面向切面@Aspect

package com.imooc.demo.filter;

import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;

import java.lang.annotation.*;

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
@Documented
@Order(Ordered.HIGHEST_PRECEDENCE)
public @interface LoginFilter {
}

package com.imooc.demo.filter;

import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.security.auth.login.LoginException;
import javax.servlet.http.HttpServletRequest;

@Aspect
@Slf4j
public class LoginFilterAspect {

    //自定义切入点
    @Pointcut("@annotation(com.imooc.demo.filter.LoginFilter)")
    private void allMethod(){}

    @Before("allMethod()")
    public Object exec(JoinPoint joinPoint) throws Throwable{

        try{
            Object[] args = joinPoint.getArgs();
            HttpServletRequest request = null;
            for (int i = 0; i < args.length; i++) {
                if (args[i] instanceof HttpServletRequest){
                    request = (HttpServletRequest) args[i];
                    break;
                }
            }
            if (null==request){
                RequestAttributes ra = RequestContextHolder.getRequestAttributes();
                ServletRequestAttributes sra = (ServletRequestAttributes) ra;
                request = sra.getRequest();
            }

            //获取用户登录信息
            Object user = request.getSession().getAttribute("user");

            if (null == user){
                log.info("用户未登录。");
               return new LoginException();
            }
        }catch (Exception ex){
            throw ex;
        }
        return null;
    }

}

后续在方法上加上@LoginFilter注解，即可是实现登录验证