MQ初识篇

同步调用的优点：

• 时效性较强，可以立即得到结果

同步调用的缺点：

• 耦合度高

• 性能和吞吐能力下降

• 有额外的资源消耗

• 有级联失败问题

异步调用的优点：

• 吞吐量提升：无需等待订阅者处理完成，响应更快速

• 故障隔离：服务没有直接调用，不存在级联失败问题

• 调用间没有阻塞，不会造成无效的资源占用

• 耦合度极低，每个服务都可以灵活插拔，可替换

• 流量削峰：不管发布事件的流量波动多大，都由Broker接收，订阅者可以按照自己的速度去处理事件

异步调用的缺点：

• 架构复杂了，业务没有明显的流程线，不好管理

• 需要依赖于Broker的可靠、安全、性能

MQ是消息队列，用来存储JSON数据。

通过docker命令拉取

docker pull rabbitmq:3.8-management

执行下面的命令来运行MQ容器

docker run 
 -e RABBITMQ_DEFAULT_USER=xiaoming 
 -e RABBITMQ_DEFAULT_PASS=123456 
 -v mq-plugins:/plugins 
 --name mq 
 --hostname mq 
 -p 15672:15672 
 -p 5672:5672 
 -d 
 rabbitmq:3.8-management

官方的HelloWorld是基于最基础的消息队列模型来实现的，只包括三个角色：

• publisher：消息发布者，将消息发送到队列queue

• queue：消息队列，负责接受并缓存消息

• consumer：订阅队列，处理队列中的消息

      首先准备一个mq-demo父工程，子工程分别为publisher（消息的发送者），consumer（消息的消费者）。

consumer（消息消费者）子模块代码：

配置类：

@Configuration
public class FanoutConfig {
    // itcast.fanout
    @Bean
    public FanoutExchange fanoutExchange(){
        return new FanoutExchange("itcast.fanout");
    }

    // fanout.queue1
    @Bean
    public Queue fanoutQueue1(){
        return new Queue("fanout.queue1");
    }

    // 绑定队列1到交换机
    @Bean
    public Binding fanoutBinding1(Queue fanoutQueue1, FanoutExchange fanoutExchange){
        return BindingBuilder
                .bind(fanoutQueue1)
                .to(fanoutExchange);
    }

    // fanout.queue2
    @Bean
    public Queue fanoutQueue2(){
        return new Queue("fanout.queue2");
    }

    // 绑定队列2到交换机
    @Bean
    public Binding fanoutBinding2(Queue fanoutQueue2, FanoutExchange fanoutExchange){
        return BindingBuilder
                .bind(fanoutQueue2)
                .to(fanoutExchange);
    }

    @Bean
    public Queue objectQueue(){
        return new Queue("object.queue");
    }
}

监听器：

@Component
public class SpringRabbitListener {

    // @RabbitListener(queues = "simple.queue")
    // public void listenSimpleQueue(String msg) {
    //     System.out.println("消费者接收到simple.queue的消息：【" + msg + "】");
    // }

    @RabbitListener(queues = "simple.queue")
    public void listenWorkQueue1(String msg) throws InterruptedException {
        System.out.println("消费者1接收到消息：【" + msg + "】" + LocalTime.now());
        Thread.sleep(20);
    }

    @RabbitListener(queues = "simple.queue")
    public void listenWorkQueue2(String msg) throws InterruptedException {
        System.err.println("消费者2........接收到消息：【" + msg + "】" + LocalTime.now());
        Thread.sleep(200);
    }

    @RabbitListener(queues = "fanout.queue1")
    public void listenFanoutQueue1(String msg) {
        System.out.println("消费者接收到fanout.queue1的消息：【" + msg + "】");
    }
    @RabbitListener(queues = "fanout.queue2")
    public void listenFanoutQueue2(String msg) {
        System.out.println("消费者接收到fanout.queue2的消息：【" + msg + "】");
    }

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "direct.queue1"),
            exchange = @Exchange(name = "itcast.direct", type = ExchangeTypes.DIRECT),
            key = {"red", "blue"}
    ))
    public void listenDirectQueue1(String msg){
        System.out.println("消费者接收到direct.queue1的消息：【" + msg + "】");
    }

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "direct.queue2"),
            exchange = @Exchange(name = "itcast.direct", type = ExchangeTypes.DIRECT),
            key = {"red", "yellow"}
    ))
    public void listenDirectQueue2(String msg){
        System.out.println("消费者接收到direct.queue2的消息：【" + msg + "】");
    }

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "topic.queue1"),
            exchange = @Exchange(name = "itcast.topic", type = ExchangeTypes.TOPIC),
            key = "china.#"
    ))
    public void listenTopicQueue1(String msg){
        System.out.println("消费者接收到topic.queue1的消息：【" + msg + "】");
    }

    @RabbitListener(bindings = @QueueBinding(
            value = @Queue(name = "topic.queue2"),
            exchange = @Exchange(name = "itcast.topic", type = ExchangeTypes.TOPIC),
            key = "#.news"
    ))
    public void listenTopicQueue2(String msg){
        System.out.println("消费者接收到topic.queue2的消息：【" + msg + "】");
    }

    @RabbitListener(queues = "object.queue")
    public void listenObjectQueue(Map msg){
        System.out.println("接收到object.queue的消息：" + msg);
    }
}

启动类：

@SpringBootApplication
public class ConsumerApplication {
    public static void main(String[] args) {
        SpringApplication.run(ConsumerApplication.class, args);
    }
    @Bean
    public MessageConverter messageConverter(){
        return new Jackson2JsonMessageConverter();
    }
}

application.yml配置文件：

logging:
  pattern:
    dateformat: MM-dd HH:mm:ss:SSS
spring:
  rabbitmq:
    host: 192.168.150.101 # rabbitMQ的ip地址
    port: 5672 # 端口
    username: xiaoming
    password: 123456
    virtual-host: /
    listener:
      simple:
        prefetch: 1

pom依赖：

    
        mq-demo
        cn.itcast.demo
        1.0-SNAPSHOT
    
    4.0.0

    consumer

    
        8
        8
    

publisher（消息发送者）子模块代码：

配置类：

@SpringBootApplication
public class PublisherApplication {
    public static void main(String[] args) {
        SpringApplication.run(PublisherApplication.class);
    }

    @Bean
    public MessageConverter messageConverter(){
        return new Jackson2JsonMessageConverter();
    }
}

application.yml配置文件：

logging:
  pattern:
    dateformat: MM-dd HH:mm:ss:SSS
spring:
  rabbitmq:
    host: 192.168.150.101 # rabbitMQ的ip地址
    port: 5672 # 端口
    username: xiaoming
    password: 123456
    virtual-host: /

pom依赖：

    
        mq-demo
        cn.itcast.demo
        1.0-SNAPSHOT
    
    4.0.0

    publisher

    
        8
        8
    

父模块代码：

pom依赖：

    4.0.0

    cn.itcast.demo
    mq-demo
    1.0-SNAPSHOT
    
        publisher
        consumer
    
    pom

    
        org.springframework.boot
        spring-boot-starter-parent
        2.3.9.RELEASE
        
    

    
        8
        8
    

    
        
            org.projectlombok
            lombok
        
        
        
            org.springframework.boot
            spring-boot-starter-amqp
        
        
        
            org.springframework.boot
            spring-boot-starter-test
        
        
            com.fasterxml.jackson.core
            jackson-databind
        
    

public class PublisherTest {
    @Test
    public void testSendMessage() throws IOException, TimeoutException {
        // 1.建立连接
        ConnectionFactory factory = new ConnectionFactory();
        // 1.1.设置连接参数，分别是：主机名、端口号、vhost、用户名、密码
        factory.setHost("192.168.150.101");
        factory.setPort(5672);
        factory.setVirtualHost("/");
        factory.setUsername("itcast");
        factory.setPassword("123321");
        // 1.2.建立连接
        Connection connection = factory.newConnection();

        // 2.创建通道Channel
        Channel channel = connection.createChannel();

        // 3.创建队列
        String queueName = "simple.queue";
        channel.queueDeclare(queueName, false, false, false, null);

        // 4.发送消息
        String message = "hello, rabbitmq!";
        channel.basicPublish("", queueName, null, message.getBytes());
        System.out.println("发送消息成功：【" + message + "】");

        // 5.关闭通道和连接
        channel.close();
        connection.close();

    }
}

public class ConsumerTest {

    public static void main(String[] args) throws IOException, TimeoutException {
        // 1.建立连接
        ConnectionFactory factory = new ConnectionFactory();
        // 1.1.设置连接参数，分别是：主机名、端口号、vhost、用户名、密码
        factory.setHost("192.168.150.101");
        factory.setPort(5672);
        factory.setVirtualHost("/");
        factory.setUsername("itcast");
        factory.setPassword("123321");
        // 1.2.建立连接
        Connection connection = factory.newConnection();

        // 2.创建通道Channel
        Channel channel = connection.createChannel();

        // 3.创建队列
        String queueName = "simple.queue";
        channel.queueDeclare(queueName, false, false, false, null);

        // 4.订阅消息
        channel.basicConsume(queueName, true, new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope,
                                       AMQP.BasicProperties properties, byte[] body) throws IOException {
                // 5.处理消息
                String message = new String(body);
                System.out.println("接收到消息：【" + message + "】");
            }
        });
        System.out.println("等待接收消息。。。。");
    }
}