美文网首页
DelayQueue介绍及应用

DelayQueue介绍及应用

作者: 夏日橘子冰 | 来源:发表于2018-08-06 14:08 被阅读0次

    概念:

    DelayQueue是一个无界阻塞队列,用于放置实现了Delayed接口的对象,只有在延迟期满时才能从中提取元素。该队列时有序的,即队列的头部是延迟期满后保存时间最长的Delayed 元素。注意:不能将null元素放置到这种队列中。

    项目场景:店铺取票后五分钟内没有出票,即收回所取的票

    实现:

    step1 创建接口里需要放的对象类型,实现Delayed

    public class OrderInfoDelayBean extends OrderInfo implements Delayed {
    //必须实现Delayed接口,重写compareTo方法。该方法提供一个和getDelay方法一致的排序。即从队列里取过期元素的顺序即按照此顺序。
    
        private static final long serialVersionUID = 6255640460985141483L;
        
        private long dueTime;
    
        @Override
        public int compareTo(Delayed o) {
            final OrderInfoDelayBean other = (OrderInfoDelayBean) o;
            if (this.dueTime<other.dueTime) {
                return -1;
            } else if (this.getLastPrintDate().after(other.getLastPrintDate())) {
                return 1;
            }
            return 0;
        }
    
        @Override
        public long getDelay(TimeUnit unit) {
            return unit.convert(dueTime - new Date().getTime(), TimeUnit.NANOSECONDS);
        }
    
        public long getDueTime() {
            return dueTime;
        }
    
        public void setDueTime(long dueTime) {
            this.dueTime = dueTime;
        }
        
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (this.getClass() != obj.getClass()) {
                return false;
            }
            final OrderInfoDelayBean other = (OrderInfoDelayBean) obj;
            if (!this.getSerialNumber().equals(other.getSerialNumber())) {
                return false;
            }
            return true;
        }
    }
    
    step2

    执行任务的类里定义一个静态变量DelayQueue,每次店铺取票时,new一个delayBean,过期时间设置为当前时间加5min,将delayBean放入队列

    public class OrderInfoManager {
    
        private static Logger logger = Logger.getLogger(OrderInfoManager.class); 
        
        public static DelayQueue<OrderInfoDelayBean> DELAY_QUEUE = new DelayQueue<>();
        
        public static void addOrderInfoDelay(OrderInfoVo orderInfoVo){
            //转换成OrderInfoDelayBean再加入队列
            OrderInfoDelayBean orderInfoDelayBean = new OrderInfoDelayBean();
            try {
                BeanUtils.copyProperties(orderInfoDelayBean, orderInfoVo);
            } catch (Exception e) {
                logger.error("将订单加入队列时,copy出错");
                logger.error(e.getMessage(),e.fillInStackTrace());
            }
            orderInfoDelayBean.setDueTime(new Date().getTime()+300000);
            if(!DELAY_QUEUE.contains(orderInfoDelayBean)){
                DELAY_QUEUE.add(orderInfoDelayBean);
                logger.info("订单"+orderInfoDelayBean.getSerialNumber()+"进入延时队列,当前时间"+new Date().getTime());
            }
        }
    }
    
    
    step3

    写一个定时任务,while((orderInfoDelayBean=DELAY_QUEUE.take())!=null) {} 过期时会自动拿到,拿到后按照需求执行操作。拿不到时,take()方法会一直阻塞,所以虽然是定时任务,实际执行一次后就阻塞着不会再多次执行了

    public void deleteTimeUpOrderInfo() throws InterruptedException {
            logger.info("=-=-=-=-=-=-=-=-=-=-= 清除下派给散铺的过期订单开始");
            OrderInfoDelayBean orderInfoDelayBean = null;
            while((orderInfoDelayBean=DELAY_QUEUE.take())!=null) {
                logger.info("=-=-=-=-=-=-=-=-=-=-= 清除下派给散铺的过期订单【"+orderInfoDelayBean.getSerialNumber()+"】成功,当前时间"+new Date().getTime());
                //更新订单打印状态、店铺id、下发时间
                orderService.recallOrderFromStore(orderInfoDelayBean.getSerialNumber());
                //更新订单下的票打印状态、店铺id、下发时间
                ticketService.recallTicketFromStore(orderInfoDelayBean.getSerialNumber());
            }
        }
    
    

    相关配置:

    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
        xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
                http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
                http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"
        default-autowire="byName" default-lazy-init="true">
    
        <bean id="orderInfoManager" class="com.latech.order.manager.OrderInfoManager"></bean>
    
        <bean id="getOrderInfoFormDBTask" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
            <property name="targetObject">
                <ref bean="orderInfoManager" />
            </property>
            <property name="targetMethod">
                <value>getOrderInfoFormDB</value>
            </property>
            <property name="concurrent">
                <value>false</value>
            </property>
        </bean>
        
        <bean id="clearIssuedOrderInfoTask" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
            <property name="targetObject">
                <ref bean="orderInfoManager" />
            </property>
            <property name="targetMethod">
                <value>clearIssuedOrderInfo</value>
            </property>
            <property name="concurrent">
                <value>false</value>
            </property>
        </bean>
        
        <bean id="deleteTimeUpOrderInfoTask" class="org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean">
            <property name="targetObject">
                <ref bean="orderInfoManager" />
            </property>
            <property name="targetMethod">
                <value>deleteTimeUpOrderInfo</value>
            </property>
            <property name="concurrent">
                <value>false</value>
            </property>
        </bean>
        
        <!-- 调度触发器 -->
        <bean id="getOrderInfoFormDBDoTime" class="org.springframework.scheduling.quartz.SimpleTriggerFactoryBean">
            <property name="jobDetail">
                <ref bean="getOrderInfoFormDBTask" />
            </property>
            <property name="startDelay" value="0" />
            <property name="repeatInterval" value="5000" />
        </bean>
        <!-- 调度触发器 -->
        <bean id="clearIssuedOrderInfoDoTime" class="org.springframework.scheduling.quartz.SimpleTriggerFactoryBean">
            <property name="jobDetail">
                <ref bean="clearIssuedOrderInfoTask" />
            </property>
            <property name="startDelay" value="0" />
            <property name="repeatInterval" value="3000" />
        </bean>
        <!-- 调度触发器 -->
        <bean id="deleteTimeUpOrderInfoDoTime" class="org.springframework.scheduling.quartz.SimpleTriggerFactoryBean">
            <property name="jobDetail">
                <ref bean="deleteTimeUpOrderInfoTask" />
            </property>
            <property name="startDelay" value="0" />
            <property name="repeatInterval" value="100" />
        </bean>
        
        <bean autowire="no" class="org.springframework.scheduling.quartz.SchedulerFactoryBean">
            <property name="triggers">
                <list>
                    <ref bean="getOrderInfoFormDBDoTime" />
                    <ref bean="clearIssuedOrderInfoDoTime" />
                    <ref bean="deleteTimeUpOrderInfoDoTime" />
                </list>
            </property>
        </bean>
        
    </beans>    
    

    注意:
    此配置里除了deleteTimeUpOrderInfoTask任务,还有其它任务,此处特意把配置放上来,是因为这里有一个需要特别注意的问题

    • 使用注解@Schedule配置时,由于take()方法是阻塞的,影响到其它定时任务的执行
    • 给方法再加一个注解@Async,类加上@EnableAsync时,定时任务都可以执行了,但这里就有一个问题,take()变得不阻塞了
      所以最后采取xml如上配置实现

    相关文章

      网友评论

          本文标题:DelayQueue介绍及应用

          本文链接:https://www.haomeiwen.com/subject/pjawvftx.html