一. RabbitMQ消息处理
在上一节我们讲到了RabbitMQ的简单架构，我们先回顾一下RabbitMQ中消息的流转流程，这个概念会在本节中使用到。
1.生产者生产消息后，会绑定一个路由键将消息投递到交换器中
2.队列通过路由键绑定到交换器
3.交换器通过消息的路由键去查找绑定在它上面的队列，通过不同的规则去匹配队列绑定的路由键，匹配成功后将消息路由到队列上，遍历所有队列后都没有匹配的消息将无法路由到队列
4.消费者监听队列，一旦有消息路由到队列，消费者就会从队列中取出消息或者是RabbitMQ将消息推送给消费者进行消费
上面的流程是在正常情况下的消息处理流程，对于投递失败的消息和消费失败的消息，我们会在后续的知识点中讲到
二. 交换器类型
不同类型的交换器有不同的路由键键匹配规则，我们先来看看RabbitMQ中有哪几种交换器
1 Direct
只有当路由键完全匹配时，才会将消息投递到相应的队列中
2 Fanout
消息广播到绑定的队列，即该类型的交换器不会根据路由键去匹配队列，只要有消息投递到该交换器，它就会将消息投递到所有绑定在该交换器上的队列
3 Topic
Topic交换器可以使用通配符("*" 和 "#")使来自不同源头的消息到达统一队列。”.”将路由键分为了几个标识符，" * "匹配1个，"#"匹配一个或多个
eg：有四个队列，queue1绑定路由键"usa.#"，queue2绑定路由键"#.news"，queue3绑定路由键"*.weather"，queue4绑定路由键"europe.*"
四条消息:message1绑定的路由键为"usa.news"，message2绑定的路由键为"usa.weather"，message3绑定的路由键为"europe.news"，message4绑定的路由键为"errope.weather"
路由后:
queue1能收到消息message1，message2
queue2能收到消息message1，message3
queue3能收到消息message2，message4
queue4能收到消息message3，message4
需要注意一点是，"*"是匹配一个，"#"匹配多个。若是消息绑定路由键为usa.weather.cloud，那么"usa.*"无法匹配该路由键，"usa.#"能匹配，此时也可以使用"usa.*.*"匹配
4 Headers
由于headers交换器基本不用，这里就不做讲解
三. 使用RabbitMQ原生API
使用RabbitMQ原生API来发送和消费消息时，按照如下流程
生产者：
获取连接工厂
ConnectionFactory factory = new ConnectionFactory();
新建连接
public Connection newConnection();
创建信道
Channel createChannel();
声明交换器
Exchange.DeclareOk exchangeDeclare(String exchange, BuiltinExchangeType type)
args1 交换器名称，args2交换器类型
发送消息
void basicPublish(String exchange, String routingKey, boolean mandatory, BasicProperties props, byte[] body)
args1 交换器名，args2 路由键，args3 消息无法路由时的处理，为true时生产者可以通过回调函数获取消息状态，args4 消息属性，args5 消息体
消费者:
获取连接工厂
ConnectionFactory factory = new ConnectionFactory();
新建连接
public Connection newConnection();
创建信道
Channel createChannel();
声明交换器
Exchange.DeclareOk exchangeDeclare(String exchange, BuiltinExchangeType type)
args1 交换器名称，args2交换器类型
声明队列
Queue.DeclareOk queueDeclare(String queue, boolean durable, boolean exclusive, boolean autoDelete, Map<String, Object> arguments)
args1 队列名，arg2 是否持久化，args3 是否独占队列，args4 自动删除，args5 其他属性
队列绑定
Queue.BindOk queueBind(String queue, String exchange, String routingKey, Map<String, Object> arguments)
args1 队列名，args2 交换器名，args3 路由键，arg4 其他属性
消息消费
String basicConsume(String queue, boolean autoAck, Consumer callback)
args1 队列名，args2 是否自动签收，args3 消费者
四. 使用不同的交换器完成消息处理
- Direct Exchange
DirectProducer Demo
public class DirectProducer {
public static final String EXCHANGE_NAME = "direct_exchange";
public static final String ROUTING_KEY = "direct_key";
public static void main(String[] args) throws Exception{
// 创建连接工厂
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("127.0.0.1");
factory.setVirtualHost("/");
// 新建连接
Connection connection = factory.newConnection();
// 创建信道
Channel channel = connection.createChannel();
// 声明交换器
channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.DIRECT);
String msg = "hello rabbitmq";
// 发送消息
channel.basicPublish(EXCHANGE_NAME, ROUTING_KEY,null, msg.getBytes());
System.out.println("消息投递完成，消息:" + msg + ", 路由键:" + ROUTING_KEY);
channel.close();
connection.close();
}
}生产者端结果
DirectConsumer Demo
public class DirectConsumer {
public static void main(String[] args) throws Exception{
// 创建连接工厂
ConnectionFactory connectionFactory = new ConnectionFactory();
connectionFactory.setHost("127.0.0.1");
connectionFactory.setVirtualHost("/");
// 创建连接
Connection connection = connectionFactory.newConnection();
// 创建信道
Channel channel = connection.createChannel();
// 声明交换器
channel.exchangeDeclare(DirectProducer.EXCHANGE_NAME, BuiltinExchangeType.DIRECT);
String queueName = "direct_queue";
// 声明队列
channel.queueDeclare(queueName, false, false, false, null);
// 将队列绑定到交换器
channel.queueBind(queueName, DirectProducer.EXCHANGE_NAME, DirectProducer.ROUTING_KEY);
// 声明消费者
Consumer consumer = new DefaultConsumer(channel){
@Override
public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
String msg = new String(body, "UTF-8");
System.out.println("收到的消息:" + msg + ", 路由键:" + envelope.getRoutingKey());
}
};
// 消费者消费指定队列的消息
channel.basicConsume(queueName, true, consumer);
}
}消费端结果：
- Fanout Exchange
FanoutProducer Demo
public class FanoutProducer {
// 交换器
public static final String EXCHANGE_NAME = "fanout_exchange";
// 路由键
public static final String ROUTING_KEY = "fanout_key";
public static void main(String[] args) throws Exception{
// 获取连接工厂
ConnectionFactory connectionFactory = new ConnectionFactory();
connectionFactory.setVirtualHost("/");
connectionFactory.setHost("127.0.0.1");
connectionFactory.setPort(5672);
// 获取连接
Connection connection = connectionFactory.newConnection();
// 声明信道
Channel channel = connection.createChannel();
// 声明交换器
channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.FANOUT);
// 发送消息
String msg = "hello rabbitmq";
channel.basicPublish(FanoutProducer.EXCHANGE_NAME, ROUTING_KEY, null, msg.getBytes());
System.out.println("发送消息:" + msg + "，路由键:" + ROUTING_KEY);
channel.close();
connection.close();
}
}生产端结果：
FanoutConsumer Demo
public class FanoutConsumer {
public static void main(String[] args) throws Exception{
// 创建连接工厂
ConnectionFactory connectionFactory = new ConnectionFactory();
connectionFactory.setHost("127.0.0.1");
connectionFactory.setVirtualHost("/");
// 创建连接
Connection connection = connectionFactory.newConnection();
// 创建信道
Channel channel = connection.createChannel();
// 声明交换器
channel.exchangeDeclare(FanoutProducer.EXCHANGE_NAME, BuiltinExchangeType.FANOUT);
// 队列
String[] queueNames = {"queue1", "queue2", "queue3"};
// 路由键
String[] routingKey = {"fanout_key", "fanout_key1", "fanout_key2"};
// 分别使用不同的路由键声明不同的队列
for (int i = 0; i < 3; i++){
channel.queueDeclare(queueNames[i], false, false, false, null);
channel.queueBind(queueNames[i], FanoutProducer.EXCHANGE_NAME, routingKey[i]);
// 消费消息
channel.basicConsume(queueNames[i], true, new DefaultConsumer(channel){
@Override
public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
String msg = new String(body, "UTF-8");
System.out.println("消息：" + msg + "，路由键：" + envelope.getRoutingKey());
}
});
}
}
}消费端结果：
- Topic Exchange
TopicProducer Demo
public class TopicProducer {
// 交换器
public static final String EXCHANGE_NAME = "topic_exchange";
public static void main(String[] args) throws Exception{
// 创建连接工厂
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("127.0.0.1");
factory.setVirtualHost("/");
// 新建连接
Connection connection = factory.newConnection();
// 创建信道
Channel channel = connection.createChannel();
// 声明交换器
channel.exchangeDeclare(TopicProducer.EXCHANGE_NAME, BuiltinExchangeType.TOPIC);
// 发送消息
String msg = "hello rabbitmq";
String[] routingKey = {"topic.key1", "topic.key2", "topic.key2.test"};
for (int i = 0; i < 3; i++){
channel.basicPublish(TopicProducer.EXCHANGE_NAME, routingKey[i], null, msg.getBytes());
System.out.println("发送消息:" + msg + ", 路由键:" + routingKey[i]);
}
channel.close();
connection.close();
}
}生产端结果：
TopicConsumer Demo
public class TopicConsumer {
public static void main(String[] args) throws Exception{
// 创建连接工厂
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("127.0.0.1");
factory.setVirtualHost("/");
// 新建连接
Connection connection = factory.newConnection();
// 创建信道
Channel channel = connection.createChannel();
// 声明交换器
channel.exchangeDeclare(TopicProducer.EXCHANGE_NAME, BuiltinExchangeType.TOPIC);
String queueName = "topic_queue";
// 声明队列
channel.queueDeclare(queueName, false, false, false, null);
// 队列绑定
channel.queueBind(queueName, TopicProducer.EXCHANGE_NAME, "topic.*");
// 消息消费
channel.basicConsume(queueName, true, new DefaultConsumer(channel){
@Override
public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
String msg = new String(body, "UTF-8");
System.out.println("消息:" + msg + ", 路由键:" + envelope.getRoutingKey());
}
});
}
}消费端结果：
java
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