一,为什么要使用消息队列实现删除购物车商品功能?
消息队列主要用来处理不需要立刻返回结果的业务,
常见的例子:
用户在下单后,要清除原购物车中的商品,
这个处理过程不需要马上实现也不需要返回结果给用户,
所以就适合使用队列来实现
作者:刘宏缔
二,演示项目的相关信息
1,项目地址
https://github.com/liuhongdi/mqcart
2,项目功能说明:
演示了用rocketmq实现消息的发送和接收
3, 项目结构:如图:
三,配置文件说明
1,send/pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.apache.rocketmq</groupId>
<artifactId>rocketmq-client</artifactId>
<version>4.7.1</version>
</dependency>
<!--fastjson begin-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.73</version>
</dependency>
2,receive/pom.xml
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.apache.rocketmq</groupId>
<artifactId>rocketmq-client</artifactId>
<version>4.7.1</version>
</dependency>
<!--fastjson begin-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.73</version>
</dependency>
说明:两个模块的pom.xml内容相同
3,receive/application.properties
server.port=8081
说明:两个模块同时运行时,需要把端口区分开,
send不做修改,使用默认的8080端口
receive这里指定使用8081端口
四,java代码说明
1,send/HomeController.java
@RestController
@RequestMapping("/home")
public class HomeController {
@Autowired
private Producer producer;
//初始化并发送消息
@RequestMapping("/send")
public String send() throws Exception {
//要删除的购物车的id
List<Integer> cartList = new ArrayList<Integer>();
cartList.add(1);
cartList.add(2);
cartList.add(3);
//消息
CartMsg msg = new CartMsg();
msg.setUserId(1);
msg.setCartList(cartList);
String msgJson = JSON.toJSONString(msg);
//生成一个信息,标签在这里手动指定
Message message = new Message(RocketConstants.TOPIC, "carttag", msgJson.getBytes());
//发送信息
SendResult sendResult = producer.getProducer().send(message);
System.out.println("生产者已发送一条信息,内容={"+sendResult+"}");
return "success";
}
}
2,send/CartMsg.java
//购物车消息
public class CartMsg {
//用户id
private int userId;
public int getUserId() {
return this.userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
//购物车id
private List<Integer> cartList;
public List<Integer> getCartList() {
return this.cartList;
}
public void setCartList(List<Integer> cartList) {
this.cartList = cartList;
}
}
发送的消息体,
两个模块中的的CartMsg.java文件相同
3,send/RocketConstants.java
public class RocketConstants {
//name server,有多个时用分号隔开
public static final String NAME_SERVER = "127.0.0.1:9876";
//topic的名字,应该从服务端先创建好,否则会报错
public static final String TOPIC = "laoliutest";
}
配置name server和topic,
两个模块中的的RocketConstants.java文件相同
4,send/Producer.java
//消息生产者类
@Component
public class Producer {
private String producerGroup = "cart_producer";
private DefaultMQProducer producer;
//构造
public Producer(){
//创建生产者
producer = new DefaultMQProducer(producerGroup);
//不开启vip通道
producer.setVipChannelEnabled(false);
//设定 name server
producer.setNamesrvAddr(RocketConstants.NAME_SERVER);
start();
}
//使producer启动
public void start(){
try {
this.producer.start();
} catch (MQClientException e) {
e.printStackTrace();
}
}
//返回producer
public DefaultMQProducer getProducer(){
return this.producer;
}
//进行关闭的方法
public void shutdown(){
this.producer.shutdown();
}
}
5,receive/Consumer.java
@Component
public class Consumer {
//消费者实体对象
private DefaultMQPushConsumer consumer;
//消费者组
public static final String CONSUMER_GROUP = "cart_consumer";
//构造函数 用来实例化对象
public Consumer() throws MQClientException {
consumer = new DefaultMQPushConsumer(CONSUMER_GROUP);
consumer.setNamesrvAddr(RocketConstants.NAME_SERVER);
//指定消费模式
consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_LAST_OFFSET);
//指定订阅主题
//指定订阅标签,*代表所有标签
consumer.subscribe(RocketConstants.TOPIC, "*");
//注册一个消费消息的Listener
//对消息的消费在这里实现
consumer.registerMessageListener((MessageListenerConcurrently) (msgs, context) -> {
//遍历接收到的消息
try {
for (Message msg : msgs) {
//得到消息的body
String body = new String(msg.getBody(), "utf-8");
//用json转成对象
CartMsg msgOne = JSON.parseObject(body, CartMsg.class);
//打印用户id
System.out.println(msgOne.getUserId());
//打印消息内容
System.out.println("消费者已接收到消息-topic={"+msg.getTopic()+"}, 消息内空={"+body+"}");
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
return ConsumeConcurrentlyStatus.RECONSUME_LATER;
}
return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
});
consumer.start();
System.out.println("消费者 启动成功=======");
}
}
这个是消息的消费者
6,其他消息的非关键代码可访问github
五,演示效果
1,访问send模块的controller:
http://127.0.0.1:8080/home/send
显示发送成功:
success
查看控制台:
生产者已发送一条信息,内容={SendResult [sendStatus=SEND_OK, msgId=C0A803D5113442A57993512ADA8E0000,
offsetMsgId=7F00000100002A9F0000000000003AE8, messageQueue=MessageQueue [topic=laoliutest, brokerName=broker-a, queueId=3], queueOffset=0]}
2,查看receive模块的控制台:
1
消费者已接收到消息-topic={laoliutest}, 消息内容={{"cartList":[1,2,3],"userId":1}
收到了消息,消息内容可解析
六,查看spring boot版本:
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.3.3.RELEASE)