該知識來源於每特教育&螞蟻課堂 97後互聯網架構師-餘老師獨創講解<RabbitMQ解決分佈式事務>視頻教程內容文字和圖片都是來源於餘老師描述的話術和餘老師畫的圖片截圖

http://www.mayikt.com/front/couinfo/161/0#

案例分析

經典案例，以目前流行點外賣的案例，用戶下單後，調用訂單服務，讓後訂單服務調用派單系統通知送外賣人員送單，這時候訂單系統與派單系統採用MQ異步通訊， RabbitMQ解決分佈式事務原理：採用最終一致性原理。
MQ解決分佈式事務保證三大要素
1、確認生產者一定要將數據投遞到MQ服務器中（採用MQ消息確認機制）
2、MQ消費者消息能夠正確消費消息，採用手動ACK模式，使用不補償機制（注意重試冪等性問題）
3、如何保證第一個事務先執行，採用補償機制（補單機制），在創建一個補單消費者進行監聽，如果訂單沒有創建成功，進行補單。

疑問：用傳統的HTTP協議不能解決高併發，因爲是同步請求不能解決流量削峯問題，所以用MQ 解決高併發流量流量削峯問題。

MQ解決分佈式事務最終一致性思想

1. 確保生產者消息一定要投遞到MQ服務器端成功

2. 如果生產者投遞消息到MQ服務器成功
場景1 如果消費者消費消息失敗了
生產者是不需要回滾事務，消費者採用手動ack應答方式進行補償機制，補償的過程中注意冪等性問題，如何確保生產者發送消息一定發送到MQ消息服務器端成功呢？答案：就是採用 confirm機制確認應答機制
場景2 如果生產者發送消息到MQ服務器端失敗
使用生產者重試機制進行發消息

派件表：

create TABLE order_info(
  id INT PRIMARY KEY AUTO_INCREMENT,
  name VARCHAR(30),  
  order_money INT,
  orderId VARCHAR(255)
  
);

生產者

1.實現接口 implements RabbitTemplate.ConfirmCallback

2. 重寫回調方法成功失敗的調用

@Override
public void confirm(CorrelationData correlationData, boolean ack, String cause) {

send方法裏面調用回調函數：

this.rabbitTemplate.setMandatory(true);
this.rabbitTemplate.setConfirmCallback(this);

yml需要配置回調機制：

###開啓消息確認機制 confirms
publisher-confirms: true
publisher-returns: true

重試也是有一定次數限制的如果超過一定次數就需要進行人工補償了

上面已經實現了確保消息發送給消費者此時的數據不一致問題就是：

場景3. 如何保證第一個事務先執行，生產者投遞消息到MQ服務器成功，消費者消費消息成功了，但是訂單事務回滾了。（生產者投遞消息給消費者消費成功然後生產者回滾了）

MQ解決分佈式原理通過最終一致性解決總體框架圖：交換機採用路由鍵模式補單隊列和派但隊列都綁定同一個路由鍵

基礎包：

public interface ApiConstants {
    // 響應請求成功
    String HTTP_RES_CODE_200_VALUE = "success";
    // 系統錯誤
    String HTTP_RES_CODE_500_VALUE = "fial";
    // 響應請求成功code
    Integer HTTP_RES_CODE_200 = 200;
    // 系統錯誤
    Integer HTTP_RES_CODE_500 = 500;
    // 未關聯QQ賬號
    Integer HTTP_RES_CODE_201 = 201;

}

import org.springframework.stereotype.Component;

@Component
public class BaseApiService {

    public ResponseBase setResultError(Integer code, String msg) {
        return setResult(code, msg, null);
    }

    // 返回錯誤，可以傳msg
    public ResponseBase setResultError(String msg) {
        return setResult(ApiConstants.HTTP_RES_CODE_500, msg, null);
    }

    // 返回成功，可以傳data值
    public ResponseBase setResultSuccess(Object data) {
        return setResult(ApiConstants.HTTP_RES_CODE_200, ApiConstants.HTTP_RES_CODE_200_VALUE, data);
    }

    // 返回成功，沒有data值
    public ResponseBase setResultSuccess() {
        return setResult(ApiConstants.HTTP_RES_CODE_200, ApiConstants.HTTP_RES_CODE_200_VALUE, null);
    }

    // 返回成功，沒有data值
    public ResponseBase setResultSuccess(String msg) {
        return setResult(ApiConstants.HTTP_RES_CODE_200, msg, null);
    }

    // 通用封裝
    public ResponseBase setResult(Integer code, String msg, Object data) {
        return new ResponseBase(code, msg, data);
    }

}

補償隊列：

import lombok.Data;

@Data
public class ResponseBase {

    private Integer rtnCode;
    private String msg;
    private Object data;

    public ResponseBase() {

    }

    public ResponseBase(Integer rtnCode, String msg, Object data) {
        super();
        this.rtnCode = rtnCode;
        this.msg = msg;
        this.data = data;
    }

    @Override
    public String toString() {
        return "ResponseBase [rtnCode=" + rtnCode + ", msg=" + msg + ", data=" + data + "]";
    }

}

entity：

import lombok.Data;

@Data
public class OrderEntity {

    private Long id;
    // 訂單名稱
    private String name;
    // 下單金額
    private Double orderMoney;
    // 訂單id
    private String orderId;
}

mapper：

import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Options;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import com.mayikt.entity.OrderEntity;

public interface OrderMapper {

    @Insert(value = "INSERT INTO `order_info` VALUES (#{id}, #{name}, #{orderMoney},#{orderId})")
    @Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "id")
    public int addOrder(OrderEntity orderEntity);

    @Select("SELECT id as id ,name as name , order_money as orderMoney,orderId as orderId from order_info where orderId=#{orderId};")
    public OrderEntity findOrderId(@Param("orderId") String orderId);

}

MQ的配置：

import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.DirectExchange;
import org.springframework.amqp.core.DirectExchange;
import org.springframework.amqp.core.FanoutExchange;
import org.springframework.amqp.core.Queue;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;

@Component
public class RabbitmqConfig {

    // 下單並且派單存隊列
    public static final String ORDER_DIC_QUEUE = "order_dic_queue";
    // 補單隊列，判斷訂單是否已經被創建
    public static final String ORDER_CREATE_QUEUE = "order_create_queue";
    // 下單並且派單交換機
    private static final String ORDER_EXCHANGE_NAME = "order_exchange_name";

    // 1.定義訂單隊列
    @Bean
    public Queue directOrderDicQueue() {
        return new Queue(ORDER_DIC_QUEUE);
    }

    // 2.定義補訂單隊列
    @Bean
    public Queue directCreateOrderQueue() {
        return new Queue(ORDER_CREATE_QUEUE);
    }

    // 2.定義交換機
    @Bean
    DirectExchange directOrderExchange() {
        return new DirectExchange(ORDER_EXCHANGE_NAME);
    }

    // 3.訂單隊列與交換機綁定
    @Bean
    Binding bindingExchangeOrderDicQueue() {
        return BindingBuilder.bind(directOrderDicQueue()).to(directOrderExchange()).with("orderRoutingKey");
    }

    // 3.補單隊列與交換機綁定
    @Bean
    Binding bindingExchangeCreateOrder() {
        return BindingBuilder.bind(directCreateOrderQueue()).to(directOrderExchange()).with("orderRoutingKey");
    }

}

service：

import java.util.UUID;

import org.springframework.amqp.core.Message;
import org.springframework.amqp.core.MessageBuilder;
import org.springframework.amqp.core.MessageProperties;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.amqp.rabbit.support.CorrelationData;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.alibaba.fastjson.JSONObject;
import com.mayikt.base.BaseApiService;
import com.mayikt.base.ResponseBase;
import com.mayikt.entity.OrderEntity;
import com.mayikt.mapper.OrderMapper;

@Service
public class OrderService extends BaseApiService implements RabbitTemplate.ConfirmCallback {
    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private RabbitTemplate rabbitTemplate;

    public ResponseBase addOrderAndDispatch() {
        //先下單 訂單表插入數據
        OrderEntity orderEntity = new OrderEntity();
        orderEntity.setName("黃燜雞米飯");
        // 價格是300元
        orderEntity.setOrderMoney(300d);
        // 商品id
        String orderId = UUID.randomUUID().toString();
        orderEntity.setOrderId(orderId);
        // 1.先下單，創建訂單 (往訂單數據庫中插入一條數據)
        int orderResult = orderMapper.addOrder(orderEntity);
        System.out.println("orderResult:" + orderResult);
        if (orderResult <= 0) {
            return setResultError("下單失敗!");
        }
        // 2.訂單表插插入完數據後 訂單表發送 外賣小哥
        send(orderId);
    //    int i = 1/0;   //發生異常
        return setResultSuccess();
    }

    private void send(String orderId) {
        JSONObject jsonObect = new JSONObject();
        jsonObect.put("orderId", orderId);
        String msg = jsonObect.toJSONString();
        System.out.println("msg:" + msg);
        // 封裝消息
        Message message = MessageBuilder.withBody(msg.getBytes()).setContentType(MessageProperties.CONTENT_TYPE_JSON)
                .setContentEncoding("utf-8").setMessageId(orderId).build();
        // 構建回調返回的數據
        CorrelationData correlationData = new CorrelationData(orderId);
        // 發送消息
        this.rabbitTemplate.setMandatory(true);
        this.rabbitTemplate.setConfirmCallback(this);
        rabbitTemplate.convertAndSend("order_exchange_name", "orderRoutingKey", message, correlationData);

    }

    // 生產消息確認機制 生產者往服務器端發送消息的時候 採用應答機制
    @Override
    public void confirm(CorrelationData correlationData, boolean ack, String cause) {
        String orderId = correlationData.getId(); //id 都是相同的哦  全局ID
        System.out.println("消息id:" + correlationData.getId()); 
        if (ack) { //消息發送成功
            System.out.println("消息發送確認成功");
        } else {
            //重試機制
            send(orderId); 
            System.out.println("消息發送確認失敗:" + cause);
        }

    }

}

controller：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.mayikt.base.BaseApiService;
import com.mayikt.base.ResponseBase;
import com.mayikt.service.OrderService;

@RestController
public class OrderController extends BaseApiService {
    @Autowired
    private OrderService orderService;

    @RequestMapping("/addOrder")
    public ResponseBase addOrder() {
        return orderService.addOrderAndDispatch();
    }

}

yml：

spring:
  rabbitmq:
  ####連接地址
    host: 192.168.91.6
   ####端口號   
    port: 5672
   ####賬號 
    username: admin
   ####密碼  
    password: admin
   ### 地址
    virtual-host: /admin_toov5
    ###開啓消息確認機制 confirms
    publisher-confirms: true
    publisher-returns: true 
  #數據庫連接信息
  datasource: 
        name: test
        url: jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf8&autoReconnect=true&rewriteBatchedStatements=TRUE
        username: root
        password: root
        # 使用druid數據源
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.jdbc.Driver

啓動類：

package com.mayikt;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("com.mayikt.mapper")
@SpringBootApplication
public class AppOrder {

    public static void main(String[] args) {
        SpringApplication.run(AppOrder.class, args);
    }

}

派單：

Entity:

package com.mayikt.entity;

import lombok.Data;

@Data
public class DispatchEntity {

    private Long id;
    // 訂單號
    private String orderId;
    // 外賣員id
    private Long takeoutUserId;
    
}

Mapper:

package com.mayikt.mapper;

import org.apache.ibatis.annotations.Insert;

import com.mayikt.entity.DispatchEntity;

public interface DispatchMapper {

    /**
     * 新增派單任務
     */
    @Insert("INSERT into platoon values (null,#{orderId},#{takeoutUserId});")
    public int insertDistribute(DispatchEntity distributeEntity);

}

consumer:

做一些路由器隊列路由鍵的綁定聲明工作

package com.mayikt.rabbitmq.consumer;

import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.DirectExchange;
import org.springframework.amqp.core.DirectExchange;
import org.springframework.amqp.core.FanoutExchange;
import org.springframework.amqp.core.Queue;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;

@Component
public class RabbitmqConfig {

    // 下單並且派單存隊列
    public static final String ORDER_DIC_QUEUE = "order_dic_queue";
    // 補單隊列，判斷訂單是否已經被創建
    public static final String ORDER_CREATE_QUEUE = "order_create_queue";
    // 下單並且派單交換機
    private static final String ORDER_EXCHANGE_NAME = "order_exchange_name";

    // 1.定義派單隊列
    @Bean
    public Queue OrderDicQueue() {
        return new Queue(ORDER_DIC_QUEUE);
    }
/*
    // 2.定義補訂單隊列
    @Bean
    public Queue directCreateOrderQueue() {
        return new Queue(ORDER_CREATE_QUEUE);
    }*/

    // 2.定義交換機
    @Bean
    DirectExchange directOrderExchange() {
        return new DirectExchange(ORDER_EXCHANGE_NAME);
    }

    // 3.訂單隊列與交換機綁定
    @Bean
    Binding bindingExchangeOrderDicQueue() {
        return BindingBuilder.bind(OrderDicQueue()).to(directOrderExchange()).with("orderRoutingKey");
    }

    /*// 3.補單隊列與交換機綁定
    @Bean
    Binding bindingExchangeCreateOrder() {
        return BindingBuilder.bind(OrderDicQueue()).to(directOrderExchange()).with("orderRoutingKey");
    }*/

}

派件消費：

package com.mayikt.rabbitmq.consumer;

import java.util.Map;

import org.apache.commons.lang3.StringUtils;
import org.springframework.amqp.core.Message;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.messaging.handler.annotation.Headers;
import org.springframework.stereotype.Component;

import com.alibaba.fastjson.JSONObject;
import com.mayikt.entity.DispatchEntity;
import com.mayikt.mapper.DispatchMapper;
import com.rabbitmq.client.Channel;

/**
 * 派單服務
 */
@Component
public class DispatchConsumer {
    @Autowired
    private DispatchMapper dispatchMapper;

    @RabbitListener(queues = "order_dic_queue")
    public void process(Message message, @Headers Map<String, Object> headers, Channel channel) throws Exception {
        String messageId = message.getMessageProperties().getMessageId();
        String msg = new String(message.getBody(), "UTF-8");
        System.out.println("派單服務平臺" + msg + ",消息id:" + messageId);
        JSONObject jsonObject = JSONObject.parseObject(msg);
        String orderId = jsonObject.getString("orderId");
        if (StringUtils.isEmpty(orderId)) {
            // 日誌記錄
            return;
        }
        DispatchEntity dispatchEntity = new DispatchEntity();
        // 訂單id
        dispatchEntity.setOrderId(orderId);
        // 外賣員id
        dispatchEntity.setTakeoutUserId(12l);
        
        try {
            int insertDistribute = dispatchMapper.insertDistribute(dispatchEntity);
            if (insertDistribute > 0) {
                // 手動簽收消息,通知mq服務器端刪除該消息
                channel.basicAck(message.getMessageProperties().getDeliveryTag(), false);
            }
        } catch (Exception e) {
            e.printStackTrace();
            // // 丟棄該消息
            channel.basicNack(message.getMessageProperties().getDeliveryTag(), false, false);
        }
    }

}

啓動類：

package com.mayikt;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("com.mayikt.mapper")
@SpringBootApplication
public class AppDispatch {

    public static void main(String[] args) {
        SpringApplication.run(AppDispatch.class, args);
    }

}

yml：

spring:
  rabbitmq:
  ####連接地址
    host: 192.168.91.6
   ####端口號   
    port: 5672
   ####賬號 
    username: admin
   ####密碼  
    password: admin
   ### 地址
    virtual-host: /admin_toov5
    listener:
      simple:
        retry:
        ####開啓消費者（程序出現異常的情況下會）進行重試
          enabled: true
         ####最大重試次數
          max-attempts: 5
        ####重試間隔次數
          initial-interval: 3000
        ####開啓手動ack  
        acknowledge-mode: manual
         
  #數據庫連接信息
  datasource: 
        name: test
        url: jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf8&autoReconnect=true&rewriteBatchedStatements=TRUE
        username: root
        password: root
        # 使用druid數據源
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.jdbc.Driver
server:
  port: 8081

pom：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.itmayiedu</groupId>
    <artifactId>rabbitmq_stock</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
    </parent>
    <dependencies>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <!-- mysql 依賴 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!-- 阿里巴巴數據源 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.14</version>
        </dependency>
        <!-- SpringBoot整合Web組件 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- springboot- 整個 lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <!-- 添加springboot對amqp的支持 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-amqp</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </dependency>
        <!--fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.49</version>
        </dependency>
    </dependencies>
</project>

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