springboot自定义注解和aop程序锁及获取注解内的值

1.springboot自定义注解@

import java.lang.annotation.*; 
@Target({ElementType.PARAMETER, ElementType.METHOD})    
@Retention(RetentionPolicy.RUNTIME)    
@Documented    
public  @interface Servicelock { 
 	String description()  default "";
}

标记文本
讲解：description()是获取注解括号内的值的方法

2.aop程序锁及获取注解内的值

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.context.annotation.Scope;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Component
@Scope
@Aspect
@Order(1)
//order越小越是最先执行，但更重要的是最先执行的最后结束。order默认值是2147483647
public class LockAspect {
	/**
     * 思考：为什么不用synchronized
     * service 默认是单例的，并发下lock只有一个实例
     */
	private static  Lock lock = new ReentrantLock(true);//互斥锁 参数默认false，不公平锁  
	
	//Service层切点     用于记录错误日志
	@Pointcut("@annotation(com.itstyle.seckill.common.aop.Servicelock)")  
	public void lockAspect() {
		
	}
	
    @Around("lockAspect()")
    public  Object around(ProceedingJoinPoint joinPoint) { 
    	lock.lock();
    	Object obj = null;
		try {
			obj = joinPoint.proceed();
		} catch (Throwable e) {
			e.printStackTrace();
			throw new RuntimeException();       
		} finally{
			lock.unlock();
		}
    	return obj;
    } 
}

标记文本 joinPoint获取当前方法，在根据注解名获取

	MethodSignature signature = (MethodSignature) joinPoint.getSignature();
	Method method = signature.getMethod();
	ServiceLimit annotation = method.getAnnotation(ServiceLimit.class);
	String s = annotation.description();//获取注解内的的值s

3.拦截器获取@的值

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import java.io.PrintWriter;

@Slf4j
@Component
public class PermissionInterceptor implements HandlerInterceptor {


  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
  
    if (handler instanceof HandlerMethod) {
    
      HandlerMethod handlerMethod = (HandlerMethod) handler;
      //获取注解操作对象（如果对象为空说明该方法上没有目标驻俄籍）
      // Servicelock.class： Servicelock 为目标注解名类
     T ana = handlerMethod.getMethodAnnotation( Servicelock.class);
      if (ana != null) {
        return ana;
      }
		//核心代码
      Class clazz = handlerMethod.getBeanType();
      return (T) clazz.getAnnotation(annotation);
    }
    
    return HandlerInterceptor.super.preHandle(request, response, handler);
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
      ModelAndView modelAndView) throws Exception {
    HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
  }

  @Override
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
      throws Exception {
    HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
  }
}