RabbitMQ routing模式
首先理解一下routing模式
原理同路由器,根据不同的rountKey可以指定发送到某一“IP”地址的接收者,例如发送者指定发送给IP为192.168.1.1的接收者。但是允许存在不同的接收者之间公用同一IP,即不同接收者允许有多个IP地址。
也可以多个queue绑定为同一routKey
还是先上代码
package com.tencent.routing; import com.rabbitmq.client.ConnectionFactory; import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; public class EmitLogDirect { private static final String EXCHANGE_NAME = "direct_logs"; public static void main(String[] argv) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setHost("localhost"); Connection connection = factory.newConnection(); Channel channel = connection.createChannel(); channel.exchangeDeclare(EXCHANGE_NAME, "direct"); String severity = getSeverity(argv); String message = getMessage(argv); channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes()); System.out.println(" [x] Sent '" + severity + "':'" + message + "'"); channel.close(); connection.close(); } private static String getSeverity(String[] strings){ if (strings.length < 1) return "info"; return strings[0]; } private static String getMessage(String[] strings){ if (strings.length < 2)//如果数据不够 则默认发送hello World return "Hello World!"; return joinStrings(strings, " ", 1); } private static String joinStrings(String[] strings, String delimiter, int startIndex) { int length = strings.length; if (length == 0 ) return ""; if (length < startIndex ) return ""; StringBuilder words = new StringBuilder(strings[startIndex]); for (int i = startIndex + 1; i < length; i++) { words.append(delimiter).append(strings[i]); } return words.toString(); } }
来看一下发送端producing端的代码,开始new了ConnectionFactory并open了相应的Connection和Channel.
关键代码出现了declare了一个Exchange
channel.exchangeDeclare(EXCHANGE_NAME, "direct");
exchange有direct, topic, headers 和 fanout这4种模式,fanout是在Publish/Subscribe模式下使用,即所有的queue都能接受到exchange分发的massage,
现在要讨论的routing模式,则采用的是direct(直发)模式。
然后channel在publish message的时候
channel.basicPublish(EXCHANGE_NAME, severity, null, message.getBytes());这里的severity对应的是下图中的'orange' ‘black’和'green' 也就是routKey
下图中有2个queue Q1和Q2 绑定(binding)到了exchange X上面
也就是说exchange决定了分发到哪个绑定了的queue
package com.tencent.routing; import com.rabbitmq.client.ConnectionFactory; import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; import com.rabbitmq.client.QueueingConsumer; public class ReceiveLogsDirect { private static final String EXCHANGE_NAME = "direct_logs"; public static void main(String[] argv) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setHost("localhost"); Connection connection = factory.newConnection(); Channel channel = connection.createChannel(); channel.exchangeDeclare(EXCHANGE_NAME, "direct"); String queueName = channel.queueDeclare().getQueue(); if (argv.length < 1){ System.err.println("Usage: ReceiveLogsDirect [info] [warning] [error]"); System.exit(1); } for(String severity : argv){ channel.queueBind(queueName, EXCHANGE_NAME, severity); //argv是用户的输入,指定这个Receive什么severity标签的数据 //argv指定error 该ReceivelLogDirect就只能接受binding到了error的Message } System.out.println(" [*] Waiting for messages. To exit press CTRL+C"); QueueingConsumer consumer = new QueueingConsumer(channel); channel.basicConsume(queueName, true, consumer); while (true) { QueueingConsumer.Delivery delivery = consumer.nextDelivery(); String message = new String(delivery.getBody()); String routingKey = delivery.getEnvelope().getRoutingKey(); System.out.println(" [x] Received '" + routingKey + "':'" + message + "'"); } } }
在consumer端,会为每一个severity创建一个新的绑定,也就是
for(String severity : argv)
channel.queueBind(queueName, EXCHAGNE_NAME ,severity)
参考 http://www.rabbitmq.com/tutorials/tutorial-four-java.html
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