最终一致性解决方案一：消息队列+本地事件表

消息队列+事件表

不适用数据量特别大的情况，可以在中小型系统中应用

流程图

通过消息事件id，主键约束，来保证消息重复消费的问题

项目演示

• service-order 生产端（定时任务存信息到activemq）

• service-pay 消费端(监听者在activemq取数据)

启动activemq

activemq.xml中配置死信队列

<destinationPolicy>
	<policyMap>
	  <policyEntries>
		<!--死信队列-->
		<policyEntry queue=">">  
			<deadLetterStrategy>  
				<individualDeadLetterStrategy queuePrefix="DLQ."  
				  useQueueForQueueMessages="true" processNonPersistent="true" />  
			</deadLetterStrategy>  
		</policyEntry>
		
		<policyEntry topic=">" >
			<!-- The constantPendingMessageLimitStrategy is used to prevent
				 slow topic consumers to block producers and affect other consumers
				 by limiting the number of messages that are retained
				 For more information, see:

				 http://activemq.apache.org/slow-consumer-handling.html

			-->
		  <pendingMessageLimitStrategy>
			<constantPendingMessageLimitStrategy limit="1000"/>
		  </pendingMessageLimitStrategy>
		</policyEntry>
	  </policyEntries>
	</policyMap>
</destinationPolicy>

启动过程中可能出现的错误

activemq 启动时出现错误 Address already in use: JVM_Bind

pom.xml

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

<!--activemq pool-->
<dependency>
    <groupId>org.apache.activemq</groupId>
    <artifactId>activemq-pool</artifactId>
</dependency>

application.yml

server:
  port: 5001

spring:
  application:
    name: service-order
  activemq:
    broker-url: tcp://127.0.0.1:61616
    user: admin
    password: admin
    pool:
      enabled: true
      max-connections: 100

  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://192.168.1.113:3306/service-order?characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
    username: root
    password: 123456
    dbcp2:
      initial-size: 5
      min-idle: 5
      max-total: 5
      max-wait-millis: 200
      validation-query: SELECT 1
      test-while-idle: true
      test-on-borrow: false
      test-on-return: false

mybatis:
  mapper-locations:
    - classpath:mapper/*.xml

启动类

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.jms.annotation.EnableJms;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
@EnableJms
public class ServiceOrderApplication {
    public static void main(String[] args) {
        SpringApplication.run(ServiceOrderApplication.class, args);
    }
}

生产端代码 service-order

ActiveMQConfig配置类

import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.command.ActiveMQQueue;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.jms.Queue;

/**
 * 消息生产端的配置
 */

@Configuration
public class ActiveMQConfig {

    @Value("${spring.activemq.broker-url}")
    private String brokerUrl;

    @Bean
    public Queue queue() {
        return new ActiveMQQueue("ActiveMQQueue");
    }

    @Bean
    public ActiveMQConnectionFactory connectionFactory(){
        return new ActiveMQConnectionFactory(brokerUrl);
    }
}

定时任务

import com.dandan.serviceorder.dao.TblOrderEventDao;
import com.dandan.serviceorder.entity.TblOrderEvent;
import net.sf.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jms.core.JmsMessagingTemplate;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

import javax.jms.Queue;
import java.util.List;

@Component
public class ProduceTask {
    @Autowired
    private TblOrderEventDao tblOrderEventDao;

    @Autowired
    private Queue queue;

    @Autowired
    JmsMessagingTemplate jmsMessagingTemplate;

    @Scheduled(cron="0/5 * * * * ?")
    @Transactional(rollbackFor = Exception.class)
    public void task(){
        System.out.println("定时任务");

        List<TblOrderEvent> tblOrderEventList = tblOrderEventDao.selectByOrderType("1");
        for (int i = 0; i < tblOrderEventList.size(); i++) {
            TblOrderEvent event = tblOrderEventList.get(i);

            // 更改这条数据的orderType为2
            tblOrderEventDao.updateEvent(event.getOrderType());
            System.out.println("修改数据库完成");

            jmsMessagingTemplate.convertAndSend(queue,JSONObject.fromObject(event).toString());

        }
    }
}

事件表sql

CREATE TABLE `tbl_order_event` (
   `id` int(20) NOT NULL,
   `order_type` varchar(10) DEFAULT NULL,
   `process` varchar(255) DEFAULT NULL,
   `content` varchar(255) DEFAULT NULL,
   `create_time` datetime DEFAULT NULL,
   `update_time` datetime DEFAULT NULL,
   PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

消费端代码 service-pay

消息消费端的配置

import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.RedeliveryPolicy;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jms.config.DefaultJmsListenerContainerFactory;
import org.springframework.jms.config.JmsListenerContainerFactory;

/**
 * 消息消费端的配置
 */
@Configuration
public class ActiveMQConfig {

    @Value("${spring.activemq.broker-url}")
    private String brokerUrl;

    /**
     * 连接工厂
     * @param redeliveryPolicy
     * @return
     */
    @Bean
    public ActiveMQConnectionFactory connectionFactory(RedeliveryPolicy redeliveryPolicy){
        ActiveMQConnectionFactory activeMQConnectionFactory = new ActiveMQConnectionFactory("admin","admin",brokerUrl);
        activeMQConnectionFactory.setRedeliveryPolicy(redeliveryPolicy);
        return activeMQConnectionFactory;
    }

    /**
     * 重发配置
     * @return
     */
    @Bean
    public RedeliveryPolicy redeliveryPolicy(){
        RedeliveryPolicy redeliveryPolicy = new RedeliveryPolicy();
        return redeliveryPolicy;
    }

    /**
     * 设置消息队列 确认机制
     * @param activeMQConnectionFactory
     * @return
     */
    @Bean
    public JmsListenerContainerFactory jmsListenerContainerFactory(ActiveMQConnectionFactory activeMQConnectionFactory){
        DefaultJmsListenerContainerFactory bean = new DefaultJmsListenerContainerFactory();
        bean.setConnectionFactory(activeMQConnectionFactory);
        // 1: 自动确认，2： 客户端手动确认，3：自动批量确认，4 事务提交并确认。
        bean.setSessionAcknowledgeMode(2);
        return bean;
    }
}

消息监听

import com.dandan.servicepay.dao.TblOrderEventDao;
import com.dandan.servicepay.entity.TblOrderEvent;
import net.sf.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jms.annotation.JmsListener;
import org.springframework.stereotype.Component;

import javax.jms.JMSException;
import javax.jms.Session;
import javax.jms.TextMessage;

/**
 * 消息监听
 */
@Component
public class ConsumerQueue {

    @Autowired
    private TblOrderEventDao tblOrderEventDao;

    @JmsListener(destination = "ActiveMQQueue",containerFactory = "jmsListenerContainerFactory")
    public void receive(TextMessage textMessage, Session session) throws JMSException {
        try {
            System.out.println("收到的消息："+textMessage.getText());
            String content = textMessage.getText();

            TblOrderEvent tblOrderEvent = (TblOrderEvent) JSONObject.toBean(JSONObject.fromObject(content),TblOrderEvent.class);
            tblOrderEventDao.insert(tblOrderEvent);
            // 业务完成，确认消息 消费成功
            textMessage.acknowledge();
        }catch (Exception e){
            // 回滚消息
            e.printStackTrace();
//            e.getMessage(); // 放到log中。
            System.out.println("异常了");
            //恢复数据到消息队列
            session.recover();
        }

    }

    /**
     * mq中消息被消费6次都没有收到ack，就进入死信队列
     *
     * 补偿 处理（人工，脚本）。自己根据自己情况。
     * @param text
     */
    @JmsListener(destination = "DLQ.ActiveMQQueue")
    public void receive2(String text){
        System.out.println("死信队列:"+text);
    }
}