Filter实现登录功能限制

public void doFilter(ServletRequest arg0,ServletResponse arg1,FilterChain chain) throws IOException, ServletException{
		HttpServletRequest req=(HttpServletRequest)arg0;
		HttpServletResponse resp=(HttpServletResponse)arg1;
		
		Object user=req.getSession().getAttribute("user");
		
		String uri=req.getRequestURI();
		String url=req.getRequestURL().toString();
		System.out.println("SecurityFilter  uei=========="+uri);
		System.out.println("SecurityFilter  url++++++++++"+url);
		
//		用户想要进入登录页面和用户需要提交的登录数据
		if("/test/hello.jsp".equals(uri)||"/test/my".equals(uri)){
//			用户在提交登录的信息
			chain.doFilter(arg0, arg1);
		}else if(user==null){
//			没有登录
			resp.sendRedirect("hello.jsp");
		}else{
//			登录了系统，可以访问
			chain.doFilter(arg0, arg1);
		}
	}