网上图书商城项目学习笔记-023前端登录过滤器实现

一、流程分析

二、代码

1.web.xml

<!-- 登录过滤(订单及购物车只有登录才能访问) -->
  <filter>
      <display-name>LoginFilter</display-name>
      <filter-name>LoginFilter</filter-name>
      <filter-class>com.tony.goods.web.servlet.LoginFilter</filter-class>
  </filter>
  <filter-mapping>
      <filter-name>LoginFilter</filter-name>
      <url-pattern>/jsps/cart/*</url-pattern>
  </filter-mapping>
  <filter-mapping>
      <filter-name>LoginFilter</filter-name>
      <servlet-name>CartItemServlet</servlet-name>
  </filter-mapping>
  <filter-mapping>
      <filter-name>LoginFilter</filter-name>
      <url-pattern>/jsps/order/*</url-pattern>
  </filter-mapping>
  <filter-mapping>
      <filter-name>LoginFilter</filter-name>
      <servlet-name>OrderServlet</servlet-name>
  </filter-mapping>

 

2.Filter

(1）LoginFilter.java

package com.tony.goods.web.servlet;

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;

public class LoginFilter implements Filter {

    @Override
    public void destroy() {
        
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        Object user = req.getSession().getAttribute("sessionUser");
        if(user == null) {
            req.setAttribute("code", "error");
            req.setAttribute("msg", "您还没有登录，不能访问本资源");
            req.getRequestDispatcher("/jsps/msg.jsp").forward(req, response);
        } else {
            chain.doFilter(request, response);
        }
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        
    }

}