java实现队列和交换机的声明
在之前我们都是基于RabbitMQ控制台来创建队列、交换机。但是在实际开发时，队列和交换机是程序员定义的，将来项目上线，又要交给运维去创建。那么程序员就需要把程序中运行的所有队列和交换机都写下来，交给运维。在这个过程中是很容易出现错误的。
因此推荐的做法是由程序启动时检查队列和交换机是否存在，如果不存在自动创建。
3.8.1.基本API
SpringAMQP提供了一个Queue类，用来创建队列：
SpringAMQP还提供了一个Exchange接口，来表示所有不同类型的交换机：
我们可以自己创建队列和交换机，不过SpringAMQP还提供了ExchangeBuilder来简化这个过程：
而在绑定队列和交换机时，则需要使用BindingBuilder来创建Binding对象：
3.8.2.fanout示例(基于Bean声明)
在consumer中创建一个类，声明队列和交换机：
package com.itheima.consumer.config;import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.FanoutExchange;
import org.springframework.amqp.core.Queue;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class FanoutConfig {/*** 声明交换机* @return Fanout类型交换机*/@Beanpublic FanoutExchange fanoutExchange(){return new FanoutExchange("hmall.fanout");}/*** 第1个队列*/@Beanpublic Queue fanoutQueue1(){return new Queue("fanout.queue1");}/*** 绑定队列和交换机*/@Beanpublic Binding bindingQueue1(Queue fanoutQueue1, FanoutExchange fanoutExchange){return BindingBuilder.bind(fanoutQueue1).to(fanoutExchange);}/*** 第2个队列*/@Beanpublic Queue fanoutQueue2(){return new Queue("fanout.queue2");}/*** 绑定队列和交换机*/@Beanpublic Binding bindingQueue2(Queue fanoutQueue2, FanoutExchange fanoutExchange){return BindingBuilder.bind(fanoutQueue2).to(fanoutExchange);}
}
实际测试：
package com.itheima.consumer.config;import org.springframework.amqp.core.*;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class FanoutConfiguration {/*** 声明fanout类型交换机* @return*/@Beanpublic FanoutExchange fanoutExchange(){// 两种声明方法都可以// return ExchangeBuilder.fanoutExchange("hmall.fanout2").build();return new FanoutExchange("hmall.fanout2");}/*** 声明默认持久化的fanout.queue3队列* @return*/@Beanpublic Queue fanoutQueue3(){// 两种声明方法都可以// return QueueBuilder.durable("fanout.queue3").build();return new Queue("fanout.queue3");}/*** 绑定队列和交换机* @param fanoutExchange* @param fanoutQueue3* @return*/@Beanpublic Binding fanoutBinding3(FanoutExchange fanoutExchange,Queue fanoutQueue3){return BindingBuilder.bind(fanoutQueue3).to(fanoutExchange);}/*** 声明默认持久化的fanout.queue4队列* @return*/@Beanpublic Queue fanoutQueue4(){// 两种声明方法都可以return QueueBuilder.durable("fanout.queue4").build();
// return new Queue("fanout.queue4");}/*** 绑定队列和交换机* @return*/@Beanpublic Binding fanoutBinding4(){return BindingBuilder.bind(fanoutQueue4()).to(fanoutExchange());}
}3.8.2.direct示例(基于Bean声明)
direct模式由于要绑定多个KEY，会非常麻烦，每一个Key都要编写一个binding：
package com.itheima.consumer.config;import org.springframework.amqp.core.*;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class DirectConfig {/*** 声明交换机* @return Direct类型交换机*/@Beanpublic DirectExchange directExchange(){return ExchangeBuilder.directExchange("hmall.direct").build();}/*** 第1个队列*/@Beanpublic Queue directQueue1(){return new Queue("direct.queue1");}/*** 绑定队列和交换机*/@Beanpublic Binding bindingQueue1WithRed(Queue directQueue1, DirectExchange directExchange){return BindingBuilder.bind(directQueue1).to(directExchange).with("red");}/*** 绑定队列和交换机*/@Beanpublic Binding bindingQueue1WithBlue(Queue directQueue1, DirectExchange directExchange){return BindingBuilder.bind(directQueue1).to(directExchange).with("blue");}/*** 第2个队列*/@Beanpublic Queue directQueue2(){return new Queue("direct.queue2");}/*** 绑定队列和交换机*/@Beanpublic Binding bindingQueue2WithRed(Queue directQueue2, DirectExchange directExchange){return BindingBuilder.bind(directQueue2).to(directExchange).with("red");}/*** 绑定队列和交换机*/@Beanpublic Binding bindingQueue2WithYellow(Queue directQueue2, DirectExchange directExchange){return BindingBuilder.bind(directQueue2).to(directExchange).with("yellow");}
}3.8.4.基于注解声明
基于@Bean的方式声明队列和交换机比较麻烦，Spring还提供了基于注解方式来声明。
注意声明的文件是Listener下的，在监听者位置声明
例如，我们同样声明Direct模式的交换机和队列：
@RabbitListener(bindings = @QueueBinding(value = @Queue(name = "direct.queue1"),exchange = @Exchange(name = "hmall.direct", type = ExchangeTypes.DIRECT),key = {"red", "blue"}
))
public void listenDirectQueue1(String msg){System.out.println("消费者1接收到direct.queue1的消息：【" + msg + "】");
}@RabbitListener(bindings = @QueueBinding(value = @Queue(name = "direct.queue2"),exchange = @Exchange(name = "hmall.direct", type = ExchangeTypes.DIRECT),key = {"red", "yellow"}
))
public void listenDirectQueue2(String msg){System.out.println("消费者2接收到direct.queue2的消息：【" + msg + "】");
}
是不是简单多了。
再试试Topic模式：
@RabbitListener(bindings = @QueueBinding(value = @Queue(name = "topic.queue1"),exchange = @Exchange(name = "hmall.topic", type = ExchangeTypes.TOPIC),key = "china.#"
))
public void listenTopicQueue1(String msg){System.out.println("消费者1接收到topic.queue1的消息：【" + msg + "】");
}@RabbitListener(bindings = @QueueBinding(value = @Queue(name = "topic.queue2"),exchange = @Exchange(name = "hmall.topic", type = ExchangeTypes.TOPIC),key = "#.news"
))
public void listenTopicQueue2(String msg){System.out.println("消费者2接收到topic.queue2的消息：【" + msg + "】");
}
小结
