rabbitmq channel参数详解
1、Channel
1.1 channel.exchangeDeclare()：
type：有direct、fanout、topic三种
durable：true、false true：服务器重启会保留下来Exchange。警告：仅设置此选项，不代表消息持久化。即不保证重启后消息还在。原文：true if we are declaring a durable exchange (the exchange will survive a server restart)
autoDelete:true、false.true:当已经没有消费者时，服务器是否可以删除该Exchange。原文1：true if the server should delete the exchange when it is no longer in use。
/** * Declare an exchange. * @see com.rabbitmq.client.AMQP.Exchange.Declare * @see com.rabbitmq.client.AMQP.Exchange.DeclareOk * @param exchange the name of the exchange * @param type the exchange type * @param durable true if we are declaring a durable exchange (the exchange will survive a server restart) * @param autoDelete true if the server should delete the exchange when it is no longer in use * @param arguments other properties (construction arguments) for the exchange * @return a declaration-confirm method to indicate the exchange was successfully declared * @throws java.io.IOException if an error is encountered */ Exchange.DeclareOk exchangeDeclare(String exchange, String type, boolean durable, boolean autoDelete, Map<String, Object> arguments) throws IOException;
1.2 chanel.basicQos()
prefetchSize：0
prefetchCount：会告诉RabbitMQ不要同时给一个消费者推送多于N个消息，即一旦有N个消息还没有ack，则该consumer将block掉，直到有消息ack
global：true\false 是否将上面设置应用于channel，简单点说，就是上面限制是channel级别的还是consumer级别
备注：据说prefetchSize 和global这两项，rabbitmq没有实现，暂且不研究
/** * Request specific "quality of service" settings. * * These settings impose limits on the amount of data the server * will deliver to consumers before requiring acknowledgements. * Thus they provide a means of consumer-initiated flow control. * @see com.rabbitmq.client.AMQP.Basic.Qos * @param prefetchSize maximum amount of content (measured in * octets) that the server will deliver, 0 if unlimited * @param prefetchCount maximum number of messages that the server * will deliver, 0 if unlimited * @param global true if the settings should be applied to the * entire channel rather than each consumer * @throws java.io.IOException if an error is encountered */ void basicQos(int prefetchSize, int prefetchCount, boolean global) throws IOException;
1.3 channel.basicPublish()
routingKey：路由键，#匹配0个或多个单词，*匹配一个单词，在topic exchange做消息转发用
mandatory：true：如果exchange根据自身类型和消息routeKey无法找到一个符合条件的queue，那么会调用basic.return方法将消息返还给生产者。false：出现上述情形broker会直接将消息扔掉
immediate：true：如果exchange在将消息route到queue(s)时发现对应的queue上没有消费者，那么这条消息不会放入队列中。当与消息routeKey关联的所有queue(一个或多个)都没有消费者时，该消息会通过basic.return方法返还给生产者。
BasicProperties ：需要注意的是BasicProperties.deliveryMode，0:不持久化 1：持久化 这里指的是消息的持久化，配合channel(durable=true),queue(durable)可以实现，即使服务器宕机，消息仍然保留
简单来说：mandatory标志告诉服务器至少将该消息route到一个队列中，否则将消息返还给生产者；immediate标志告诉服务器如果该消息关联的queue上有消费者，则马上将消息投递给它，如果所有queue都没有消费者，直接把消息返还给生产者，不用将消息入队列等待消费者了。
/** * Publish a message. * * Publishing to a non-existent exchange will result in a channel-level * protocol exception, which closes the channel. * * Invocations of <code>Channel#basicPublish</code> will eventually block if a * <a href="http://www.rabbitmq.com/alarms.html">resource-driven alarm</a> is in effect. * * @see com.rabbitmq.client.AMQP.Basic.Publish * @see <a href="http://www.rabbitmq.com/alarms.html">Resource-driven alarms</a>. * @param exchange the exchange to publish the message to * @param routingKey the routing key * @param mandatory true if the 'mandatory' flag is to be set * @param immediate true if the 'immediate' flag is to be * set. Note that the RabbitMQ server does not support this flag. * @param props other properties for the message - routing headers etc * @param body the message body * @throws java.io.IOException if an error is encountered */ void basicPublish(String exchange, String routingKey, boolean mandatory, boolean immediate, BasicProperties props, byte[] body) throws IOException;
1.4 channel.basicAck();
deliveryTag:该消息的index
multiple：是否批量.true:将一次性ack所有小于deliveryTag的消息。
/** * Acknowledge one or several received * messages. Supply the deliveryTag from the {@link com.rabbitmq.client.AMQP.Basic.GetOk} * or {@link com.rabbitmq.client.AMQP.Basic.Deliver} method * containing the received message being acknowledged. * @see com.rabbitmq.client.AMQP.Basic.Ack * @param deliveryTag the tag from the received {@link com.rabbitmq.client.AMQP.Basic.GetOk} or {@link com.rabbitmq.client.AMQP.Basic.Deliver} * @param multiple true to acknowledge all messages up to and * including the supplied delivery tag; false to acknowledge just * the supplied delivery tag. * @throws java.io.IOException if an error is encountered */ void basicAck(long deliveryTag, boolean multiple) throws IOException;
1.5 channel.basicNack(delivery.getEnvelope().getDeliveryTag(), false, true);
deliveryTag:该消息的index
multiple：是否批量.true:将一次性拒绝所有小于deliveryTag的消息。
requeue：被拒绝的是否重新入队列
/** * Reject one or several received messages. * * Supply the <code>deliveryTag</code> from the {@link com.rabbitmq.client.AMQP.Basic.GetOk} * or {@link com.rabbitmq.client.AMQP.Basic.GetOk} method containing the message to be rejected. * @see com.rabbitmq.client.AMQP.Basic.Nack * @param deliveryTag the tag from the received {@link com.rabbitmq.client.AMQP.Basic.GetOk} or {@link com.rabbitmq.client.AMQP.Basic.Deliver} * @param multiple true to reject all messages up to and including * the supplied delivery tag; false to reject just the supplied * delivery tag. * @param requeue true if the rejected message(s) should be requeued rather * than discarded/dead-lettered * @throws java.io.IOException if an error is encountered */ void basicNack(long deliveryTag, boolean multiple, boolean requeue) throws IOException;
1.5 channel.basicReject(delivery.getEnvelope().getDeliveryTag(), false);
deliveryTag:该消息的index
requeue：被拒绝的是否重新入队列
channel.basicNack 与 channel.basicReject 的区别在于basicNack可以拒绝多条消息，而basicReject一次只能拒绝一条消息
/** * Reject a message. Supply the deliveryTag from the {@link com.rabbitmq.client.AMQP.Basic.GetOk} * or {@link com.rabbitmq.client.AMQP.Basic.Deliver} method * containing the received message being rejected. * @see com.rabbitmq.client.AMQP.Basic.Reject * @param deliveryTag the tag from the received {@link com.rabbitmq.client.AMQP.Basic.GetOk} or {@link com.rabbitmq.client.AMQP.Basic.Deliver} * @param requeue true if the rejected message should be requeued rather than discarded/dead-lettered * @throws java.io.IOException if an error is encountered */ void basicReject(long deliveryTag, boolean requeue) throws IOException;
1.6 channel.basicConsume(QUEUE_NAME, true, consumer);
autoAck：是否自动ack，如果不自动ack，需要使用channel.ack、channel.nack、channel.basicReject 进行消息应答
/** * Start a non-nolocal, non-exclusive consumer, with * a server-generated consumerTag. * @param queue the name of the queue * @param autoAck true if the server should consider messages * acknowledged once delivered; false if the server should expect * explicit acknowledgements * @param callback an interface to the consumer object * @return the consumerTag generated by the server * @throws java.io.IOException if an error is encountered * @see com.rabbitmq.client.AMQP.Basic.Consume * @see com.rabbitmq.client.AMQP.Basic.ConsumeOk * @see #basicConsume(String, boolean, String, boolean, boolean, Map, Consumer) */ String basicConsume(String queue, boolean autoAck, Consumer callback) throws IOException;
1.7 chanel.exchangeBind()
channel.queueBind(queueName, EXCHANGE_NAME, bindingKey);
用于通过绑定bindingKey将queue到Exchange，之后便可以进行消息接收
/** * Bind an exchange to an exchange, with no extra arguments. * @see com.rabbitmq.client.AMQP.Exchange.Bind * @see com.rabbitmq.client.AMQP.Exchange.BindOk * @param destination the name of the exchange to which messages flow across the binding * @param source the name of the exchange from which messages flow across the binding * @param routingKey the routine key to use for the binding * @return a binding-confirm method if the binding was successfully created * @throws java.io.IOException if an error is encountered */ Exchange.BindOk exchangeBind(String destination, String source, String routingKey) throws IOException;
1.8 channel.queueDeclare(QUEUE_NAME, false, false, false, null);
durable：true、false true：在服务器重启时，能够存活
exclusive ：是否为当前连接的专用队列，在连接断开后，会自动删除该队列，生产环境中应该很少用到吧。
autodelete：当没有任何消费者使用时，自动删除该队列。this means that the queue will be deleted when there are no more processes consuming messages from it.
/** * Declare a queue * @see com.rabbitmq.client.AMQP.Queue.Declare * @see com.rabbitmq.client.AMQP.Queue.DeclareOk * @param queue the name of the queue * @param durable true if we are declaring a durable queue (the queue will survive a server restart) * @param exclusive true if we are declaring an exclusive queue (restricted to this connection) * @param autoDelete true if we are declaring an autodelete queue (server will delete it when no longer in use) * @param arguments other properties (construction arguments) for the queue * @return a declaration-confirm method to indicate the queue was successfully declared * @throws java.io.IOException if an error is encountered */ Queue.DeclareOk queueDeclare(String queue, boolean durable, boolean exclusive, boolean autoDelete, Map<String, Object> arguments) throws IOException;
参考：http://blog.csdn.net/jiao_fuyou/article/details/21594947
