java exchangedeclare_RabbitMq之备份交换机（alternate-exchange）

备份交换器，AlternateExchange(AE)；

备份交换器是为了实现没有路由到队列的消息，声明交换机的时候添加属性alternate-exchange，声明一个备用交换机，一般声明为fanout类型，这样交换机收到路由不到队列的消息就会发送到备用交换机绑定的队列中。

package com.sky.study.alternate;

import java.io.IOException;

import java.nio.charset.StandardCharsets;

import java.text.SimpleDateFormat;

import java.util.Date;

import java.util.HashMap;

import java.util.Map;

import com.rabbitmq.client.Channel;

import com.rabbitmq.client.Connection;

import com.rabbitmq.client.MessageProperties;

import com.sky.study.ConnectionUtil;

public class RabbitProducer {

private static final String EXCHANGE_NAME = "exchange_demo";

private static final String BINDING_KEY = "bingkey_demo";

private static final String QUEUE_NAME = "queue_demo";

public static void main(String[] args) throws Exception {

try {

// 创建一个连接

Connection connection = ConnectionUtil.getConnection();

// 创建信道

Channel channel = connection.createChannel();

Map arguments = new HashMap<>(16);

arguments.put("alternate-exchange", "backup-exchange");

channel.exchangeDeclare(EXCHANGE_NAME, "direct", true, false, arguments);

channel.queueDeclare(QUEUE_NAME, true, false, false, null);

channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, BINDING_KEY);

// 声明一个 fanout 类型的交换器，建议此处使用 fanout 类型的交换器

channel.exchangeDeclare("backup-exchange", "fanout", true, false, null);

// 消息没有被路由的之后存入的队列

channel.queueDeclare("unRoutingQueue", true, false, false, null);

channel.queueBind("unRoutingQueue", "backup-exchange", "");

// 发送一条持久化消息

String message = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()) + " 没有被正确的路由到消息队列，此时此消息会进入 unRoutingQueue";

try {

// 使用 routingKey

channel.basicPublish(EXCHANGE_NAME, "not-exists-routing-key", true, MessageProperties.PERSISTENT_TEXT_PLAIN, message.getBytes(StandardCharsets.UTF_8));

System.err.println("消息发送完成......");

} catch (IOException e) {

e.printStackTrace();

}

}catch (Exception e) {

e.printStackTrace();

}

}

}