常用交换机
发布订阅（Publish/Subscribe）交换机
一个生产者给多个队列发送消息，X 代表交换机。
交换机的作用：类似网络路由器，主要提供转发功能，解决怎么把消息转发到不同的队列中，让消费者从不同队列取然后消费。
绑定：交换机和队列关联起来
发布订阅交换机，队列进行持久化，生产者发布消息，所有消费者都能接收到消息。
生产者代码
java
public class FanoutProducer{
private static final String EXCHANGE_NAME = "fanout_exchange";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
try (Connection connection = factory.newConnection();
Channel channel = connection.createChannel()) {
//创建交换机，参数：交换机名称，交换机类型
channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
Scanner scanner = new Scanner(System.in);
while(scanner.hasNext()){
String message = scanner.nextLine();
//第二个参数是路由规则
channel.basicPublish(EXCHANGE_NAME, "", null, message.getBytes("UTF-8"));
System.out.println(" [x] Sent '" + message + "'");
}
}
}
}消费者代码
java
public class FanoutConsumer {
private static final String EXCHANGE_NAME = "fanout_exchange";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
//绑定交换机，以及设置绑定规则
channel.exchangeDeclare(EXCHANGE_NAME, "fanout");
String queueName1 = "xiaowang";
String queueName2 = "xiaoli";
channel.queueDeclare(queueName1, true, false, false, null);
channel.queueDeclare(queueName2, true, false, false, null);
//创建队列，不指定队列，随机分配
//String queueName = channel.queueDeclare().getQueue();
channel.queueBind(queueName1, EXCHANGE_NAME, "");
System.out.println(" [xiaowang] Waiting for messages. To exit press CTRL+C");
//交换机绑定队列
channel.queueBind(queueName2, EXCHANGE_NAME, "");
System.out.println(" [xiaoli] Waiting for messages. To exit press CTRL+C");
DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println( " [xiaowang] Received '" + message + "'");
};
DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println( " [xiaoli] Received '" + message + "'");
};
channel.basicConsume(queueName1, true, deliverCallback1, consumerTag -> {
});
channel.basicConsume(queueName2, true, deliverCallback2, consumerTag -> {
});
}
}channel 频道：理解为操作消息队列的 Client，通过 channel 收发消息，提供了和消息对了 server 建立通信的传输方法
channel.queueDeclare 方法参数：
queue：这是一个字符串参数，代表要声明的队列的名称。如果队列不存在，则会自动创建一个新的队列。
durable：这是一个布尔值参数，表示队列是否持久化。如果设置为true，则队列会在服务器重启后仍然存在；如果设置为false，则队列在服务器重启后会被删除。默认值为false。
exclusive：这也是一个布尔值参数，表示队列是否为独占模式。如果设置为true，则只有当前连接可以访问该队列；如果设置为false，则其他连接也可以访问该队列。默认值为false。
autoDelete：这是另一个布尔值参数，表示队列是否自动删除。如果设置为true，则当最后一个消费者取消订阅时，队列将被删除；如果设置为false，则队列将一直存在，直到手动删除或服务器重启。默认值为false。
arguments：这是一个可选参数，用于设置队列的其他属性，比如消息的最大长度、最大优先级等。
channel.basicPublish 参数：
exchange：这是一个字符串参数，代表交换机的名称。如果不需要使用特定的交换机，可以传递一个空字符串（""）。交换机是RabbitMQ中用于接收生产者发送的消息并根据绑定规则路由到队列的组件。
routingKey：这也是一个字符串参数，它指定了发布消息的队列。无论通道绑定到哪个队列，最终发布的消息都会包含这个指定的路由键。路由键是用来确定消息应该发送到哪个队列的重要信息。
message：这是要发布的消息本身，通常是字节数组的形式。
properties：这是一个可选参数，用于设置消息的属性，比如消息的优先级、过期时间等。
在使用channel.basicPublish时，需要注意以下几点：
exchange和routingKey不能为空：在AMQImpl类中的实现要求这两个参数都不能为null，否则会抛出异常。
交换机类型：根据不同的需求，可以选择不同类型的交换机，如fanout、direct或topic。每种类型的交换机都有其特定的路由规则。
非命名队列：在某些情况下，比如日志系统，可以使用非命名队列，这样消费者可以接收到所有相关的日志消息，而不是特定的部分。
channel.basicConsume 参数：
queue：这是一个字符串参数，代表要消费的队列的名称。如果队列不存在，则会抛出异常。
onMessage：这是一个回调函数，当有新的消息到达时会被调用。该函数需要接收两个参数：一个表示消息内容的Delivery对象和一个表示通道的Channel对象。
consumerTag：这是一个可选参数，用于标识消费者。如果没有指定，则会自动生成一个唯一的标识符。
autoAck：这是一个布尔值参数，表示是否自动确认消息。如果设置为true，则在消息被处理后会自动发送确认信息；如果设置为false，则需要手动发送确认信息。默认值为false。
arguments：这是一个可选参数，用于设置消费者的其他属性，比如消息的最大长度、最大优先级等。
在使用channel.basicConsume时，需要注意以下几点：
队列名称：队列名称应该是唯一的，否则会抛出异常。
消息处理：在onMessage回调函数中，需要对消息进行处理，并根据需要发送确认信息。
消费者标识符：可以通过设置consumerTag来标识消费者，以便在后续操作中进行识别和管理。
消费者属性：可以通过设置消费者的其他属性来控制消费者的行为，比如设置消息的最大长度、最大优先级等。
路由交换机 （Direct exchange)
和订阅发布的区别是在交换机和队列之间有一个路由键，用来控制消息发送到哪个队列中供消费者消费。生产者给交换机一个标识，让交换机给指定的队列转发消息。
生产者代码
java
public class DirectProducer {
private static final String EXCHANGE_NAME = "direct_exchange";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
try (Connection connection = factory.newConnection();
Channel channel = connection.createChannel()) {
//创建交换机，交换机类型是 direct
channel.exchangeDeclare(EXCHANGE_NAME, "direct");
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()){
String userInput = scanner.nextLine();
//输入的时候带着标识，标识就是路由键
String[] strs = userInput.split(" ");
if(strs.length<1){
continue;
}
//消息
String message = strs[0];
//路由键
String severity = strs[1];
//发送消息时带着路由键
channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes("UTF-8"));
System.out.println(" [x] Sent '" + severity + "':'" + message + "'");
}
}
}
}消费者代码
java
public class DirectConsumer {
private static final String EXCHANGE_NAME = "direct_exchange";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.exchangeDeclare(EXCHANGE_NAME, "direct");
String queueName1 = "xiaohong";
String queueName2 = "xiaobai";
channel.queueDeclare(queueName1, true, false, false, null);
channel.queueDeclare(queueName2, true, false, false, null);
//交换机使用路由键绑定队列
channel.queueBind(queueName1, EXCHANGE_NAME, "xiaohong");
channel.queueBind(queueName2, EXCHANGE_NAME, "xiaobai");
System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [xiaohong] Received '" +
delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [xiaobai] Received '" +
delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
channel.basicConsume(queueName1, true, deliverCallback1, consumerTag -> {
});
channel.basicConsume(queueName2, true, deliverCallback2, consumerTag -> {
});
}
}主题交换机 （Topic exchange）
在路由交换机的基础上，消息会具有一个模糊的路由键转发给指定的对俄（一系列的路由键、一类的路由键）
-
（*）标识匹配一个单词，比如 *.orange 表示 a.orange b.orange 都能匹配
-
（#）表示 0 个或多个单词，比如 a,#, a.a, a.b 都可以
生产者代码
java
public class TopicProduce {
private static final String EXCHANGE_NAME = "topic_exchange1";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
try (Connection connection = factory.newConnection();
Channel channel = connection.createChannel()) {
channel.exchangeDeclare(EXCHANGE_NAME, "topic");
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()) {
String userInput = scanner.nextLine();
String[] strs = userInput.split(" ");
if (strs.length < 1) {
continue;
}
//消息
String message = strs[0];
//路由键
String severity = strs[1];
channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes("UTF-8"));
System.out.println(" [x] Sent '" + severity + "':'" + message + "'");
}
}
}
}消费者代码
java
public class TopicConsumer {
private static final String EXCHANGE_NAME = "topic_exchange1";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.exchangeDeclare(EXCHANGE_NAME, "topic");
channel.exchangeDeclare(EXCHANGE_NAME, "topic");
channel.exchangeDeclare(EXCHANGE_NAME, "topic");
String queueName1 = "xiaohei";
String queueName2 = "xiaolv";
String queueName3 = "xiaohuang";
channel.queueDeclare(queueName1, true, false, false, null);
channel.queueDeclare(queueName2, true, false, false, null);
channel.queueDeclare(queueName3, true, false, false, null);
//交换机使用路由键绑定队列，路由键绑定在第三个参数
channel.queueBind(queueName1, EXCHANGE_NAME, "#.前端.#");
channel.queueBind(queueName2, EXCHANGE_NAME, "#.后端.#");
channel.queueBind(queueName2, EXCHANGE_NAME, "#.产品.#");
System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
//收到消息后如何处理
DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [xiaohei] Received '" + delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [xiaolv] Received '" + delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
DeliverCallback deliverCallback3 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [xiaohuang] Received '" + delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
channel.basicConsume(queueName1, true, deliverCallback1, consumerTag -> {
});
channel.basicConsume(queueName2, true, deliverCallback2, consumerTag -> {
});
channel.basicConsume(queueName3, true, deliverCallback3, consumerTag -> {
});
}
}核心机制
消息过期机制
官方文档：Preventing Unbounded Buffers with RabbitMQ | RabbitMQ
每个消息指定一个有效期，一段时间内没有被消费者处理，就过期了。
比如消费者挂了，消息一直不被处理，订单就会失效。
可以清理过期的数据，模拟延迟队列的实现。
给每条消息都设置过期时间：
java
Map<String, Object> args = new HashMap<String, Object>();
args.put("x-message-ttl", 60000);
channel.queueDeclare(QUEUE_NAME, false, false, false, args);给队列设置过期时间，设置在生产者中
java
AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
.expiration("1000")
.build();生产者代码
java
public class TtlProducer {
private final static String QUEUE_NAME = "Tll_queue";
public static void main(String[] argv) throws Exception {
//创建连接
ConnectionFactory factory = new ConnectionFactory();
//设置了本地连接，如果修改了用户名和密码，需要设置
/*factory.setPassword();
factory.setUsername();*/
factory.setHost("localhost");
//建立连接、创建频道
//频道，类似客户端，用于调用server
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
String message = "Hello World!";
//发消息设置过期时间
AMQP.BasicProperties properties = new AMQP.BasicProperties.Builder()
.expiration("1000")
.build();
//发送消息
channel.basicPublish("",QUEUE_NAME,properties,message.getBytes(StandardCharsets.UTF_8));
System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
}
}消费者代码
java
public class TtlConsumer {
private final static String QUEUE_NAME = "Tll_queue";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
//声明队列，同一个消息队列参数必须一致
Map<String, Object> args = new HashMap<String, Object>();
args.put("x-message-ttl", 60000);
channel.queueDeclare(QUEUE_NAME, false, false, false, args);
//定义了如何处理消息
DeliverCallback deliverCallback = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [x] Received '" + message + "'");
};
//接收、消费消息 第二个参数 autoAck
channel.basicConsume(QUEUE_NAME, true, deliverCallback, consumerTag -> { });
System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
}
}死信队列
官方文档：Dead Letter Exchanges | RabbitMQ
为了保证消息的可靠性，比如每条消息都成功消费，需要提供一个容错机制，即：失效的消息怎么办？
死信：过期的消息、拒收的消息、消息队列满了、处理失败的消息的统称。
死信队列：处理死信的队列。
死信交换机：专门给死信队列转发消息的，存在路由绑定关系
实际就是设置一个普通的队列，专门将死信发送到这个队列中处理。
- 创建死信交换机和死信队列
java
//声明死信交换机
String queueName = "laoban_dlx_queue";
channel.queueDeclare(queueName, true, false, false, null);
channel.queueBind(queueName, EXCHANGE_NAME, "laoban");- 给失败之后需要容错处理的队列绑定死信交换机
java
args2.put("x-dead-letter-exchange", DEAD_EXCHANGE_NAME);- 绑定交换机到死信队列
java
args2.put("x-dead-letter-routing-key", "waibao");生产者代码
java
public class DLXDirectProducer {
private static final String EXCHANGE_NAME = "direct2_exchange";
private static final String DEAD_EXCHANGE_NAME = "dlx_direct2_exchange";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
try (Connection connection = factory.newConnection();
Channel channel = connection.createChannel()) {
//声明死信交换机
channel.exchangeDeclare(DEAD_EXCHANGE_NAME, "direct");
String queueName = "laoban_dlx_queue";
channel.queueDeclare(queueName, true, false, false, null);
channel.queueBind(queueName, DEAD_EXCHANGE_NAME, "laoban");
String queueName2 = "waibao_dlx_queue";
channel.queueDeclare(queueName2, true, false, false, null);
channel.queueBind(queueName2, DEAD_EXCHANGE_NAME, "waibao");
channel.exchangeDeclare(EXCHANGE_NAME, "direct");
DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [laoban] Received '" +
delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [waibao] Received '" +
delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
channel.basicConsume(queueName, false, deliverCallback1, consumerTag -> {
});
channel.basicConsume(queueName2, false, deliverCallback2, consumerTag -> {
});
Scanner scanner = new Scanner(System.in);
while (scanner.hasNext()){
String userInput = scanner.nextLine();
String[] strs = userInput.split(" ");
if(strs.length<1){
continue;
}
//消息
String message = strs[0];
//路由键
String severity = strs[1];
channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes("UTF-8"));
System.out.println(" [x] Sent '" + severity + "':'" + message + "'");
}
}
}
}消费者代码
java
public class DLXDirectConsumer {
private static final String EXCHANGE_NAME = "direct2_exchange";
private static final String DEAD_EXCHANGE_NAME = "dlx_direct2_exchange";
public static void main(String[] argv) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.exchangeDeclare(EXCHANGE_NAME, "direct");
//死信交换机绑定工作队列，当信息错误就从工作队列发送到死信交换机
Map<String, Object> args1 = new HashMap<String, Object>();
//指定绑定哪个交换机
args1.put("x-dead-letter-exchange", DEAD_EXCHANGE_NAME);
//死信要发送到哪个队列
args1.put("x-dead-letter-routing-key", "laoban");
String queueName1 = "doghuang";
channel.queueDeclare(queueName1, true, false, false, args1);
channel.queueBind(queueName1, EXCHANGE_NAME, "doghuang");
//绑定cat 队列
String queueName2 = "catbai";
Map<String, Object> args2 = new HashMap<String, Object>();
args2.put("x-dead-letter-exchange", DEAD_EXCHANGE_NAME);
args2.put("x-dead-letter-routing-key", "waibao");
channel.queueDeclare(queueName2, true, false, false, args2);
channel.queueBind(queueName2, EXCHANGE_NAME, "catbai");
//交换机使用路由键绑定队列
System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
DeliverCallback deliverCallback1 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
channel.basicNack(delivery.getEnvelope().getDeliveryTag(),false,false);
System.out.println(" [doghuang] Received '" +
delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
DeliverCallback deliverCallback2 = (consumerTag, delivery) -> {
String message = new String(delivery.getBody(), "UTF-8");
System.out.println(" [catbai] Received '" +
delivery.getEnvelope().getRoutingKey() + "':'" + message + "'");
};
channel.basicConsume(queueName1, false, deliverCallback1, consumerTag -> {
});
channel.basicConsume(queueName2, false, deliverCallback2, consumerTag -> {
});
}
}项目实战
项目中使用可以选择两种方法
-
官方的客户端，兼容性好，灵活，需要自己维护管理
-
使用封装好的客户端，比如 Spring Boot RabbitMQ Starter
优点：简单易用
缺点：不够灵活，被框架限制
小项目使用封装好的足够
- 依赖引入
引入和自己 Spring Boot 版本相同的依赖，避免出现不能运行的错误
XML
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-amqp -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-amqp</artifactId>
<version>2.6.13</version>
</dependency>- 引入配置
java
rabbitmq:
host: localhost
port: 5672
password: guest
username: guset- 创建交换机和消息队列，这个只需要启动一次创建即可
java
/**
* 只启动一次，创建交换机和消息队列
*/
public class MqInitMain {
private static final String EXCHANGE_NAME = "code_exchange";
public static void main(String[] args) throws Exception {
ConnectionFactory factory = new ConnectionFactory();
factory.setHost("localhost");
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.exchangeDeclare(EXCHANGE_NAME, "direct");
//绑定一个队列
String queueName = "code_queue";
channel.queueDeclare(queueName,true,false,false,null);
channel.queueBind(queueName,EXCHANGE_NAME,"BI_routingKey");
}
}- 生产者
java
/**
* 生产者
*/
@Component
public class MyMessageProducer {
@Resource
private RabbitTemplate rabbitTemplate;
//1.交换机名称2. 交换机路由键3.发送的消息
public void sendMessage(String exchange, String routingKey,String message){
rabbitTemplate.convertAndSend(exchange,routingKey,message);
}
}- 消费者
java
/**
* 消费者
*/
@Component
@Slf4j
public class MessageConsumer {
@RabbitListener(queues = {"code_queue"},ackMode = "MANUAL")
public void receiveMessage(String message, Channel channel,@Header(AmqpHeaders.DELIVERY_TAG) long delivery){
log.info("receiveMessage message={}",message);
try {
channel.basicAck(delivery,false);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}- 测试
java
@SpringBootTest
class MyMessageProducerTest {
@Resource
private MyMessageProducer myMessageProducer;
@Test
void sendMessage() {
myMessageProducer.sendMessage("code_exchange","BI_routingKey","你好吗");
}
}