RabbitMq學習（一）

一 RabbitMq的重要概念

1. Exchanges ：交換器，必須的作用類似於轉換器，可以將消息通過routeKey轉發到對應的隊列中；
2. routeKey：路由鍵，類似於路牌，生產着將要發送的消息發到交換器上，並指定路由鍵，然後交換器通過路由鍵將消息發送到對應的queue中；
3. Queue：消息隊列。消息的載體。
4. Binding：作用就是將Exchange和Queue按照某種路由規則綁定起來。

二 如何使用rabbitmq提供的客戶端

		<dependency>
            <groupId>com.rabbitmq</groupId>
            <artifactId>amqp-client</artifactId>
            <version>5.2.0</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.25</version>
        </dependency>

1. 創建一個ConnectionFactory,並設置一系列的屬性

	ConnectionFactory connectionFactory = new ConnectionFactory();
 	connectionFactory.setHost("192.168.0.107");//設置主機名稱
 	connectionFactory.setPort(5672);//端口
    connectionFactory.setUsername("mqadmin");//用戶名
    connectionFactory.setPassword("mqadminpassword");//密碼
    connectionFactory.setConnectionTimeout(3000);//超時時間

2. 通過connectionFactory創建一個連接，通過該鏈接創建一個Channel，所有的操作都是基於Channel進行的(工廠模式無處不在)

	Connection connection = connectionFactory.newConnection();
	Channel channel = connection.createChannel();

3. 創建一個隊列，使用queueDeclareI(),至於各個參數可以自己測驗一下

	 /**
     * Declare a queue
     * @see com.rabbitmq.client.AMQP.Queue.Declare
     * @see com.rabbitmq.client.AMQP.Queue.DeclareOk
     * @param queue the name of the queue  隊列名稱，隨意寫
     * @param durable true if we are declaring a durable queue (the queue will survive a server restart) 是否持久化，true：持久化，就是重啓服務之後隊列任然存在，但是消息不回存在。
     * @param exclusive true if we are declaring an exclusive queue (restricted to this connection) 是否只有該創建這才能使用該隊列。
     * @param autoDelete true if we are declaring an autodelete queue (server will delete it when no longer in use) 當長時間沒有連接的時候是否自動刪除。
     * @param arguments other properties (construction arguments) for the queue 其他屬性 Map對象
     * @return a declaration-confirm method to indicate the queue was successfully declared
     * @throws java.io.IOException if an error is encountered
     */
	 channel.queueDeclare("queueName",true,false,false,null);

4. 創建一個Exchange 參數意思都差不多

	/**
     * 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  交換器的類型，常用的topic，和direct，fanout，其他的有headers，接下來會對其作解釋，並舉例，代碼說明
     * @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
     */
	 channel.exchangeDeclare("exchangeName","topic",true,false,null);

5. exchange創建玩成之後，需要將queue與exchange綁定。

	 /**
     * Bind a queue to an exchange, with no extra arguments.
     * @see com.rabbitmq.client.AMQP.Queue.Bind
     * @see com.rabbitmq.client.AMQP.Queue.BindOk
     * @param queue the name of the queue
     * @param exchange the name of the exchange
     * @param routingKey the routing 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
     */
	 channel.queueBind("queueName","exchangeName","routeKey");

6. 發送消息,並不需要指明隊列是哪個，只通過交換器和routeKey來發消息

	 /**
     * 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 props other properties for the message - routing headers etc
     * @param body the message body
     * @throws java.io.IOException if an error is encountered
     */
	 channel.basicPublish("exchange Name","routingKey", MessageProperties.TEXT_PLAIN,"hello world".getBytes());

7. 消費消息 主要注意的是Consumer，你可以自己定義一個類並實現Consumer接口。 通過void handleDelivery(String consumerTag,
   Envelope envelope,
   AMQP.BasicProperties properties,
   byte[] body)
   throws IOException; 該方法對隊列的消息進行其他的操作，body 消息內容。

	/**
     * Start a non-nolocal, non-exclusive consumer, with
     * explicit acknowledgement and a server-generated consumerTag.
     * @param queue the name of the queue
     * @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 #basicAck
     * @see #basicConsume(String, boolean, String, boolean, boolean, Map, Consumer)
     */
    String basicConsume(String queue, Consumer callback) throws IOException;

以上一個比較簡單的例子就完成了。接下來的文章將會對四種模式進行說明。