web

过滤器

• 获取到session对象

    HttpServletRequest request=(HttpServletRequest)arg0;
    HttpServletResponse response=(HttpServletResponse)arg1;
    HttpSession session=request.getSession();
  

• 过滤器的使用:

  1. 使用过滤器检测用户是否登录
  2. 针对所有post请求,统一解决乱码问题

• 步骤:

  1. 在web.xml中设置相关的配置(类似与servlet的设置)
     

  2. 创建相关的过滤器类

  3. 实现过滤器接口(Filter)

  4. 重写相关方法()

      public class LoginFilter implements Filter {
     
      @Override
      public void destroy() {
     
      }
      /**
       * 核心过滤的方法
       */
      @Override
      public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)throws IOException, ServletException {
      	System.out.println("开始过滤");
      	//检测用户是否登录过(验证session)
      	HttpServletRequest request=(HttpServletRequest)arg0;
      	HttpServletResponse response=(HttpServletResponse)arg1;
      	HttpSession session=request.getSession();
      	//从session中获取用户信息
      	User user=(User)session.getAttribute("user");
      	if(user!=null && user.getName()!=null) {
      		System.out.println("开始放行");
      		//放行
      		arg2.doFilter(request, response);
      	}else {
      		System.out.println("拦截");
      		response.sendRedirect("/web10/login.jsp");
      	}
     
      }
     
      @Override
      public void init(FilterConfig arg0) throws ServletException {
     

  }

}