必学消息队列-RabbitMQ(下集)
个人简介
作者是一个来自河源的大三在校生,以下笔记都是作者自学之路的一些浅薄经验,如有错误请指正,将来会不断的完善笔记,帮助更多的Java爱好者入门。
文章目录
什么是RabbitMQ
MQ全称为Message Queue, 消息队列(MQ)是一种应用程序对应用程序的通信方法。应用程序通过读写出入队列的消息(针对应用程序的数据)来通信,而无需专用连接来链接它们。消息传递指的是程序之间通过在消息中发送数据进行通信,而不是通过直接调用彼此来通信,直接调用通常是用于诸如远程过程调用的技术。排队指的是应用程序通过 队列来通信。队列的使用除去了接收和发送应用程序同时执行的要求。
MQ的特点
- MQ是消费-生产者模型的一个典型的代表,一端往消息队列中不断写入消息,而另一端则可以读取或者订阅队列中的消息。
- MQ遵循了AMQP协议的具体实现和产品。
MQ的使用场景
- 在项目中,将一些无需即时返回且耗时的操作提取出来,进行了异步处理,而这种异步处理的方式大大的节省了服务器的请求响应时间,从而提高了系统的吞吐量。
- 异步处理(常用)
- 应用解耦(常用)
- 流量削峰(常用)
各种MQ对比
在目前主流的消息队列中有(ActiveMQ,RocketMQ,RabbitMQ,kafka)
RabbitMQ在上面的各种消息队列中对于消息的保护是十分到位的(不会丢失消息),相对于kafka,虽然kafka性能十分强悍,在大数据中处理海量数据游刃有余,但是kafka容易丢失消息,而RabbitMQ虽然性能不及kafka,但是也不会很差,对于消息要求完整性很高的系统中用RabbitMQ十分好。
SpringBoot+RabbitMQ
导入启动器
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-amqp</artifactId> <version>2.3.9.RELEASE</version> </dependency>
application.yml
spring: rabbitmq: username: ems password: 123456 virtual-host: /ems host: localhost
自定义RabbitTemplate
SpringBoot默认使用CachingConnectionFactory连接工厂
@Configurationpublic class rabbitTemplateConfig { //注入SpringBoot默认的CachingConnectonFactory @Bean public RabbitTemplate rabbitTemplate(@Qualifier("rabbitConnectionFactory") CachingConnectionFactory cachingConnectionFactory){ RabbitTemplate rabbitTemplate = new RabbitTemplate(cachingConnectionFactory); /** * 当mandatory标志位设置为true时 * 如果exchange根据自身类型和消息routingKey无法找到一个合适的queue存储消息 * 那么broker会调用basic.return方法将消息返还给生产者 * 当mandatory设置为false时,出现上述情况broker会直接将消息丢弃 */ rabbitTemplate.setMandatory(true); //使用单独的发送连接,避免生产者由于各种原因阻塞而导致消费者同样阻塞 rabbitTemplate.setUsePublisherConnection(true); return rabbitTemplate; }}
RabbitTemplate实现发送消息
最简单的使用HelloWorld
经过SpringBoot整合的RabbitMQ,发送消息只要一条语句
对比如下:
原生RabbitMQ:(11行)
public static void main(String[] args) throws IOException, TimeoutException { ConnectionFactory factory = new ConnectionFactory(); factory.setUsername("ems"); factory.setPassword("123456"); factory.setVirtualHost("/ems"); //虚拟主机 factory.setHost("127.0.0.1"); //rabbitMQ的主机名(ip) Connection connection = factory.newConnection(); Channel channel = connection.createChannel(); channel.queueDeclare("hello",true,false,false,null); channel.basicPublish("","hello", MessageProperties.PERSISTENT_TEXT_PLAIN,"第一个RabbitMQ程序!!!".getBytes()); channel.close(); connection.close(); }
SpringBoot整合RabbitMQ:(1行)
@SpringBootTest@RunWith(SpringRunner.class)public class provider { @Autowired private RabbitTemplate rabbitTemplate; @Test public void send(){ //一条代码即可发送消息 /** * 参数1:交换机名称 * 参数2:路由键 * 参数3:消息内容(不需要转换成byte数组) */ rabbitTemplate.convertAndSend("","boot_hello","boot_helloWorld"); }}
@Component //所有RabbitMQ的消费者都需要“”加上“”Spring的组件注解,RabbitMQ消费者监听方法不用运行都可以被自动生效。。。。public class consumer { //RabbitMQ消费者监听方法 @RabbitListener(queuesToDeclare = {@Queue(name = "boot_hello",durable = "true",exclusive = "false" ,autoDelete = "false")}) public void receive(String msg){ System.out.println(msg); }}
workqueue模式
@SpringBootTest@RunWith(SpringRunner.class) //加载上下文public class workqueueTest { @Autowired private RabbitTemplate rabbitTemplate; @Test public void send(){// System.out.println(rabbitTemplate); for (int i = 0; i < 10; i++) { rabbitTemplate.convertAndSend("","boot_work","workqueue===>"+i); } } }
@Componentpublic class consumer1 { @RabbitListener(queuesToDeclare = @Queue(name = "boot_work",durable = "true")) public void receive1(String msg1){ System.out.println("consumer1===>"+msg1); }}@Componentclass consumer2{ @RabbitListener(queuesToDeclare = @Queue(name = "boot_work",durable = "true")) public void receive2(String msg2){ System.out.println("consumer2===>"+msg2); }}
fanout模式
@SpringBootTest@RunWith(SpringRunner.class)public class fanoutTest { @Autowired private RabbitTemplate rabbitTemplate; @Test public void test(){ rabbitTemplate.convertAndSend("boot_fanout","","hello"); } }
@Componentpublic class consumer3 { @RabbitListener(bindings = { @QueueBinding(value = @Queue,exchange = @Exchange(value = "boot_fanout",type = "fanout"),key = "") }) public void receive(String msg){ System.out.println("consumer1===>"+msg); }}@Componentclass consumer4{ @RabbitListener(bindings = @QueueBinding(value = @Queue,exchange = @Exchange(value = "boot_fanout",type = "fanout"),key = "")) public void receive(String msg){ System.out.println("consumer2===>"+msg); }}
direct模式
@SpringBootTest@RunWith(SpringRunner.class)public class directTest { @Autowired private RabbitTemplate rabbitTemplate; @Test public void test(){ rabbitTemplate.convertAndSend("direct_boot","user.log","direct"); }}
@Componentpublic class directConsumer1 { @RabbitListener(bindings = @QueueBinding(exchange = @Exchange(name = "direct_boot",type = "direct") ,value = @Queue,key = "user") ) public void receive(String msg){ System.out.println("consumer1===>"+msg); }}@Componentclass directConsumer2{ @RabbitListener(bindings = @QueueBinding(exchange = @Exchange(name = "direct_boot",type = "direct") ,value = @Queue,key = "user.log" )) public void receive(String msg){ System.out.println("consumer2==>"+msg); }}
topic模式
@SpringBootTest@RunWith(SpringRunner.class)public class topicTest { @Autowired private RabbitTemplate rabbitTemplate; @Test public void test(){ rabbitTemplate.convertAndSend("topic_boot","user.hello.log","hello"); }}
@Componentpublic class topicConsumer1 { @RabbitListener(bindings = @QueueBinding(exchange = @Exchange(value = "topic_boot",type = "topic") ,value = @Queue,key = "user.#" )) public void receive(String msg){ System.out.println("consumer1==>"+msg); }}@Componentclass topicConsumer2{ @RabbitListener(bindings = @QueueBinding(exchange = @Exchange(value = "topic_boot",type = "topic") ,value = @Queue,key = "user.*" )) public void receive(String msg){ System.out.println("consumer2==>"+msg); }}
RabbitMQ高级特性
消息队列的过期时间ttl
如果我们设置了消息队列的过期时间,假设我们设置了5000ms,5000ms过去了,如果这个队列还有未被消费的消息,那么这些消息将会被自动丢弃(无法找回)。。。。
队列里的消息的过期时间(有点坑)
消费者的消息的过期时间
设置消息队列的argument为x-message-ttl 为xxx值,比如value=“5000”,就是5秒过去了,消息队列未被消费的消息将会直接丢弃
坑:@argument注解设置参数一定要指定类型为Number子类,比如java.lang.Integer,不然会报错
比如:arguments = {@Argument(name = “x-message-ttl”,value = “5000”,type = “java.lang.Integer”)}
spring: rabbitmq: username: ems password: 123456 virtual-host: /ems host: localhost listener: direct: acknowledge-mode: manual #手动确认 simple: acknowledge-mode: manual #手动确认
@Test public void test1(){ MessageProperties messageProperties = new MessageProperties(); String msg = "hello_ttl"; Message message = new Message(msg.getBytes(),messageProperties); rabbitTemplate.convertAndSend("ttl_queue","ttl_a",message); }
/** * ==小坑: * 使用RabbitListener实现队列的过期时间ttl必须要指定argument的“type”为Number类的子类,比如java.lang.Integer * =======切记,ttl和消息队列长度都要用Number的子类,使用默认的会报错====== * 因为argument默认是java.lang.String类型,必须修改。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。 * 。。。 */ //@Queue和@Exchange指定value就会使这个队列和交换机设置为不过期的,没有value就是暂时的 @RabbitListener(bindings = @QueueBinding(value = @Queue(value = "ttl_temp",durable = "true" ,arguments = {@Argument(name = "x-message-ttl",value = "5000",type = "java.lang.Integer")}//一定要指定类型 ) ,exchange = @Exchange(value = "ttl_queue",type = "direct"),key = {"ttl_a"} )) public void receive(String msg,Message message,Channel channel){ System.out.println("msg==="+msg); System.out.println("message==="+message); System.out.println("channel==="+channel);// try {// channel.basicAck(message.getMessageProperties().getDeliveryTag(),false); //手动确认// } catch (IOException e) {// e.printStackTrace();// } }
指定消息的过期时间
生产者消息的过期时间
核心代码:messageProperties.setExpiration(“5000”);
@Test public void test2(){ MessageProperties messageProperties = new MessageProperties(); messageProperties.setExpiration("5000"); //设置指定消息的过期时间 String str="ttl_test2"; Message message = new Message(str.getBytes(),messageProperties); rabbitTemplate.convertAndSend("","ttl_declare",message); }
@RabbitListener(queuesToDeclare = @Queue(name = "ttl_declare")) public void receive1(String msg,Message message,Channel channel) throws IOException { System.out.println(msg);// channel.basicAck(message.getMessageProperties().getDeliveryTag(),false); }
死信队列
消息放进死信队列的条件:
1:消息过期了,如果有死信队列则放入死信队列,如果没有死信队列则直接丢弃无法找回。
2:某个消息队列长度已经达到最大值,此时在把消息发送到这个队列中,如果有死信队列则放入死信队列,没有则丢弃
3:消息被拒绝(basic.reject / basic.nack)
================创建死信队列步骤
1:创建一个普通队列
@SpringBootTest@RunWith(SpringRunner.class)public class deadLetter { @Autowired private RabbitTemplate rabbitTemplate; @Test public void test(){ Message message = new Message("deadLetter".getBytes(),new MessageProperties()); rabbitTemplate.convertAndSend("","nomal_dead",message); }}
@Componentpublic class nomalQueue { /** * 这里我们只演示一种消息放入死信队列的情况(当消息过期后) * 在某个队列设置了x-dead-letter-exchange和x-dead-letter-routing-key后,如果出现丢弃消息就会 * 通过x-dead-letter-exchange和x-dead-letter-routing-key找到指定的队列,这个队列就会默认是死信队列 * 其实死信队列也是正常的队列。。。。配置全都一样 */ @RabbitListener(queuesToDeclare = @Queue(value = "nomal_dead",arguments = { @Argument(name = "x-message-ttl",value = "5000",type = "java.lang.Integer"), @Argument(name = "x-dead-letter-exchange",value = "deadletter_exchange1"), @Argument(name = "x-dead-letter-routing-key",value = "deadletter_key1") } )) public void receive(String msg, Message message, Channel channel){ System.out.println("msg1="+msg); }}
@Componentpublic class deadLetterQueue { /** * 这里的交换机和路由key都要和配置的死信交换机、死信路由key一样。 */ @RabbitListener(bindings = @QueueBinding(value = @Queue("deadLetterQueue") ,exchange = @Exchange(value = "deadletter_exchange1",type = "direct") ,key = "deadletter_key1" )) public void receive_deadLetter(String msg){ System.out.println(msg); }}
固定长度的消息队列
核心代码:arguments = @Argument(name = “x-max-length”,value = “6”,type = “java.lang.Integer”)
@Test public void test(){ Message message = new Message(("max").getBytes(),new MessageProperties()); rabbitTemplate.convertAndSend("","maxLength_queue",message); }
@RabbitListener(queuesToDeclare = @Queue(value = "maxLength_queue",durable = "true" ,arguments = @Argument(name = "x-max-length",value = "6",type = "java.lang.Integer") )) public void receive(String msg, Message message, Channel channel) throws IOException { System.out.println(msg); }
延时队列
应用场景:下了订单过了30分钟未支付,然后就自动取消订单
rabbitmq本身是没有延迟队列的,我们可以通过ttl过期时间和死信队列(DLX)来实现