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  • 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。

     1  /**
     2      * Declare an exchange.
     3      * @see com.rabbitmq.client.AMQP.Exchange.Declare
     4      * @see com.rabbitmq.client.AMQP.Exchange.DeclareOk
     5      * @param exchange the name of the exchange
     6      * @param type the exchange type
     7      * @param durable true if we are declaring a durable exchange (the exchange will survive a server restart)
     8      * @param autoDelete true if the server should delete the exchange when it is no longer in use
     9      * @param arguments other properties (construction arguments) for the exchange
    10      * @return a declaration-confirm method to indicate the exchange was successfully declared
    11      * @throws java.io.IOException if an error is encountered
    12      */
    13     Exchange.DeclareOk exchangeDeclare(String exchange, String type, boolean durable, boolean autoDelete,
    14                                        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:truefalse 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

     1    /**
     2      * Request specific "quality of service" settings.
     3      *
     4      * These settings impose limits on the amount of data the server
     5      * will deliver to consumers before requiring acknowledgements.
     6      * Thus they provide a means of consumer-initiated flow control.
     7      * @see com.rabbitmq.client.AMQP.Basic.Qos
     8      * @param prefetchSize maximum amount of content (measured in
     9      * octets) that the server will deliver, 0 if unlimited
    10      * @param prefetchCount maximum number of messages that the server
    11      * will deliver, 0 if unlimited
    12      * @param global true if the settings should be applied to the
    13      * entire channel rather than each consumer
    14      * @throws java.io.IOException if an error is encountered
    15      */
    16     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。

     1   /**
     2      * Publish a message.
     3      *
     4      * Publishing to a non-existent exchange will result in a channel-level
     5      * protocol exception, which closes the channel.
     6      *
     7      * Invocations of <code>Channel#basicPublish</code> will eventually block if a
     8      * <a href="http://www.rabbitmq.com/alarms.html">resource-driven alarm</a> is in effect.
     9      *
    10      * @see com.rabbitmq.client.AMQP.Basic.Publish
    11      * @see <a href="http://www.rabbitmq.com/alarms.html">Resource-driven alarms</a>.
    12      * @param exchange the exchange to publish the message to
    13      * @param routingKey the routing key
    14      * @param mandatory true if the 'mandatory' flag is to be set
    15      * @param immediate true if the 'immediate' flag is to be
    16      * set. Note that the RabbitMQ server does not support this flag.
    17      * @param props other properties for the message - routing headers etc
    18      * @param body the message body
    19      * @throws java.io.IOException if an error is encountered
    20      */
    21     void basicPublish(String exchange, String routingKey, boolean mandatory, boolean immediate, BasicProperties props, byte[] body)
    22             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。

     1     /**
     2      * Acknowledge one or several received
     3      * messages. Supply the deliveryTag from the {@link com.rabbitmq.client.AMQP.Basic.GetOk}
     4      * or {@link com.rabbitmq.client.AMQP.Basic.Deliver} method
     5      * containing the received message being acknowledged.
     6      * @see com.rabbitmq.client.AMQP.Basic.Ack
     7      * @param deliveryTag the tag from the received {@link com.rabbitmq.client.AMQP.Basic.GetOk} or {@link com.rabbitmq.client.AMQP.Basic.Deliver}
     8      * @param multiple true to acknowledge all messages up to and
     9      * including the supplied delivery tag; false to acknowledge just
    10      * the supplied delivery tag.
    11      * @throws java.io.IOException if an error is encountered
    12      */
    13     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

     1     /**
     2      * Reject one or several received messages.
     3      *
     4      * Supply the <code>deliveryTag</code> from the {@link com.rabbitmq.client.AMQP.Basic.GetOk}
     5      * or {@link com.rabbitmq.client.AMQP.Basic.GetOk} method containing the message to be rejected.
     6      * @see com.rabbitmq.client.AMQP.Basic.Nack
     7      * @param deliveryTag the tag from the received {@link com.rabbitmq.client.AMQP.Basic.GetOk} or {@link com.rabbitmq.client.AMQP.Basic.Deliver}
     8      * @param multiple true to reject all messages up to and including
     9      * the supplied delivery tag; false to reject just the supplied
    10      * delivery tag.
    11      * @param requeue true if the rejected message(s) should be requeued rather
    12      * than discarded/dead-lettered
    13      * @throws java.io.IOException if an error is encountered
    14      */
    15     void basicNack(long deliveryTag, boolean multiple, boolean requeue)
    16             throws IOException;

    1.6 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

     1  /**
     2      * Reject a message. Supply the deliveryTag from the {@link com.rabbitmq.client.AMQP.Basic.GetOk}
     3      * or {@link com.rabbitmq.client.AMQP.Basic.Deliver} method
     4      * containing the received message being rejected.
     5      * @see com.rabbitmq.client.AMQP.Basic.Reject
     6      * @param deliveryTag the tag from the received {@link com.rabbitmq.client.AMQP.Basic.GetOk} or {@link com.rabbitmq.client.AMQP.Basic.Deliver}
     7      * @param requeue true if the rejected message should be requeued rather than discarded/dead-lettered
     8      * @throws java.io.IOException if an error is encountered
     9      */
    10     void basicReject(long deliveryTag, boolean requeue) throws IOException;

    1.7 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

     1     /**
     2      * Start a non-nolocal, non-exclusive consumer, with
     3      * a server-generated consumerTag.
     4      * @param queue the name of the queue
     5      * @param autoAck true if the server should consider messages
     6      * acknowledged once delivered; false if the server should expect
     7      * explicit acknowledgements
     8      * @param callback an interface to the consumer object
     9      * @return the consumerTag generated by the server
    10      * @throws java.io.IOException if an error is encountered
    11      * @see com.rabbitmq.client.AMQP.Basic.Consume
    12      * @see com.rabbitmq.client.AMQP.Basic.ConsumeOk
    13      * @see #basicConsume(String, boolean, String, boolean, boolean, Map, Consumer)
    14      */
    15     String basicConsume(String queue, boolean autoAck, Consumer callback) throws IOException;

    1.8 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

     1     /**
     2      * Bind an exchange to an exchange, with no extra arguments.
     3      * @see com.rabbitmq.client.AMQP.Exchange.Bind
     4      * @see com.rabbitmq.client.AMQP.Exchange.BindOk
     5      * @param destination the name of the exchange to which messages flow across the binding
     6      * @param source the name of the exchange from which messages flow across the binding
     7      * @param routingKey the routine key to use for the binding
     8      * @return a binding-confirm method if the binding was successfully created
     9      * @throws java.io.IOException if an error is encountered
    10      */
    11     Exchange.BindOk exchangeBind(String destination, String source, String routingKey) throws IOException;

    1.9 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.

     1  /**
     2      * Declare a queue
     3      * @see com.rabbitmq.client.AMQP.Queue.Declare
     4      * @see com.rabbitmq.client.AMQP.Queue.DeclareOk
     5      * @param queue the name of the queue
     6      * @param durable true if we are declaring a durable queue (the queue will survive a server restart)
     7      * @param exclusive true if we are declaring an exclusive queue (restricted to this connection)
     8      * @param autoDelete true if we are declaring an autodelete queue (server will delete it when no longer in use)
     9      * @param arguments other properties (construction arguments) for the queue
    10      * @return a declaration-confirm method to indicate the queue was successfully declared
    11      * @throws java.io.IOException if an error is encountered
    12      */
    13     Queue.DeclareOk queueDeclare(String queue, boolean durable, boolean exclusive, boolean autoDelete,
    14                                  Map<String, Object> arguments) throws IOException;

    参考:http://blog.csdn.net/jiao_fuyou/article/details/21594947
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  • 原文地址:https://www.cnblogs.com/pengpengzhang/p/9405138.html
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