自定义注解的实现

1.AOP实现场景 https://zhuanlan.zhihu.com/p/96597358

2.拦截器使用场景[SpringBoot之HandlerInterceptor拦截器]：

　通常是权限注解做一些预处理

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Inherited
public @interface TESTPermit {

    PermitEnum[] values() default {PermitEnum.COMMON};
}

---------------------

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Arrays;
import java.util.List;

/**
 * 请求拦截.
 */
@Slf4j
public class TESTPermitInterceptor implements HandlerInterceptor {

    // 在业务处理器处理请求之前被调用
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //优化.
        String token = request.getHeader(JwtSecurityDefines.HEADER_AUTHORIZATION);
        Integer platId = 0;

        //但凡能进入本拦截器的，没token的说明在白名单里，直接放行
        if(StringUtil.isNotEmpty(token)){
            try {
                platId = JwtUtil.***(token);
            } catch (Exception ex) {
                throw new ****("无权限");
            }
        }else{
            return true;
        }

        if (handler instanceof HandlerMethod) {
            HandlerMethod handlerMethod = (HandlerMethod) handler;
            if (handlerMethod.hasMethodAnnotation(ATGPermit.class)) {
                PermitEnum[] permitEnums = handlerMethod.getMethodAnnotation(ATGPermit.class).values();
                List<PermitEnum> permitList = Arrays.asList(permitEnums);
                if (permitList.contains(PermitEnum.COMMON)) {
                    return true;
                }
                if ((platId == * && permitList.contains(PermitEnum.DMP)) 
                        || (platId == * && permitList.contains(PermitEnum.PSP))) { 
                    return true;
                } else {
                    return false;
                }
            } else {
                return true;
            }
        } else {
            return true;
        }
    }

    // 在业务处理器处理请求完成之后，生成视图之前执行
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
            throws Exception {
    }

    // 在DispatcherServlet完全处理完请求之后被调用，可用于清理资源
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
    }

}