urlfilter.java

用jsp做的一个小例子

package com.today.car.filter;

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;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class UrlFilter implements Filter {

	public void destroy() {
	
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
	HttpServletRequest hrequest=(HttpServletRequest)request;
	HttpServletResponse hresponse=(HttpServletResponse)response;
     HttpSession session=hrequest.getSession();
     if(session.getAttribute("USER")==null&&"".equals(session.getAttribute("USER"))){
    	 hresponse.sendRedirect("index.jsp");
     }
     chain.doFilter(request, response);
     
	
	
	}

	public void init(FilterConfig filterConfig) throws ServletException {
	
	}

}