Publish/Subscribe
**发布(Publish)、订阅(Subscribe)：**允许将同一个消息发送给多个消费者
**注意：**exchange负责消息路由，而不是存储，路由失败则消息丢失
常见的**X(exchange–交换机)***类型：
- Fanout 广播
- Direct 路由
- Topoc 话题
发布订阅–FanoutExchange
案例三：利用SpringAMQP演示广播交换机的使用
1.在消费者（consumer包）中，创建一个FanoutConfig类，声明队列、交换机，并将两者绑定
@Configuration
public class FanoutConfig {
//声明FanoutExchange交换机itcast.fanout
@Bean
public FanoutExchange fanoutExchange(){
return new FanoutExchange("itcast.fanout");
}
//声明fanout.queue1队列
@Bean
public Queue fanoutQueue1(){
return new Queue("fanout.queue1");
}
//绑定fanout.queue1队列和交换机
@Bean
public Binding bindingQueue1(Queue fanoutQueue1, FanoutExchange fanoutExchange){
return BindingBuilder.bind(fanoutQueue1).to(fanoutExchange);
}
//声明fanout.queue2队列
@Bean
public Queue fanoutQueue2(){
return new Queue("fanout.queue2");
}
//绑定fanout.queue2队列和交换机
@Bean
public Binding bindingQueue2(Queue fanoutQueue2, FanoutExchange fanoutExchange){
return BindingBuilder.bind(fanoutQueue2).to(fanoutExchange);
}
}
2.在消费者（consumer包）中，编写两个消费者SpringRabbitListener方法，分别监听fanout.queue1和fanout.queue2
@Component
public class SpringRabbitListener {
@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 + "】");
}
}
3.在publiSher中编写测试方法，向itcast.fanout发送消息
@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringAmqpTest {
@Autowired
private RabbitTemplate rabbitTemplate;
@Test
public void testSendFanoutExchange() {
// 交换机名称
String exchangeName = "itcast.fanout";
// 消息
String message = "hello, every one!";
// 发送消息
rabbitTemplate.convertAndSend(exchangeName, "", message);
}
}
4.运行，结果
发布订阅–DirectExchange
将接收到的消息根据规则路由到指定的Queue，因此称为路由模式(routes)
- 每一个Queue都与Exchange设置一个BindingKey（暗号）
- 发布者发送消息时，指定消息的RoutingKey
- Exchange将消息路由到BindingKey与消息RoutingKey一致的队列
案例四：利用SpringAMQP演示DirectExchange的使用
1.直接用注解
@RabbitListener声明Exchange、Queue、RoutingKey
@QueueBinding注解用于绑定队列和交换器，并指定路由键
@Component
public class SpringRabbitListener {
@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 + "】");
}
}
2.测试
@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringAmqpTest {
@Autowired
private RabbitTemplate rabbitTemplate;
@Test
public void testSendDirectExchange() {
// 交换机名称
String exchangeName = "itcast.direct";
// 消息
String message = "hello, red!";
// 发送消息
rabbitTemplate.convertAndSend(exchangeName, "red", message);
}
}
3.结果
发布订阅–TopicExchange
TopicExchange与DirectExchange类似，区别在于routingKey必须是多个单词的列表，并且以**.**分割
Queue与Exchange指定BindingKey时可以使用通配符
#: 代指0个或多个单词*: 代指一个单词
案例五：利用SpringAMQP演示TopicExchange的使用
1.直接用注解
@RabbitListener声明Exchange、Queue、RoutingKey
@QueueBinding注解用于绑定队列和交换器，并指定路由键
@Component
public class SpringRabbitListener {
@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 + "】");
}
}
2.测试
@RunWith(SpringRunner.class)
@SpringBootTest
public class SpringAmqpTest {
@Autowired
private RabbitTemplate rabbitTemplate;
@Test
public void testSendTopicExchange() {
// 交换机名称
String exchangeName = "itcast.topic";
// 消息
String message = "合理小姐是凑巧先生独一无二的女主角";
//String message = "今天天气不错，我的心情好极了!";
// 发送消息
rabbitTemplate.convertAndSend(exchangeName, "china.news", message);
//rabbitTemplate.convertAndSend(exchangeName, "china.weather", message);
}
}
3.结果
