loginfilter.java

这是一个网上考试系统,主要是用java和jsp写的.

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(){}
}