
          throws ServletException{ 
    } 
     
    public void doFilter(ServletRequest request, 
                     ServletResponse response, 
                     FilterChain chain) 
              throws java.io.IOException,ServletException{ 
    	HttpServletRequest req = (HttpServletRequest)request; 
    	String monitor = (String)req.getSession().getAttribute("monitor"); 
    	if (monitor != null) { 
    		chain.doFilter(request,response); 
    	} else { 
    		PrintWriter out = response.getWriter(); 
    		out.println("Please login first!"); 
    	} 
	} 
	 
	public void destroy(){} 
}