Spring Cloud Alibaba 系列之 Seata 分布式事务 demo

ゝ一世哀愁。 2022-12-26 02:22 158阅读 0赞

## 1.1 概述 ##

在上一篇博客 [《Spring Cloud Alibaba 系列之 Seata 介绍》][Spring Cloud Alibaba _ Seata] 介绍了 Seata，在这一篇中我们来看看怎么使用。以一个用户购买商品的微服务示例开始，整个业务逻辑由3个微服务提供支持：仓储服务：对给定的商品扣除仓储数量。订单服务：根据采购需求创建订单。帐户服务：从用户帐户中扣除余额。

![在这里插入图片描述][20201203093203866.png_pic_center]

## 1.2 创建模块 ##

### ☞ 创建数据库 ###

每一个服务都对应自己的数据库，这里使用 JPA 自动创建表，另外每个库都需要单独的回滚日志表，建表语句如下。

CREATE TABLE `undo_log` (
      `id` bigint(20) NOT NULL AUTO_INCREMENT,
      `branch_id` bigint(20) NOT NULL,
      `xid` varchar(100) NOT NULL,
      `context` varchar(128) NOT NULL,
      `rollback_info` longblob NOT NULL,
      `log_status` int(11) NOT NULL,
      `log_created` datetime NOT NULL,
      `log_modified` datetime NOT NULL,
      `ext` varchar(100) DEFAULT NULL,
      PRIMARY KEY (`id`),
      UNIQUE KEY `ux_undo_log` (`xid`,`branch_id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

### ☞ 相关依赖 ###

<properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.3.4.RELEASE</spring-boot.version>
        <spring-cloud-alibaba.version>2.2.2.RELEASE</spring-cloud-alibaba.version>
        <spring-cloud.version>Hoxton.SR8</spring-cloud.version>
    </properties>
    
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
    </dependencies>
    
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>${spring-cloud-alibaba.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

### ☞ 配置文件 ###

除了添加 application.yml 以外还需要添加 file.conf 以及 registry.conf 两个文件

# application.yml
    server:
      port: 8081
    
    spring:
      application:
        name: order-server
      cloud:
        alibaba:
          seata:
            # 自定义事务组名称需要与 seata-server 中的对应
            tx-service-group: my_seata_tx_group
        nacos:
          discovery:
            # 服务端地址
            server-addr: 127.0.0.1:8848
      datasource:
        # mysql 驱动 6.0 以上使用如下配置
        driverClassName: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://127.0.0.1:3306/order?serverTimezone=UTC
        username: root
        password: root
      jpa:
        database: MySQL
        show-sql: true
        generate-ddl: true
        hibernate:
          ddl-auto: update # 没有表创建表，有表更新表
          naming:
            physical-strategy: org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy  # 命名策略

# file.conf
    transport { 
      # tcp udt unix-domain-socket
      type = "TCP"
      #NIO NATIVE
      server = "NIO"
      #enable heartbeat
      heartbeat = true
      # the client batch send request enable
      enableClientBatchSendRequest = true
      #thread factory for netty
      threadFactory { 
        bossThreadPrefix = "NettyBoss"
        workerThreadPrefix = "NettyServerNIOWorker"
        serverExecutorThread-prefix = "NettyServerBizHandler"
        shareBossWorker = false
        clientSelectorThreadPrefix = "NettyClientSelector"
        clientSelectorThreadSize = 1
        clientWorkerThreadPrefix = "NettyClientWorkerThread"
        # netty boss thread size,will not be used for UDT
        bossThreadSize = 1
        #auto default pin or 8
        workerThreadSize = "default"
      }
      shutdown { 
        # when destroy server, wait seconds
        wait = 3
      }
      serialization = "seata"
      compressor = "none"
    }
    service { 
      #transaction service group mapping
      #
      # 改成对应的, 与添加到 nacos 的保持一致
      #
      vgroupMapping.my_seata_tx_group = "default"
      #only support when registry.type=file, please don't set multiple addresses
      default.grouplist = "127.0.0.1:8091"
      #degrade, current not support
      enableDegrade = false
      #disable seata
      disableGlobalTransaction = false
    }
    
    client { 
      rm { 
        asyncCommitBufferLimit = 10000
        lock { 
          retryInterval = 10
          retryTimes = 30
          retryPolicyBranchRollbackOnConflict = true
        }
        reportRetryCount = 5
        tableMetaCheckEnable = false
        reportSuccessEnable = false
        sagaBranchRegisterEnable = false
      }
      tm { 
        commitRetryCount = 5
        rollbackRetryCount = 5
        degradeCheck = false
        degradeCheckPeriod = 2000
        degradeCheckAllowTimes = 10
      }
      undo { 
        dataValidation = true
        onlyCareUpdateColumns = true
        logSerialization = "jackson"
        logTable = "undo_log"
      }
      log { 
        exceptionRate = 100
      }
    }

# registry.conf
    registry { 
      # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
      type = "nacos"
      loadBalance = "RandomLoadBalance"
      loadBalanceVirtualNodes = 10
    
      nacos { 
        application = "seata-server"
        serverAddr = "127.0.0.1:8848"
        group = "SEATA_GROUP"
        namespace = ""
        cluster = "default"
        username = ""
        password = ""
      }
      eureka { 
        serviceUrl = "http://localhost:8761/eureka"
        application = "default"
        weight = "1"
      }
      redis { 
        serverAddr = "localhost:6379"
        db = 0
        password = ""
        cluster = "default"
        timeout = 0
      }
      zk { 
        cluster = "default"
        serverAddr = "127.0.0.1:2181"
        sessionTimeout = 6000
        connectTimeout = 2000
        username = ""
        password = ""
      }
      consul { 
        cluster = "default"
        serverAddr = "127.0.0.1:8500"
      }
      etcd3 { 
        cluster = "default"
        serverAddr = "http://localhost:2379"
      }
      sofa { 
        serverAddr = "127.0.0.1:9603"
        application = "default"
        region = "DEFAULT_ZONE"
        datacenter = "DefaultDataCenter"
        cluster = "default"
        group = "SEATA_GROUP"
        addressWaitTime = "3000"
      }
      file { 
        name = "file.conf"
      }
    }
    
    config { 
      # file、nacos 、apollo、zk、consul、etcd3
      type = "file"
    
      nacos { 
        serverAddr = "127.0.0.1:8848"
        namespace = ""
        group = "SEATA_GROUP"
        username = ""
        password = ""
      }
      consul { 
        serverAddr = "127.0.0.1:8500"
      }
      apollo { 
        appId = "seata-server"
        apolloMeta = "http://192.168.1.204:8801"
        namespace = "application"
        apolloAccesskeySecret = ""
      }
      zk { 
        serverAddr = "127.0.0.1:2181"
        sessionTimeout = 6000
        connectTimeout = 2000
        username = ""
        password = ""
      }
      etcd3 { 
        serverAddr = "http://localhost:2379"
      }
      file { 
        name = "file.conf"
      }
    }

### ☞ 实体类 ###

/** * Created with IntelliJ IDEA. * * @author Demo_Null * @date 2020/12/3 * @description 订单实体类 */
    @Data
    public class Order implements Serializable { 
    
        private static final long SerialVersionUID = 1L;
    
        @Id
        @GeneratedValue(strategy= GenerationType.IDENTITY)
        private Long id;
    
        // 商品 id
        private Long productId;
    
        // 商品价格
        private Integer productPrice;
    
        // 商品数量
        private Integer productNum;
    
        // 是否付款
        private Boolean flag;
    }

### ☞ 持久层 ###

/** * Created with IntelliJ IDEA. * * @author Demo_Null * @date 2020/12/3 * @description */
    public interface OrderDao extends JpaRepository<Orders, Long>, JpaSpecificationExecutor<Orders> { 
    }

### ☞ service ###

/** * Created with IntelliJ IDEA. * * @author Demo_Null * @date 2020/12/3 * @description OrderService 接口 */
    public interface OrderService { 
        // 创建订单
        void create(Orders orders);
    }

/** * Created with IntelliJ IDEA. * * @author Demo_Null * @date 2020/12/3 * @description OrderService 实现类 */
    @Service
    @Slf4j
    public class OrderServiceImpl implements OrderService { 
    
        @Autowired
        private OrderDao orderDao;
    
        @Resource
        private AccountService accountService;
    
        @Resource
        private StorageService storageService;
    
        @Override
        public void create(Orders orders) { 
            log.info("###### 开始创建订单 ######");
            orders.setFlag(false);
            Orders save = orderDao.save(orders);
            log.info("###### 结束创建订单 ######");
    
            log.info("###### 开始减库存 ######");
            storageService.deduct(save.getProductId(), save.getProductNum());
            log.info("###### 结束减库存 ######");
    
            log.info("###### 开始减余额 ######");
            accountService.debit(save.getUserId(), save.getProductPrice());
            log.info("###### 结束减余额 ######");
    
            log.info("###### 开始修改订单状态 ######");
            save.setFlag(true);
            orderDao.save(save);
            log.info("###### 结束修改订单状态 ######");
        }
    }

/** * Created with IntelliJ IDEA. * * @author Demo_Null * @date 2020/12/3 * @description account-server 远程调用 */ 
    @Component
    @FeignClient("account-server")
    public interface AccountService { 
        // 扣减余额
        @PostMapping("/account/debit")
        void debit(@RequestParam("userId") Long userId, @RequestParam("money") Integer money);
    }

/** * Created with IntelliJ IDEA. * * @author Demo_Null * @date 2020/12/3 * @description storage-server 远程调用 */
    @Component
    @FeignClient("storage-server")
    public interface StorageService { 
        // 扣减库存
        @PostMapping("/storage/deduct")
        void deduct(@RequestParam("id") Long id, @RequestParam("count") Integer count);
    }

### ☞ controller ###

/** * Created with IntelliJ IDEA. * * @author Demo_Null * @date 2020/12/3 * @description */
    @RestController
    @RequestMapping("/order")
    public class OrderController { 
        @Autowired
        private OrderService orderService;
    
        @GetMapping("/create")
        public String create(Orders orders) { 
            orderService.create(orders);
            return "创建成功";
        }
    }

### ☞ seata 代理数据源 ###

/** * Created with IntelliJ IDEA. * * @author gaohu9712@163.com * @date 2020/12/3 * @description */
    @Configuration
    public class DataSourceConfig { 
    
        @Bean
        @ConfigurationProperties(prefix = "spring.datasource")
        public DruidDataSource druidDataSource() { 
            return new DruidDataSource();
        }
    
        /** * 需要将 DataSourceProxy 设置为主数据源，否则事务无法回滚 * * @param druidDataSource The DruidDataSource * @return The default datasource */
        @Primary
        @Bean("dataSource")
        public DataSource dataSource(DruidDataSource druidDataSource) { 
            return new DataSourceProxy(druidDataSource);
        }
    
    	// 如果使用 MyBatis 还需要额外注入 org.apache.ibatis.session.SqlSessionFactory
        @Bean
        public SqlSessionFactory sqlSessionFactoryBean(DataSourceProxy dataSourceProxy) throws Exception { 
            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
            sqlSessionFactoryBean.setDataSource(dataSourceProxy);
            sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory());
            return sqlSessionFactoryBean.getObject();
        }
    }

### ☞ 项目结构 ###

博客中只构建 order 模块，另外两个模块构建方式类似，请自行构建或下载源码 [☞ GitHub][GitHub]  
![在这里插入图片描述][20201203144230876.png]

## 1.3 无分布式事务测试 ##

当订单创建成功后，准备扣减库存时发生错误，若此时没有分布式事务可能会造成订单创建了，库存没有减的问题，此类问题比比皆是。如不使用分布式事务简直就是一场灾难，当然你也可以只使用一个库。  
![在这里插入图片描述][2020120314574447.png]

## 1.4 使用分布式事务 ##

我们只需要使用一个 @GlobalTransactional 注解在业务方法上就可以实现分布式事务。  
![在这里插入图片描述][20201203172335201.png]

@Service
    @Slf4j
    public class OrderServiceImpl implements OrderService { 
    
        @Autowired
        private OrderDao orderDao;
    
        @Resource
        private AccountService accountService;
    
        @Resource
        private StorageService storageService;
    
        @Override
        @GlobalTransactional
        public void create(Orders orders) { 
            log.info("###### 开始创建订单 ######");
            orders.setFlag(false);
            Orders save = orderDao.save(orders);
            log.info("###### 结束创建订单 ######");
    
            log.info("###### 开始减库存 ######");
            storageService.deduct(save.getProductId(), save.getProductNum());
            log.info("###### 结束减库存 ######");
    
            log.info("###### 开始减余额 ######");
            accountService.debit(save.getUserId(), save.getProductPrice());
            log.info("###### 结束减余额 ######");
    
            log.info("###### 开始修改订单状态 ######");
            save.setFlag(true);
            orderDao.save(save);
            log.info("###### 结束修改订单状态 ######");
        }
    }

[Spring Cloud Alibaba _ Seata]: https://blog.csdn.net/Demo_Null/article/details/110467843
[20201203093203866.png_pic_center]: /images/20221120/f8b7c09c669d40dd882dbd9ad5d7fa74.png
[GitHub]: https://github.com/java-software/spring-cloud-alibaba-seata
[20201203144230876.png]: /images/20221120/48b106af7cd7413ca9cb5e80baa6aaf1.png
[2020120314574447.png]: /images/20221120/140b92b9a81a415d892d97a83c5f1caf.png
[20201203172335201.png]: /images/20221120/28a04f6ce39542fa953142056a83df6a.png