1. 消息队列解决了什么问题

消息中间件是目前比较流行的一个中间件，其中RabbitMQ更是占有一定的市场份额，主要用来做异步处理、应用解耦、流量削峰、日志处理等等方面。

1. 异步处理

一个用户登陆网址注册，然后系统发短信跟邮件告知注册成功，一般有三种解决方法。

1. 串行到依次执行，问题是用户注册后就可以使用了，没必要等验证码跟邮件。

2. 注册成功后，邮件跟验证码用并行等方式执行，问题是邮件跟验证码是非重要的任务，系统注册还要等这俩完成么？

3. 基于异步MQ的处理，用户注册成功后直接把信息异步发送到MQ中，然后邮件系统跟验证码系统主动去拉取数据。

2. 应用解耦

比如我们有一个订单系统，还要一个库存系统，用户下订单了就要调用下库存系统来处理，直接调用到话库存系统出现问题咋办呢？

3. 流量削峰

举办一个 秒杀活动，如何较好到设计？服务层直接接受瞬间搞密度访问绝对不可以起码要加入一个MQ。

4. 日志处理

用户通过WebUI访问发送请求到时候后端如何接受跟处理呢一般？

2. RabbitMQ 安装跟配置

官网：https://www.rabbitmq.com/download.html

开发语言：https://www.erlang.org/

正式到安装跟允许需要Erlang跟RabbitMQ俩版本之间相互兼容！我这里图省事直接用Docker 拉取镜像了。下载：开启：管理页面 默认账号：guest  默认密码：guest 。Docker启动时候可以指定账号密码对外端口以及

docker run -d --hostname my-rabbit --name rabbit -e RABBITMQ_DEFAULT_USER=admin -e RABBITMQ_DEFAULT_PASS=admin -p 15672:15672 -p 5672:5672 -p 25672:25672 -p 61613:61613 -p 1883:1883 rabbitmq:management

启动：用户添加：vitrual hosts 相当于mysql中的DB。创建一个virtual hosts，一般以/ 开头。对用户进行授权，点击/vhost_mmr，至于WebUI多点点即可了解。

3. 实战

RabbitMQ 官网支持任务模式：https://www.rabbitmq.com/getstarted.htm

l创建Maven项目导入必要依赖：

    <dependencies><dependency><groupId>com.rabbitmq</groupId><artifactId>amqp-client</artifactId><version>4.0.2</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>1.7.10</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.7.5</version></dependency><dependency><groupId>log4j</groupId><artifactId>log4j</artifactId><version>1.2.17</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.11</version></dependency></dependencies>

0. 获取MQ连接

package com.sowhat.mq.util;import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class ConnectionUtils {/*** 连接器* @return* @throws IOException* @throws TimeoutException*/public static Connection getConnection() throws IOException, TimeoutException {ConnectionFactory factory = new ConnectionFactory();factory.setHost("127.0.0.1");factory.setPort(5672);factory.setVirtualHost("/vhost_mmr");factory.setUsername("user_mmr");factory.setPassword("sowhat");Connection connection = factory.newConnection();return connection;}
}

1. 简单队列

P:Producer 消息的生产者 中间：Queue消息队列 C:Consumer 消息的消费者

package com.sowhat.mq.simple;import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send {public static final String QUEUE_NAME = "test_simple_queue";public static void main(String[] args) throws IOException, TimeoutException {// 获取一个连接Connection connection = ConnectionUtils.getConnection();// 从连接获取一个通道Channel channel = connection.createChannel();// 创建队列声明AMQP.Queue.DeclareOk declareOk = channel.queueDeclare(QUEUE_NAME, false, false, false, null);String msg = "hello Simple";// exchange，队列，参数，消息字节体channel.basicPublish("", QUEUE_NAME, null, msg.getBytes());System.out.println("--send msg:" + msg);channel.close();connection.close();}
}
---
package com.sowhat.mq.simple;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;/*** 消费者获取消息*/
public class Recv {public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {newApi();oldApi();}private static void newApi() throws IOException, TimeoutException {// 创建连接Connection connection = ConnectionUtils.getConnection();// 创建频道Channel channel = connection.createChannel();// 队列声明  队列名，是否持久化，是否独占模式，无消息后是否自动删除，消息携带参数channel.queueDeclare(Send.QUEUE_NAME,false,false,false,null);// 定义消费者DefaultConsumer defaultConsumer = new DefaultConsumer(channel) {@Override  // 事件模型，消息来了会触发该函数public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("---new api recv:" + s);}};// 监听队列channel.basicConsume(Send.QUEUE_NAME,true,defaultConsumer);}// 老方法 消费者 MQ 在3。4以下 用次方法，private static void oldApi() throws IOException, TimeoutException, InterruptedException {// 创建连接Connection connection = ConnectionUtils.getConnection();// 创建频道Channel channel = connection.createChannel();// 定义队列消费者QueueingConsumer consumer = new QueueingConsumer(channel);//监听队列channel.basicConsume(Send.QUEUE_NAME, true, consumer);while (true) {// 发货体QueueingConsumer.Delivery delivery = consumer.nextDelivery();byte[] body = delivery.getBody();String s = new String(body);System.out.println("---Recv:" + s);}}
}

右上角有可以设置页面刷新频率，然后可以在UI界面直接手动消费掉，如下图：简单队列的不足：耦合性过高，生产者一一对应消费者，如果有多个消费者想消费队列中信息就无法实现了。

2. WorkQueue 工作队列

Simple队列中只能一一对应的生产消费，实际开发中生产者发消息很简单，而消费者要跟业务结合，消费者接受到消息后要处理从而会耗时。「可能会出现队列中出现消息积压」。所以如果多个消费者可以加速消费。

1. round robin 轮询分发

代码编程一个生产者两个消费者：

package com.sowhat.mq.work;import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send {public static final String  QUEUE_NAME = "test_work_queue";public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {// 获取连接Connection connection = ConnectionUtils.getConnection();// 获取 channelChannel channel = connection.createChannel();// 声明队列AMQP.Queue.DeclareOk declareOk = channel.queueDeclare(QUEUE_NAME, false, false, false, null);for (int i = 0; i <50 ; i++) {String msg = "hello-" + i;System.out.println("WQ send " + msg);channel.basicPublish("",QUEUE_NAME,null,msg.getBytes());Thread.sleep(i*20);}channel.close();connection.close();}
}---
package com.sowhat.mq.work;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv1 {public static void main(String[] args) throws IOException, TimeoutException {// 获取连接Connection connection = ConnectionUtils.getConnection();// 获取通道Channel channel = connection.createChannel();// 声明队列channel.queueDeclare(Send.QUEUE_NAME, false, false, false, null);//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【1】：" + s);try {Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【1】 done");}}};boolean autoAck = true;channel.basicConsume(Send.QUEUE_NAME, autoAck, consumer);}
}
---
package com.sowhat.mq.work;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv2 {public static void main(String[] args) throws IOException, TimeoutException {// 获取连接Connection connection = ConnectionUtils.getConnection();// 获取通道Channel channel = connection.createChannel();// 声明队列channel.queueDeclare(Send.QUEUE_NAME, false, false, false, null);//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【2】：" + s);try {Thread.sleep(1000 );} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【2】 done");}}};boolean autoAck = true;channel.basicConsume(Send.QUEUE_NAME, autoAck, consumer);}
}

现象：消费者1 跟消费者2 处理的数据量完全一样的个数：消费者1:处理偶数 消费者2:处理奇数 这种方式叫轮询分发(round-robin)结果就是不管两个消费者谁忙，「数据总是你一个我一个」，MQ 给两个消费发数据的时候是不知道消费者性能的，默认就是雨露均沾。此时 autoAck = true。

2. 公平分发 fair dipatch

如果要实现公平分发，要让消费者消费完毕一条数据后就告知MQ，再让MQ发数据即可。自动应答要关闭！

package com.sowhat.mq.work;import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send {public static final String  QUEUE_NAME = "test_work_queue";public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {// 获取连接Connection connection = ConnectionUtils.getConnection();// 获取 channelChannel channel = connection.createChannel();// s声明队列AMQP.Queue.DeclareOk declareOk = channel.queueDeclare(QUEUE_NAME, false, false, false, null);// 每个消费者发送确认消息之前，消息队列不发送下一个消息到消费者，一次只发送一个消息// 从而限制一次性发送给消费者到消息不得超过1个。int perfetchCount = 1;channel.basicQos(perfetchCount);for (int i = 0; i <50 ; i++) {String msg = "hello-" + i;System.out.println("WQ send " + msg);channel.basicPublish("",QUEUE_NAME,null,msg.getBytes());Thread.sleep(i*20);}channel.close();connection.close();}
}
---
package com.sowhat.mq.work;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv1 {public static void main(String[] args) throws IOException, TimeoutException {// 获取连接Connection connection = ConnectionUtils.getConnection();// 获取通道final Channel channel = connection.createChannel();// 声明队列channel.queueDeclare(Send.QUEUE_NAME, false, false, false, null);// 保证一次只分发一个channel.basicQos(1);//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【1】：" + s);try {Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【1】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(),false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(Send.QUEUE_NAME, autoAck, consumer);}
}
---
package com.sowhat.mq.work;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv2 {public static void main(String[] args) throws IOException, TimeoutException {// 获取连接Connection connection = ConnectionUtils.getConnection();// 获取通道final Channel channel = connection.createChannel();// 声明队列channel.queueDeclare(Send.QUEUE_NAME, false, false, false, null);// 保证一次只分发一个channel.basicQos(1);//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【2】：" + s);try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【2】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(),false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(Send.QUEUE_NAME, autoAck, consumer);}
}

结果：实现了公平分发，消费者2 是消费者1消费数量的2倍。

3. publish/subscribe 发布订阅模式

类似公众号的订阅跟发布，无需指定routingKey：

解读：

1. 一个生产者多个消费者

2. 每一个消费者都有一个自己的队列

3. 生产者没有把消息直接发送到队列而是发送到了交换机转化器(exchange)。

4. 每一个队列都要绑定到交换机上。

5. 生产者发送的消息经过交换机到达队列，从而实现一个消息被多个消费者消费。

生产者：

package com.sowhat.mq.ps;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send {public static final String EXCHANGE_NAME = "test_exchange_fanout";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();//声明交换机channel.exchangeDeclare(EXCHANGE_NAME,"fanout");// 分发= fanout// 发送消息String msg = "hello ps ";channel.basicPublish(EXCHANGE_NAME,"",null,msg.getBytes());System.out.println("Send:" + msg);channel.close();connection.close();}
}

消息哪儿去了？丢失了，在RabbitMQ中只有队列有存储能力，「因为这个时候队列还没有绑定到交换机 所以消息丢失了」。消费者：

package com.sowhat.mq.ps;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv1 {public static final String  QUEUE_NAME = "test_queue_fanout_email";public static final String EXCHANGE_NAME = "test_exchange_fanout";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();final Channel channel = connection.createChannel();// 队列声明channel.queueDeclare(QUEUE_NAME,false,false,false,null);// 绑定队列到交换机转发器channel.queueBind(QUEUE_NAME,EXCHANGE_NAME,"" );// 保证一次只分发一个channel.basicQos(1);//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【1】：" + s);try {Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【1】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(),false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(QUEUE_NAME, autoAck, consumer);}
}
---
package com.sowhat.mq.ps;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv2 {public static final String  QUEUE_NAME = "test_queue_fanout_sms";public static final String EXCHANGE_NAME = "test_exchange_fanout";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();final Channel channel = connection.createChannel();// 队列声明channel.queueDeclare(QUEUE_NAME,false,false,false,null);// 绑定队列到交换机转发器channel.queueBind(QUEUE_NAME,EXCHANGE_NAME,"" );// 保证一次只分发一个channel.basicQos(1);//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【2】：" + s);try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【2】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(),false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(QUEUE_NAME, autoAck, consumer);}
}

「同时还可以自己手动的添加一个队列监控到该exchange」

4. routing 路由选择 通配符模式

Exchange(交换机，转发器)：「一方面接受生产者消息，另一方面是向队列推送消息」。匿名转发用 ""  表示，比如前面到简单队列跟WorkQueue。fanout：不处理路由键。「不需要指定routingKey」，我们只需要把队列绑定到交换机， 「消息就会被发送到所有到队列中」。direct：处理路由键，「需要指定routingKey」，此时生产者发送数据到时候会指定key，任务队列也会指定key，只有key一样消息才会被传送到队列中。如下图

package com.sowhat.mq.routing;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send {public static final String  EXCHANGE_NAME = "test_exchange_direct";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();// exchangechannel.exchangeDeclare(EXCHANGE_NAME,"direct");String msg = "hello info!";// 可以指定类型String routingKey = "info";channel.basicPublish(EXCHANGE_NAME,routingKey,null,msg.getBytes());System.out.println("Send : " + msg);channel.close();connection.close();}
}
---
package com.sowhat.mq.routing;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv1 {public static final String  EXCHANGE_NAME = "test_exchange_direct";public static final String QUEUE_NAME = "test_queue_direct_1";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();final Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME,false,false,false,null);channel.basicQos(1);channel.queueBind(QUEUE_NAME,EXCHANGE_NAME,"error");//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【1】：" + s);try {Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【1】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(),false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(QUEUE_NAME, autoAck, consumer);}
}
---
package com.sowhat.mq.routing;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv2 {public static final String EXCHANGE_NAME = "test_exchange_direct";public static final String QUEUE_NAME = "test_queue_direct_2";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();final Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);channel.basicQos(1);// 绑定种类似 Keychannel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "error");channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "info");channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "warning");//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【2】：" + s);try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【2】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(), false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(QUEUE_NAME, autoAck, consumer);}
}

WebUI:缺点：路由key必须要明确，无法实现规则性模糊匹配。

5. Topics 主题

将路由键跟某个模式匹配，# 表示匹配 >=1个字符， *表示匹配一个。生产者会带routingKey，但是消费者的MQ会带模糊routingKey。商品：发布、删除、修改、查询。

package com.sowhat.mq.topic;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send {public static final String EXCHANGE_NAME = "test_exchange_topic";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();// exchangechannel.exchangeDeclare(EXCHANGE_NAME, "topic");String msg = "商品!";// 可以指定类型String routingKey = "goods.find";channel.basicPublish(EXCHANGE_NAME, routingKey, null, msg.getBytes());System.out.println("Send : " + msg);channel.close();connection.close();}
}
---
package com.sowhat.mq.topic;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv1 {public static final String  EXCHANGE_NAME = "test_exchange_topic";public static final String QUEUE_NAME = "test_queue_topic_1";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();final Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME,false,false,false,null);channel.basicQos(1);channel.queueBind(QUEUE_NAME,EXCHANGE_NAME,"goods.add");//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【1】：" + s);try {Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【1】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(),false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(QUEUE_NAME, autoAck, consumer);}
}
---
package com.sowhat.mq.topic;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv2 {public static final String EXCHANGE_NAME = "test_exchange_topic";public static final String QUEUE_NAME = "test_queue_topic_2";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();final Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);channel.basicQos(1);// 此乃重点channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "goods.#");//定义消费者DefaultConsumer consumer = new DefaultConsumer(channel) {@Override // 事件触发机制public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {String s = new String(body, "utf-8");System.out.println("【2】：" + s);try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();} finally {System.out.println("【2】 done");// 手动回执channel.basicAck(envelope.getDeliveryTag(), false);}}};// 自动应答boolean autoAck = false;channel.basicConsume(QUEUE_NAME, autoAck, consumer);}
}

6. MQ的持久化跟非持久化

因为消息在内存中，如果MQ挂了那么消息也丢失了，所以应该考虑MQ的持久化。MQ是支持持久化的，

// 声明队列
channel.queueDeclare(Send.QUEUE_NAME, false, false, false, null);/*** 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;

boolean durable就是表明是否可以持久化，如果我们将程序中的durable = false改为true是不可以的！因为我们已经定义过的test_work_queue，这个queue已声明为未持久化的。结论：MQ 不允许修改一个已经存在的队列参数。

7. 消费者端手动跟自动确认消息

// 自动应答boolean autoAck = false;channel.basicConsume(Send.QUEUE_NAME, autoAck, consumer);

当MQ发送数据个消费者后，消费者要对收到对信息应答给MQ。

如果autoAck = true 表示「自动确认模式」，一旦MQ把消息分发给消费者就会把消息从内存中删除。如果消费者收到消息但是还没有消费完而MQ中数据已删除则会导致丢失了正在处理对消息。

如果autoAck = false表示「手动确认模式」，如果有个消费者挂了，MQ因为没有收到回执信息可以把该信息再发送给其他对消费者。

MQ支持消息应答(Message acknowledgement)，消费者发送一个消息应答告诉MQ这个消息已经被消费了，MQ才从内存中删除。消息应答模式「默认为 false」。

8. RabbitMQ生产者端消息确认机制(事务 + confirm)

在RabbitMQ中我们可以通过持久化来解决MQ服务器异常的数据丢失问题，但是「生产者如何确保数据发送到MQ了」？默认情况下生产者也是不知道的。如何解决 呢？

1. AMQP事务

第一种方式AMQP实现了事务机制，类似mysql的事务机制。txSelect：用户将当前channel设置为transition模式。txCommit：用于提交事务。txRollback：用于回滚事务。

以上都是对生产者对操作。

package com.sowhat.mq.tx;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class TxSend {public static final String QUEUE_NAME = "test_queue_tx";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);String msg = "hello tx message";try {//开启事务模式channel.txSelect();channel.basicPublish("", QUEUE_NAME, null, msg.getBytes());int x = 1 / 0;// 提交事务channel.txCommit();} catch (IOException e) {// 回滚channel.txRollback();System.out.println("send message rollback");} finally {channel.close();connection.close();}}
}
---
package com.sowhat.mq.tx;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class TxRecv {public static final String QUEUE_NAME = "test_queue_tx";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);String s = channel.basicConsume(QUEUE_NAME, true, new DefaultConsumer(channel) {@Overridepublic void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {System.out.println("recv[tx] msg:" + new String(body, "utf-8"));}});channel.close();connection.close();}
}

缺点就是大量对请求尝试然后失败然后回滚，会降低MQ的吞吐量。

2. Confirm模式。

「生产者端confirm实现原理」生产者将信道设置为confirm模式，一旦信道进入了confirm模式，所以该信道上发布的信息都会被派一个唯一的ID(从1开始)，一旦消息被投递到所有的匹配队列后，Broker就回发送一个确认给生产者(包含消息唯一ID)，这就使得生产者知道消息已经正确到达目的队列了，如果消息跟队列是可持久化的，那么确认消息会在消息写入到磁盘后才发出。broker回传给生产者到确认消息中deliver-tag域包含了确认消息到序列号，此外broker也可以设置basic.ack的multiple域，表示这个序列号之前所以信息都已经得到处理。

Confirm模式最大的好处在于是异步的。第一条消息发送后不用一直等待回复后才发第二条消息。

开启confirm模式：channel.confimSelect()编程模式：

1. 普通的发送一个消息后就 waitForConfirms()

package com.sowhat.confirm;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send1 {public static final String QUEUE_NAME = "test_queue_confirm1";public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);// 将channel模式设置为 confirm模式，注意设置这个不能设置为事务模式。channel.confirmSelect();String msg = "hello confirm message";channel.basicPublish("", QUEUE_NAME, null, msg.getBytes());if (!channel.waitForConfirms()) {System.out.println("消息发送失败");} else {System.out.println("消息发送OK");}channel.close();connection.close();}
}
---
package com.sowhat.confirm;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Recv {public static final String QUEUE_NAME = "test_queue_confirm1";public static void main(String[] args) throws IOException, TimeoutException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);String s = channel.basicConsume(QUEUE_NAME, true, new DefaultConsumer(channel) {@Overridepublic void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {System.out.println("recv[tx] msg:" + new String(body, "utf-8"));}});}
}

2. 批量的发一批数据 waitForConfirms()

package com.sowhat.confirm;import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.concurrent.TimeoutException;public class Send2 {public static final String QUEUE_NAME = "test_queue_confirm1";public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);// 将channel模式设置为 confirm模式，注意设置这个不能设置为事务模式。channel.confirmSelect();String msg = "hello confirm message";// 批量发送for (int i = 0; i < 10; i++) {channel.basicPublish("", QUEUE_NAME, null, msg.getBytes());}// 确认if (!channel.waitForConfirms()) {System.out.println("消息发送失败");} else {System.out.println("消息发送OK");}channel.close();connection.close();}
}
---
接受信息跟上面一样

3. 异步confirm模式，提供一个回调方法。

Channel对象提供的ConfirmListener()回调方法只包含deliveryTag(包含当前发出消息序号)，我们需要自己为每一个Channel维护一个unconfirm的消息序号集合，每publish一条数据，集合中元素加1，每回调一次handleAck方法，unconfirm集合删掉响应的一条(multiple=false)或多条(multiple=true)记录，从运行效率来看，unconfirm集合最好采用有序集合SortedSet存储结构。

package com.sowhat.mq.confirm;import com.rabbitmq.client.*;
import com.sowhat.mq.util.ConnectionUtils;import java.io.IOException;
import java.util.Collections;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.TimeoutException;public class Send3 {public static final String QUEUE_NAME = "test_queue_confirm3";public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {Connection connection = ConnectionUtils.getConnection();Channel channel = connection.createChannel();channel.queueDeclare(QUEUE_NAME, false, false, false, null);//生产者调用confirmSelectchannel.confirmSelect();// 存放未确认消息final SortedSet<Long> confirmSet = Collections.synchronizedSortedSet(new TreeSet<Long>());// 添加监听通道channel.addConfirmListener(new ConfirmListener() {// 回执有问题的public void handleAck(long deliveryTag, boolean multiple) throws IOException {if (multiple) {System.out.println("--handleNack---multiple");confirmSet.headSet(deliveryTag + 1).clear();} else {System.out.println("--handleNack-- multiple false");confirmSet.remove(deliveryTag);}}// 没有问题的handleAckpublic void handleNack(long deliveryTag, boolean multiple) throws IOException {if (multiple) {System.out.println("--handleAck---multiple");confirmSet.headSet(deliveryTag + 1).clear();} else {System.out.println("--handleAck--multiple false");confirmSet.remove(deliveryTag);}}});// 一般情况下是先开启 消费者，指定好 exchange跟routingkey，如果生产者等routingkey 就会触发这个return 方法channel.addReturnListener(new ReturnListener() {public void handleReturn(int replyCode, String replyText, String exchange, String routingKey, AMQP.BasicProperties properties, byte[] body) throws IOException {System.out.println("---- handle return----");System.out.println("replyCode:" + replyCode );System.out.println("replyText:" +replyText );System.out.println("exchange:" + exchange);System.out.println("routingKey:" + routingKey);System.out.println("properties:" + properties);System.out.println("body:" + new String(body));}});String msgStr = "sssss";while(true){long nextPublishSeqNo = channel.getNextPublishSeqNo();channel.basicPublish("",QUEUE_NAME,null,msgStr.getBytes());confirmSet.add(nextPublishSeqNo);Thread.sleep(1000);}}
}

总结：AMQP模式相对来说没Confirm模式性能好些，推荐使用后者。

9. RabbitMQ延迟队列 跟死信

淘宝订单付款，验证码等限时类型服务。

        Map<String,Object> headers =  new HashMap<String,Object>();headers.put("my1","111");headers.put("my2","222");AMQP.BasicProperties build = new AMQP.BasicProperties().builder().deliveryMode(2).contentEncoding("utf-8").expiration("10000").headers(headers).build();

死信的处理：

10. SpringBoot Tpoic Demo

需求图：新建SpringBoot 项目添加如下依赖：

       <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-amqp</artifactId></dependency>

1. 生产者

application.yml

spring:rabbitmq:host: 127.0.0.1username: adminpassword: admin

测试用例：

package com.sowhat.mqpublisher;import org.junit.jupiter.api.Test;
import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;@SpringBootTest
class MqpublisherApplicationTests {@Autowiredprivate AmqpTemplate amqpTemplate;@Testvoid userInfo() {/*** exchange,routingKey,message*/this.amqpTemplate.convertAndSend("log.topic","user.log.error","Users...");}
}

2. 消费者

application.xml

spring:rabbitmq:host: 127.0.0.1username: adminpassword: admin# 自定义配置
mq:config:exchange_name: log.topic# 配置队列名称queue_name:info: log.infoerror: log.errorlogs: log.logs

三个不同的消费者：

package com.sowhat.mqconsumer.service;import org.springframework.amqp.core.ExchangeTypes;
import org.springframework.amqp.rabbit.annotation.Exchange;
import org.springframework.amqp.rabbit.annotation.Queue;
import org.springframework.amqp.rabbit.annotation.QueueBinding;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Service;/*** @QueueBinding value属性：用于绑定一个队列。@Queue去查找一个名字为value属性中的值得队列，如果没有则创建，如果有则返回* type = ExchangeTypes.TOPIC 指定交换器类型。默认的direct交换器*/
@Service
public class ErrorReceiverService {/*** 把一个方法跟一个队列进行绑定，收到消息后绑定给msg*/@RabbitListener(bindings = @QueueBinding(value = @Queue(value = "${mq.config.queue_name.error}"),exchange = @Exchange(value = "${mq.config.exchange_name}", type = ExchangeTypes.TOPIC),key = "*.log.error"))public void process(String msg) {System.out.println(msg + " Logs...........");}
}
---
package com.sowhat.mqconsumer.service;import org.springframework.amqp.core.ExchangeTypes;
import org.springframework.amqp.rabbit.annotation.Exchange;
import org.springframework.amqp.rabbit.annotation.Queue;
import org.springframework.amqp.rabbit.annotation.QueueBinding;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Service;/*** @QueueBinding value属性：用于绑定一个队列。* @Queue去查找一个名字为value属性中的值得队列，如果没有则创建，如果有则返回*/
@Service
public class InfoReceiverService {/*** 添加一个能够处理消息的方法*/@RabbitListener(bindings = @QueueBinding(value = @Queue(value ="${mq.config.queue_name.info}"),exchange = @Exchange(value = "${mq.config.exchange_name}",type = ExchangeTypes.TOPIC),key = "*.log.info"))public void process(String msg){System.out.println(msg+" Info...........");}
}
--
package com.sowhat.mqconsumer.service;import org.springframework.amqp.core.ExchangeTypes;
import org.springframework.amqp.rabbit.annotation.Exchange;
import org.springframework.amqp.rabbit.annotation.Queue;
import org.springframework.amqp.rabbit.annotation.QueueBinding;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.stereotype.Service;/*** @QueueBinding value属性：用于绑定一个队列。* @Queue去查找一个名字为value属性中的值得队列，如果没有则创建，如果有则返回*/
@Service
public class LogsReceiverService {/*** 添加一个能够处理消息的方法*/@RabbitListener(bindings = @QueueBinding(value = @Queue(value ="${mq.config.queue_name.logs}"),exchange = @Exchange(value = "${mq.config.exchange_name}",type = ExchangeTypes.TOPIC),key = "*.log.*"))public void process(String msg){System.out.println(msg+" Error...........");}
}

详细安装跟代码看参考下载：

总结

如果需要指定模式一般是在消费者端设置，灵活性调节。

模式	生产者Queue	生产者exchange	生产者routingKey	消费者exchange	消费者queue	routingKey
Simple(简单模式少用)	指定	不指定	不指定	不指定	指定	不指定
WorkQueue(多个消费者少用)	指定	不指定	不指定	不指定	指定	不指定
fanout(publish/subscribe模式)	不指定	指定	不指定	指定	指定	不指定
direct(路由模式)	不指定	指定	指定	指定	指定	消费者routingKey精确指定多个
topic(主题模糊匹配)	不指定	指定	指定	指定	指定	消费者routingKey可以进行模糊匹配

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