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2 使用RabbitMQ实现消息队列

2.1 修改\hm-dianping\pom.xmlpom.xml文件

添加RabbitMQ的环境

<!-- RabbitMQ-->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-amqp</artifactId>
</dependency>

2.2 修改Resource下的application.yaml文件

添加RabbitMQ的配置信息

spring:rabbitmq:host: 127.0.0.1 # IP地址port: 5672 # 端口号username: hmdianping # 用户名password: 123456 # 密码listener:simple:concurrency: 1max-concurrency: 1acknowledge-mode: manualprefetch: 1

主启动类标注@EnableRabbit开启消息队列的监听功能

2.3 配置RabbitMQ,创建交换机和消息队列，将二者绑定

创建direct类型的交换机以及一个名为seckill.order.queue的消息队列，然后将二者绑定.之后发往该交换机且路由键为seckill.order的消息都会转发seckill.order.queue

具体而言，在hm-dianping.src.main.java.com.hmdp.config下新建RabbitMQConfig文件

文件内容如下

package com.hmdp.config;import com.hmdp.entity.VoucherOrder;
import com.hmdp.service.IVoucherOrderService;
import com.rabbitmq.client.Channel;
import org.springframework.amqp.core.ExchangeTypes;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.Exchange;
import org.springframework.amqp.rabbit.annotation.Queue;
import org.springframework.amqp.rabbit.annotation.QueueBinding;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.amqp.support.converter.MessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import javax.annotation.Resource;
import java.io.IOException;@Configuration
public class RabbitMQConfig {@ResourceIVoucherOrderService voucherOrderService;@RabbitListener(bindings = @QueueBinding(value = @Queue(name = "direct.seckill.queue"),key = "direct.seckill",exchange = @Exchange(name = "hmdianping.direct", type = ExchangeTypes.DIRECT)))public void recieveMessage(Object message){System.out.println("监听到了"+message);}@Beanpublic MessageConverter messageConverter() {return new Jackson2JsonMessageConverter();}
}

2.3.1 测试监听消息

在Test中添加发送消息的方法，指定交换机hmdianping.direct 为和路由键 direct.seckill。

    @ResourceRabbitTemplate rabbitTemplate;@Testpublic void testSendMessage(){rabbitTemplate.convertAndSend("hmdianping.direct","direct.seckill","测试发送消息");}

先运行Test方法

之后运行启动类HmDianPingApplication

发现监听到了，说明连接成功。

2.3.2 修改秒杀下单业务(VoucherOrderServiceImpl中的seckillVoucher方法)

• 注入RabbitTemplate类

• 在认定有抢购资格后，直接向seckill.direct交换机发送消息，内容包含voucherId、userId、orderId

    @ResourceRabbitTemplate rabbitTemplate;@Overridepublic Result seckillVoucher(Long voucherId) {//1.执行lua脚本，判断当前用户的购买资格Long userId = UserHolder.getUser().getId();Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,Collections.emptyList(),voucherId.toString(), userId.toString());if (result != 0) {//2.不为0说明没有购买资格return Result.fail(result==1?"库存不足":"不能重复下单");}//3.走到这一步说明有购买资格，将订单信息存到消息队列VoucherOrder voucherOrder = new VoucherOrder();long orderId = redisIdWorker.nextId("order");voucherOrder.setId(orderId);voucherOrder.setUserId(UserHolder.getUser().getId());voucherOrder.setVoucherId(voucherId);//存入消息队列等待异步消费rabbitTemplate.convertAndSend("hmdianping.direct","direct.seckill",voucherOrder);return Result.ok(orderId);}

此时VoucherOrderServiceImpl文件内容如下

package com.hmdp.service.impl;import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.*;
import org.springframework.amqp.rabbit.core.RabbitTemplate;/*** <p>*  服务实现类* </p>** @author 虎哥* @since 2021-12-22*/
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {@Resourceprivate ISeckillVoucherService seckillVoucherService;@Resourceprivate IVoucherOrderService iVoucherOrderService;@Resourceprivate RedisIdWorker redisIdWorker;@Resourceprivate StringRedisTemplate stringRedisTemplate;@Resourceprivate RedissonClient redissonClient;private static final DefaultRedisScript<Long> SECKILL_SCRIPT;static {SECKILL_SCRIPT = new DefaultRedisScript<>();SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));SECKILL_SCRIPT.setResultType(Long.class);}private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);//异步处理线程池private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();@Transactionalpublic void handleVoucherOrder(VoucherOrder voucherOrder) {//1.所有信息从当前消息实体中拿Long voucherId = voucherOrder.getVoucherId();//2.扣减库存boolean success = seckillVoucherService.update().setSql("stock=stock-1").eq("voucher_id", voucherId)//======判断当前库存是否大于0就可以决定是否能抢池子中的券了.gt("stock", 0).update();//3.创建订单if(success) save(voucherOrder);}@ResourceRabbitTemplate rabbitTemplate;@Overridepublic Result seckillVoucher(Long voucherId) {//1.执行lua脚本，判断当前用户的购买资格Long userId = UserHolder.getUser().getId();Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,Collections.emptyList(),voucherId.toString(), userId.toString());if (result != 0) {//2.不为0说明没有购买资格return Result.fail(result==1?"库存不足":"不能重复下单");}//3.走到这一步说明有购买资格，将订单信息存到消息队列VoucherOrder voucherOrder = new VoucherOrder();long orderId = redisIdWorker.nextId("order");voucherOrder.setId(orderId);voucherOrder.setUserId(UserHolder.getUser().getId());voucherOrder.setVoucherId(voucherId);//存入消息队列等待异步消费rabbitTemplate.convertAndSend("hmdianping.direct","direct.seckill",voucherOrder);return Result.ok(orderId);}@Transactionalpublic void createVoucherOrder(VoucherOrder voucherOrder){// 5.一人一单逻辑// 5.1.用户idLong userId = voucherOrder.getId();int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder).count();// 5.2.判断是否存在if (count > 0) {// 用户已经购买过了log.error("用户已经购买过一次！");return ;}//6.扣减库存boolean success = seckillVoucherService.update().setSql("stock= stock -1") // set stock = stock -1.eq("voucher_id", voucherOrder).gt("stock",0)// where id = ? and stock > 0.update();if (!success) {//扣减库存log.error("库存不足！");return ;}save(voucherOrder);}
}

2.3.3 监听秒杀成功订单

• 监听seckill.order.queue队列的信息并且创建订单到数据库，当创建完成时手动ack

RabbitMQConfig中的recieveMessage修改为

    public void recieveMessage(Message message, Channel channel, VoucherOrder voucherOrder){try {voucherOrderService.handleVoucherOrder(voucherOrder);channel.basicAck(message.getMessageProperties().getDeliveryTag(), false);} catch (IOException e) {throw new RuntimeException(e);}System.out.println("监听到了"+message);}

此时，文件内容为。

package com.hmdp.config;import com.hmdp.entity.VoucherOrder;
import com.hmdp.service.IVoucherOrderService;
import com.rabbitmq.client.Channel;
import org.springframework.amqp.core.ExchangeTypes;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.Exchange;
import org.springframework.amqp.rabbit.annotation.Queue;
import org.springframework.amqp.rabbit.annotation.QueueBinding;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.amqp.support.converter.MessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;import javax.annotation.Resource;
import java.io.IOException;@Configuration
public class RabbitMQConfig {@ResourceIVoucherOrderService voucherOrderService;@RabbitListener(bindings = @QueueBinding(value = @Queue(name = "direct.seckill.queue"),key = "direct.seckill",exchange = @Exchange(name = "hmdianping.direct", type = ExchangeTypes.DIRECT)))
/*    public void recieveMessage(Object message){System.out.println("监听到了"+message);}*/public void recieveMessage(Message message, Channel channel, VoucherOrder voucherOrder){try {voucherOrderService.handleVoucherOrder(voucherOrder);channel.basicAck(message.getMessageProperties().getDeliveryTag(), false);} catch (IOException e) {throw new RuntimeException(e);}System.out.println("监听到了"+message);}@Beanpublic MessageConverter messageConverter() {return new Jackson2JsonMessageConverter();}
}

2.3.4 测试

使用Apifox测试

成功