springboot+thymeleaf+jquery和ajax+拦截器实现session状态保持

古城微笑少年丶 2022-05-27 03:27 259阅读 0赞

1.我的项目采用的是springboot框架和thymeleaf模板引擎，前端的逻辑控制用的是jquery，并用ajax进行异步请求

2.为了保持会话登录状态，我采用了拦截器来实现session判别

3.首先，定义我们自己的拦截器，这个拦截器要实现HandlerInterceptor接口，代码如下：

package server.demo.configure;
    
    import org.springframework.stereotype.Component;
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    import server.demo.entity.User;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    @Component
    public class MyInterceptor  implements HandlerInterceptor {
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
                throws Exception {
            //获取当前的session
            HttpSession session=request.getSession();
            //从session中寻求cur_user变量
            Object obj=session.getAttribute("cur_user");
            //判断是否存在用户变量
            //不存在则跳转到登录界面
            if(obj==null||!(obj instanceof User)){
              response.sendRedirect("/login");
             }else{
                //存在则再次注入session
                session.setAttribute("cur_user",(User)obj);
                System.out.println(((User) obj).getName()+((User) obj).getPassword());
            }
            return true;// 只有返回true才会继续向下执行，返回false取消当前请求
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
                               ModelAndView modelAndView) throws Exception {
    
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
                throws Exception {
    
        }
    }

4.然后，就要将拦截器进行注册，代码如下：

package server.demo.configure;
    
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
    import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
    
    import java.util.ArrayList;
    import java.util.List;
    
    @Configuration
    public class MyWebAppConfigurer extends WebMvcConfigurerAdapter {
        @Autowired
        MyInterceptor myInterceptor;
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
    
            // 多个拦截器组成一个拦截器链
            // addPathPatterns 用于添加拦截规则
            // excludePathPatterns 用户排除拦截
            List<String> list=new ArrayList<>();
            list.add("/myPub");
            list.add("/myRec");
            registry.addInterceptor(myInterceptor).addPathPatterns(list);
    
    
            super.addInterceptors(registry);
        }
    
    }

5.编写登录验证函数

@RequestMapping(value = "/check" ,method = RequestMethod.POST)
        @ResponseBody
        public  String check(@RequestBody JSONObject json  ){
            System.out.println("收到前端ajax请求");
                String name=json.getString("name");
                String password=json.getString("password");
                User user=new User();
                user.setName(name);
                user.setPassword(password);
                //向后台数据库查询用户id
                int id=userService.login(user);
                //如果id争取，则传回信息
                if(id>0){
                    //
                    user.setId(id);
                    session.setAttribute("cur_user",user);
                    System.out.println("传回正确信息");
                    return "1";
    
                }else{
                    System.out.println("传回错误信息");
                    return "0";
                }
        }

6.对应的ajax为:

7.这样每次访问页面，拦截器都会查看这些页面是否是注册要拦截的，如果是，就执行拦截器，也即是判断session中是否有用户的状态信息，如果有，则进行正确访问，如果没有，则跳转到登录页面让用户进行登录