我正在使用SpringBoot启动连接到RabbitMQ队列的SpringAMQP应用程序。我希望能够从生产者发送消息,指定回复队列,以便消费者只需要发送而无需调查目的地(因此不必在消息本身中传递回复数据)。 / p>
这是我的配置(在生产者和消费者之间共享)
private static final String QUEUE_NAME = "testQueue";
private static final String ROUTING_KEY = QUEUE_NAME;
public static final String REPLY_QUEUE = "replyQueue";
private static final String USERNAME = "guest";
private static final String PASSWORD = "guest";
private static final String IP = "localhost";
private static final String VHOST = "/";
private static final int PORT = 5672;
@Bean
public RabbitTemplate rabbitTemplate() {
RabbitTemplate template = new RabbitTemplate(connectionFactory());
amqpAdmin().declareQueue(new Queue(QUEUE_NAME));
amqpAdmin().declareQueue(new Queue(REPLY_QUEUE));
return template;
}
@Bean
public AmqpAdmin amqpAdmin() {
return new RabbitAdmin(connectionFactory());
}
@Bean
public ConnectionFactory connectionFactory() {
CachingConnectionFactory connectionFactory = new CachingConnectionFactory(IP);
connectionFactory.setUsername(USERNAME);
connectionFactory.setPassword(PASSWORD);
connectionFactory.setVirtualHost(VHOST);
connectionFactory.setPort(PORT);
return connectionFactory;
}
我发送的信息如下:
public Object sendAndReply(String queue, String content){
return template.convertSendAndReceive(queue, new Data(content), new MessagePostProcessor() {
@Override
public Message postProcessMessage(Message message) throws AmqpException {
message.getMessageProperties().setReplyTo(ReplyTester.REPLY_QUEUE);
return message;
}
});
}
等待回复如下:
public void replyToQueue(String queue){
template.receiveAndReply(queue, new ReceiveAndReplyCallback<Data, Data>() {
@Override
public Data handle(Data payload) {
System.out.println("Received: "+payload.toString());
return new Data("This is a reply for: "+payload.toString());
}
});
}
然而,当发送时,我得到以下异常:
Exception in thread "main" org.springframework.amqp.UncategorizedAmqpException: java.lang.IllegalArgumentException: Send-and-receive methods can only be used if the Message does not already have a replyTo property.
at org.springframework.amqp.rabbit.support.RabbitExceptionTranslator.convertRabbitAccessException(RabbitExceptionTranslator.java:66)
at org.springframework.amqp.rabbit.connection.RabbitAccessor.convertRabbitAccessException(RabbitAccessor.java:112)
at org.springframework.amqp.rabbit.core.RabbitTemplate.doExecute(RabbitTemplate.java:841)
at org.springframework.amqp.rabbit.core.RabbitTemplate.execute(RabbitTemplate.java:820)
at org.springframework.amqp.rabbit.core.RabbitTemplate.doSendAndReceiveWithTemporary(RabbitTemplate.java:705)
at org.springframework.amqp.rabbit.core.RabbitTemplate.doSendAndReceive(RabbitTemplate.java:697)
at org.springframework.amqp.rabbit.core.RabbitTemplate.convertSendAndReceive(RabbitTemplate.java:673)
at org.springframework.amqp.rabbit.core.RabbitTemplate.convertSendAndReceive(RabbitTemplate.java:663)
at prodsend.Prod.sendAndReply(ReplyTester.java:137)
at prodsend.ReplyTester.sendMessages(ReplyTester.java:49)
at prodsend.ReplyTester.main(ReplyTester.java:102)
Caused by: java.lang.IllegalArgumentException: Send-and-receive methods can only be used if the Message does not already have a replyTo property.
at org.springframework.util.Assert.isNull(Assert.java:89)
at org.springframework.amqp.rabbit.core.RabbitTemplate$6.doInRabbit(RabbitTemplate.java:711)
at org.springframework.amqp.rabbit.core.RabbitTemplate$6.doInRabbit(RabbitTemplate.java:705)
at org.springframework.amqp.rabbit.core.RabbitTemplate.doExecute(RabbitTemplate.java:835)
... 8 more
行ReplyTest.137指向上述return
方法中的sendAndReply
行。
编辑: 这是上面提到的Data类:)
class Data{
public String d;
public Data(String s){ d = s; }
public String toString() { return d; }
}
答案 0 :(得分:6)
基本RPC模式。使用特定路由密钥将消息发送到默认交换,并尝试接收响应。实现通常会将reply-to标头设置为独占队列,并等待一段时间限制超时。
因此方法convertSendAndReceive
处理设置replyTo
标头并返回Messaage
- 响应。这是同步模式 - RPC。
如果你想这样做异步 - 你似乎 - 不要使用这种方法。使用相应的convertAndSend
方法,并使用相应的MessagePostProcessor
添加replyTo
标头。
由于这是异步的,您需要注册单独的处理程序以接收回复。这需要在发送消息到另一方之前完成。然后在发送消息后的某个时刻调用此处理程序 - 何时未知。阅读Spring AQMP Documentation。
的 3.5.2 Asynchronous Consumer 部分所以,异步流程:
replyTo
queueue replyTo
设置receiveAndReply
,处理邮件,并向replyTo
同步流程是:
sendAndReceive
发送邮件并阻止receiveAndReply
,处理邮件,并向replyTo
所以后一种情况要求发件人等待。当您使用receiveXXX
而不是注册异步处理程序时,如果客户端需要一段时间来调用receiveXXX
,则发件人可能会等待很长时间。
顺便提一下,如果您想使用同步方法但使用特定replyTo
,则可以随时拨打setReplyQueue
。对于我提到的案例,还有一个setReplyTimeout
,客户要么没有阅读邮件或忘记回复。