RabbitMQ - mandatory参数
作者:互联网
参考:<<RabbitMQ实战指南>>
mandatory和immediate是channel.basicPublish方法中的两个参数,它们都有当消息传递过程中不可达目的地时将消息返回给生产者的功能。
RabbitMQ 3.0版本开始去掉了对immediate参数的支持,这里就不在讨论该参数。
1. 发送消息api:
void basicPublish(String exchange, String routingKey, BasicProperties props, byte[] body) throws IOException;
void basicPublish(String exchange, String routingKey, boolean mandatory, BasicProperties props, byte[] body) throws IOException;
void basicPublish(String exchange, String routingKey, boolean mandatory, boolean immediate, BasicProperties props, byte[] body) throws IOException;
参数说明:
- exchange:交换器名称,指定消息需要发送到哪个交换器中。如果设置为空字符串,则消息会被发送到RabbitMQ默认的交换器中。
- routingKey:路由键,交换器根据路由键将消息存储到相应的队列之中。
- mandatory:交换器无法根据自身类型和路由键找到一个符合条件的队列时的处理方式
- true:RabbitMQ会调用Basic.Return命令将消息返回给生产者
- false:RabbitMQ会把消息直接丢弃
- immediate:设置true时,如果该消息关联的队列上有消费者,则立即投递,否则这条消息不存入队列;如果与路由键匹配的所有队列都没有消费者时,该消息会通过Basic.Return返回至生产者
- props:消息属性集,包含14个属性成员,如持久化、优先级、投递模式、过期时间等等
- body:消息体,需要发送的消息
2.获取没有被正确路由的消息
mandatory设置为true之后,生产者通过调用channel.addReturnListener()方法来添加ReturnListener监听器,实现获取没有被正确路由到合适队列的消息。有以下几种情形:
- 交换器没有绑定任何队列
- 路由键错误,即交换器无法根据路由键投递消息到队列
注:如果是无法路由到交换器上,则不会触发Basic.Return命令,也就是监听器不会接收到无法路由的消息。
3.示例
3.1 原生api
// 获取Connection、创建Channel步骤略
// 声明交换器
String exchangeName = "direct.exchange.test.mandatory";
AMQP.Exchange.DeclareOk declareOk = channel.exchangeDeclare(exchangeName, "direct", true);
// 声明队列
String queueName = "direct.queue.test.mandatory";
Map<String, Object> arguments = new HashMap<>();
String queue = channel.queueDeclare(queueName, true, false, false, null).getQueue();
// 绑定交换器和队列
String routingKey = "direct.routing-key.test.mandatory";
channel.queueBind(queue, exchangeName, routingKey);
// 正常路由的消息
channel.basicPublish(exchangeName, routingKey, true, MessageProperties.TEXT_PLAIN, "Test Msg".getBytes("UTF-8"));
// 不可路由的消息
channel.basicPublish(exchangeName, routingKey + "2", true, MessageProperties.TEXT_PLAIN, "Test Msg2".getBytes("UTF-8"));
channel.addReturnListener(new ReturnListener() {
@Override
public void handleReturn(int replyCode, String replyText, String exchange, String routingKey, AMQP.BasicProperties properties, byte[] body) throws IOException {
String message = new String(body, "UTF-8");
System.out.println(message);
}
});
3.2 springboot
(1)添加rabbitmq的starter
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-amqp</artifactId>
</dependency>
(2)application.yml
通过spring.rabbitmq.publisher-returns=true
属性以及实现org.springframework.amqp.rabbit.core.RabbitTemplate.RabbitTemplate.ReturnCallback
接口来接收无法路由的消息。
实际上,最终还是利用channel.basicPublish()方法,将mandatory设置为true来实现。
spring:
rabbitmq:
host: dev.tss.com
port: 5672
username: admin
password: njittss
# 开启发送确认
# publisher-confirms: true
# 开启发送失败退回,或者通过rabbitTemplate.setMandatory(true);设置
publisher-returns: true
rabbitmq:
direct:
test:
mandatory:
exchangeName: direct.exchange.test.mandatory
queueName: direct.queue.test.mandatory
routingKey: direct.routing-key.test.mandatory
(3)添加监听器
@Component
public class RabbitCallback implements RabbitTemplate.ReturnCallback {
private static final Logger LOGGER = LoggerFactory.getLogger(RabbitCallback.class);
@Autowired
private RabbitTemplate rabbitTemplate;
@PostConstruct
public void init() {
// 也可以通过这种方式配置
// rabbitTemplate.setMandatory(true);
// 每个RabbitTemplate只能设置一个RabbitTemplate.ReturnCallback
rabbitTemplate.setReturnCallback(this);
}
/**
* 交换机路由到队列失败才会回调
*/
@Override
public void returnedMessage(Message message, int replyCode, String replyText, String exchange, String routingKey) {
LOGGER.warn("return callback, receive message :" + message.toString() + ", " + replyText + ", " + exchange + ", " + routingKey);
}
}
(4)发送消息测试
当调用sendAbnormalMessage()方法发送消息时,监听器会收到无法路由到队列的消息。
@Value("${rabbitmq.direct.test.mandatory.exchangeName}")
private String exchangeName;
@Value("${rabbitmq.direct.test.mandatory.routingKey}")
private String routingKey;
@Autowired
private RabbitTemplate rabbitTemplate;
// 测试发送可以路由的消息
public boolean sendNormalMessage() {
String message = "test normal message";
this.rabbitTemplate.convertAndSend(exchangeName, routingKey, message);
return true;
}
// 测试发送不可路由的消息
public boolean sendAbnormalMessage() {
String message = "test abnormal message";
this.rabbitTemplate.convertAndSend(exchangeName, routingKey + "2", message);
return true;
}
最后扒一下spring发送消息设置mandatory逻辑:
- 通过
rabbitTemplate.convertAndSend(exchangeName, routingKey, message)
方法发送消息,这是个重载方法。 - 继续debug,还是在RabbitTemplate类中,先调用了send()方法,再由匿名内部类调用doSend()方法,结合doSend参数来看,就是由
RabbitTemplate.this.returnCallback != null && RabbitTemplate.this.mandatoryExpression.getValue(RabbitTemplate.this.evaluationContext, message, Boolean.class)
这段逻辑确定了mandatory参数是true还是false。翻译过来就是:设置了ReturnCallback以及属性spring.rabbitmq.publisher-returns=true(或rabbitTemplate.setMandatory(true))
public void send(final String exchange, final String routingKey, final Message message, final CorrelationData correlationData) throws AmqpException {
execute(new ChannelCallback<Object>() {
@Override
public Object doInRabbit(Channel channel) throws Exception {
doSend(channel, exchange, routingKey, message,
RabbitTemplate.this.returnCallback != null && RabbitTemplate.this.mandatoryExpression.getValue(RabbitTemplate.this.evaluationContext, message, Boolean.class),
correlationData);
return null;
}
}, obtainTargetConnectionFactory(this.sendConnectionFactorySelectorExpression, message));
}
protected void doSend(Channel channel, String exchange, String routingKey, Message message,
boolean mandatory, CorrelationData correlationData) throws Exception {
// ...
Message messageToUse = message;
MessageProperties messageProperties = messageToUse.getMessageProperties();
if (mandatory) {
messageProperties.getHeaders().put(PublisherCallbackChannel.RETURN_CORRELATION_KEY, this.uuid);
}
// ...
// 发送消息
channel.basicPublish(exchange, routingKey, mandatory, convertedMessageProperties, messageToUse.getBody());
// ...
}
标签:mandatory,String,RabbitMQ,参数,message,true,路由,routingKey 来源: https://blog.csdn.net/mytt_10566/article/details/90741398