SpringCloud - Spring Cloud Alibaba 之 Seata分布式事务服务；TCC事务模式机制（二十三）

末蓝、 2023-09-28 19:17 284阅读 0赞

#### 阅读本文前可先参考： ####

[SpringCloud - Spring Cloud Alibaba 之 Seata分布式事务服务详解；部署（十八）\_MinggeQingchun的博客-CSDN博客][SpringCloud - Spring Cloud Alibaba _ Seata_MinggeQingchun_-CSDN]

[SpringCloud - Spring Cloud Alibaba 之 Seata分布式事务服务；AT事务模式（二十）\_MinggeQingchun的博客-CSDN博客][SpringCloud - Spring Cloud Alibaba _ Seata_AT_MinggeQingchun_-CSDN]

## Seata TCC 事务模式 ##

AT模式基本上能满足我们使用分布式事务大部分需求，但涉及非关系型数据库与中间件的操作、跨公司服务的调用、跨语言的应用调用就需要结合TCC模式

[http://seata.io/zh-cn/docs/dev/mode/tcc-mode.html][http_seata.io_zh-cn_docs_dev_mode_tcc-mode.html]

一个分布式的全局事务，整体是两阶段提交（Try \- \[Comfirm/Cancel\]）的模型

根据两阶段行为模式的不同，我们将分支事务划分为 **Automatic (Branch) Transaction Mode** 和 **TCC (Branch) Transaction Mode**

![0dce02f6655229d3f9f0ffc7aa705f50.png][]

AT 模式（[参考链接 TBD][http_seata.io_zh-cn_docs_dev_mode_tcc-mode.html]）基于 **支持本地 ACID 事务** 的 **关系型数据库**：

*  一阶段 prepare 行为：在本地事务中，一并提交业务数据更新和相应回滚日志记录
 *  二阶段 commit 行为：马上成功结束，**自动** 异步批量清理回滚日志
 *  二阶段 rollback 行为：通过回滚日志，**自动** 生成补偿操作，完成数据回滚

TCC 模式，不依赖于底层数据资源的事务支持（需要程序员编写代码实现提交和回滚）：

*  一阶段 prepare 行为：调用 **自定义** 的 prepare 逻辑
 *  二阶段 commit 行为：调用 **自定义** 的 commit 逻辑
 *  二阶段 rollback 行为：调用 **自定义** 的 rollback 逻辑

TCC 模式，是指支持把 **自定义** 的分支事务纳入到全局事务的管理中

通俗来说，Seata的TCC模式就是手工版本的AT模式，它允许你自定义两阶段的处理逻辑而不需要依赖AT模式的undo\_log回滚表

#### 1、创建数据库、表、插入数据等 ####

（1）accountdb账户库、account账户表

SET NAMES utf8mb4;
    SET FOREIGN_KEY_CHECKS = 0;
     
    -- ----------------------------
    -- Table structure for account
    -- ----------------------------
    DROP TABLE IF EXISTS `account`;
    CREATE TABLE `account`  (
      `id` int(20) NOT NULL AUTO_INCREMENT,
      `user_id` int(20) NULL DEFAULT NULL,
      `balance` decimal(20, 0) NULL DEFAULT NULL,
      `update_time` datetime(6) NULL DEFAULT NULL,
      PRIMARY KEY (`id`) USING BTREE
    ) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
     
    SET FOREIGN_KEY_CHECKS = 1;

（2）productdb产品库、product产品表

SET NAMES utf8mb4;
    SET FOREIGN_KEY_CHECKS = 0;
     
    -- ----------------------------
    -- Table structure for product
    -- ----------------------------
    DROP TABLE IF EXISTS `product`;
    CREATE TABLE `product`  (
      `id` int(20) NOT NULL AUTO_INCREMENT,
      `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
      `price` decimal(10, 2) NULL DEFAULT NULL,
      `stock` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
      `add_time` datetime(6) NULL DEFAULT NULL,
      `update_time` datetime(6) NULL DEFAULT NULL,
      PRIMARY KEY (`id`) USING BTREE
    ) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
     
    SET FOREIGN_KEY_CHECKS = 1;

（3）orderdb订单库、orders 订单表

SET NAMES utf8mb4;
    SET FOREIGN_KEY_CHECKS = 0;
     
    -- ----------------------------
    -- Table structure for orders
    -- ----------------------------
    DROP TABLE IF EXISTS `orders`;
    CREATE TABLE `orders`  (
      `id` int(20) NOT NULL AUTO_INCREMENT,
      `user_id` int(20) NULL DEFAULT NULL,
      `product_id` int(20) NULL DEFAULT NULL,
      `pay_amount` decimal(20, 0) NULL DEFAULT NULL,
      `add_time` datetime(6) NULL DEFAULT NULL,
      `update_time` datetime(6) NULL DEFAULT NULL,
      PRIMARY KEY (`id`) USING BTREE
    ) ENGINE = InnoDB AUTO_INCREMENT = 6 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
     
    SET FOREIGN_KEY_CHECKS = 1;

（4）undo\_log表

[Seata AT 模式][Seata AT]

-- 注意此处0.7.0+ 增加字段 context
    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,
      PRIMARY KEY (`id`),
      UNIQUE KEY `ux_undo_log` (`xid`,`branch_id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

注：

每个库必须创建 undo\_log 表，是 Seata AT模式必须创建的表，主要用于分支事务的回滚

![736430a464d3487eb7a6842a4c36d4a0.png][]

[Seata AT 模式][Seata AT]

![937693cb145e41e2bc5df395aa1ebd69.png][]

![1d9c991463d248e3ad3b07ca3afcccfd.png][]

## 一、SpringBoot单体应用多数据源TCC事务 ##

在Spring Boot单体项目中，使用了多数据源，就要保证多个数据源的数据一致性，即产生了分布式事务的问题，采用Seata的AT事务模式来解决该分布式事务问题

以下图购物下单为例

![050c3df109e54595bc5068490d297794.png][]

1、创建一个 springboot应用，命名 springcloud-alibaba-3-seata-tcc-transaction

2、添加依赖

<groupId>com.company</groupId>
        <artifactId>springcloud-alibaba-3-seata-tcc-transaction</artifactId>
        <version>1.0.0</version>
    
        <name>springcloud-alibaba-3-seata-tcc-transaction</name>
        <description>Demo project for Spring Boot</description>
    
        <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>2.3.12.RELEASE</spring-boot.version>
            <spring-cloud-alibaba.version>2.2.7.RELEASE</spring-cloud-alibaba.version>
        </properties>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
    
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </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>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                
            </dependency>
    
            
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.3</version>
            </dependency>
    
            
            <dependency>
                <groupId>io.seata</groupId>
                <artifactId>seata-spring-boot-starter</artifactId>
                <version>1.4.2</version>
            </dependency>
    
            
            <dependency>
                <groupId>com.baomidou</groupId>
                <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
                <version>3.2.0</version>
            </dependency>
    
            
            <dependency>
                <groupId>com.alibaba.nacos</groupId>
                <artifactId>nacos-client</artifactId>
                <version>2.1.0</version>
            </dependency>
        </dependencies>
    
        
        <dependencyManagement>
            <dependencies>
                <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>
                
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>Hoxton.SR12</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-dependencies</artifactId>
                    <version>${spring-boot.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <source>1.8</source>
                        <target>1.8</target>
                        <encoding>UTF-8</encoding>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
                
                <plugin>
                    <groupId>org.mybatis.generator</groupId>
                    <artifactId>mybatis-generator-maven-plugin</artifactId>
                    <version>1.4.0</version>
                    <configuration>
                        
                        <configurationFile>src/main/resources/generatorConfig.xml</configurationFile>
                        
                        <verbose>true</verbose>
                        
                        <overwrite>true</overwrite>
                    </configuration>
                </plugin>
            </plugins>
    
            <resources>
                <resource>
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.xml</include>
                    </includes>
                </resource>
                <resource>
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.*</include>
                    </includes>
                </resource>
                
                <resource>
                    <directory>src/main/webapp</directory>
                    <targetPath>META-INF/services</targetPath>
                    <includes>
                        <include>**/*.*</include>
                    </includes>
                </resource>
            </resources>
        </build>

3、 application.properties配置文件

#内嵌服务器端口
    server.port=8081
    
    #应用服务名称
    spring.application.name=springcloud-alibaba-3-seata-tcc-transaction
    
    # 设置默认的数据源或者数据源组，默认值即为master
    spring.datasource.dynamic.primary=order-ds
    
    # 订单order数据源配置
    spring.datasource.dynamic.datasource.order-ds.url=jdbc:mysql://192.168.133.129:3306/orderdb?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&rewriteBatchedStatements=true&useSSL=false
    spring.datasource.dynamic.datasource.order-ds.driver-class-name=com.mysql.cj.jdbc.Driver
    spring.datasource.dynamic.datasource.order-ds.username=root
    spring.datasource.dynamic.datasource.order-ds.password=123456
    
    # 商品product数据源配置
    spring.datasource.dynamic.datasource.product-ds.url=jdbc:mysql://192.168.133.129:3306/productdb?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&rewriteBatchedStatements=true&useSSL=false
    spring.datasource.dynamic.datasource.product-ds.driver-class-name=com.mysql.cj.jdbc.Driver
    spring.datasource.dynamic.datasource.product-ds.username=root
    spring.datasource.dynamic.datasource.product-ds.password=123456
    
    # 账户account数据源配置
    spring.datasource.dynamic.datasource.account-ds.url=jdbc:mysql://192.168.133.129:3306/accountdb?serverTimezone=GMT%2B8&useUnicode=true&characterEncoding=utf8&rewriteBatchedStatements=true&useSSL=false
    spring.datasource.dynamic.datasource.account-ds.driver-class-name=com.mysql.cj.jdbc.Driver
    spring.datasource.dynamic.datasource.account-ds.username=root
    spring.datasource.dynamic.datasource.account-ds.password=123456
    
    # 是否启动对Seata的集成
    spring.datasource.dynamic.seata=true
    
    
    #-----------------------------------------------------------
    #单机版 tc server 配置
    # Seata应用编号，默认为 ${spring.application.name}
    seata.application-id=springboot-tcc-seata
    # Seata事务组编号，用于TC集群名，一般格式为：${spring.application.name}-group
    seata.tx-service-group=springboot-tcc-seata-group
    # 虚拟组和分组的映射 seata.service.vgroup-mapping.${seata.tx-service-group}=default
    seata.service.vgroup-mapping.springboot-tcc-seata-group=default
    # 分组和Seata服务的映射，此处default指上面 seata.service.vgroup-mapping.springboot-seata-group 的值 default
    seata.service.grouplist.default=192.168.133.129:8091
    # 存储模式 默认 file模式
    seata.config.type=file
    # 默认为 file
    seata.registry.type=file
    #------------------------------------------------------------
    
    
    #------------------------------------------------------------
    ##集群版 tc server 配置
    ## Seata应用编号，默认为 ${spring.application.name}
    #seata.application-id=springboot-tcc-seata
    ## Seata事务组编号，用于TC集群名，一般格式为：${spring.application.name}-group
    #seata.tx-service-group=springboot-tcc-seata-group
    ## 虚拟组和分组的映射 seata.service.vgroup-mapping.${seata.tx-service-group}=default
    #seata.service.vgroup-mapping.springboot-tcc-seata-group=default
    #------------------------------------------------------------
    
    #设置使用注册中心
    #seata.registry.type=nacos
    #seata.registry.nacos.cluster=default
    #seata.registry.nacos.application=seata-server
    #seata.registry.nacos.group=SEATA_GROUP
    #seata.registry.nacos.server-addr=192.168.133.129:8848
    #
    #seata.enable-auto-data-source-proxy=false
    #seata.client.rm.lock.retry-policy-branch-rollback-on-conflict=false
    
    
    #配置 undo_log 的解析方式
    seata.client.undo.log-serialization=myJackson

4、编写相应的 controller、model、mapper、service类，这里只给出调用顺序相关的类

controller测试类

@Slf4j //lombok
    @RestController
    public class OrderController {
    
        @Autowired
        private OrderService orderService;
    
        @RequestMapping("/order")
        public Integer createOrder(@RequestParam("userId") Integer userId,
                                   @RequestParam("productId") Integer productId) throws Exception {
    
            log.info("请求下单, 用户:{}, 商品:{}", userId, productId);
    
            return orderService.createOrder(userId, productId);
        }
    }
    
    
    
    @Slf4j
    @Service
    public class OrderServiceImpl implements OrderService {
    
        @Autowired
        private OrdersMapper ordersMapper;
    
        @Autowired
        private AccountService accountService;
    
        @Autowired
        private ProductService productService;
    
        @Override
        @DS(value = "order-ds")
        @GlobalTransactional //seata全局事务注解， TM 事务发起方
        public Integer createOrder(Integer userId, Integer productId) throws Exception {
            Integer amount = 1; // 购买数量暂时设置为 1
    
            log.info("当前 XID: {}", RootContext.getXID());
    
            // 减库存
            Product product = productService.reduceStock(productId, amount);
    
            // 减余额
            accountService.reduceBalance(userId, product.getPrice());
    
            // 下订单
            Orders order = new Orders();
            order.setUserId(userId);
            order.setProductId(productId);
            order.setPayAmount(product.getPrice().multiply(new BigDecimal(amount)));
    
            ordersMapper.insertSelective(order);
    
            log.info("下订单: {}", order.getId());
    
            int a = 10 / 0;
    
            // 返回订单编号
            return order.getId();
        }
    }

AccountService

@LocalTCC
    public interface AccountService {
    
        /**
         * 扣除余额
         * 定义两阶段提交
         * name = reduceStock为一阶段try方法
         * commitMethod = commitTcc 为二阶段确认方法
         * rollbackMethod = cancel 为二阶段取消方法
         * BusinessActionContextParameter注解 可传递参数到二阶段方法
         *
         * @param userId 用户ID
         * @param money  扣减金额
         * @throws Exception 失败时抛出异常
         */
        @TwoPhaseBusinessAction(name = "reduceBalance", commitMethod = "commitTcc", rollbackMethod = "cancelTcc")
        void reduceBalance(@BusinessActionContextParameter(paramName = "userId") Integer userId,
                           @BusinessActionContextParameter(paramName = "money") BigDecimal money);
    
        /**
         * 确认方法、可以另命名，但要保证与commitMethod一致
         * context可以传递try方法的参数
         *
         * @param context 上下文
         * @return boolean
         */
        boolean commitTcc(BusinessActionContext context);
    
        /**
         * 二阶段取消方法
         *
         * @param context 上下文
         * @return boolean
         */
        boolean cancelTcc(BusinessActionContext context);
    
    }
    
    
    
    @Slf4j
    @Service
    public class AccountServiceImpl implements AccountService {
    
        @Autowired
        private AccountMapper accountMapper;
    
        @DS(value = "account-ds")
        @Override
        public void reduceBalance(Integer userId, BigDecimal money) {
            log.info("当前 XID: {}", RootContext.getXID());
    
            // 检查余额
            Account account = accountMapper.selectAccountByUserId(userId);
            if (account.getBalance().doubleValue() < money.doubleValue()) {
                throw new RuntimeException("余额不足");
            }
    
            // 扣除余额
            int updateCount = accountMapper.reduceBalance(userId, money);
            // 扣除成功
            if (updateCount == 0) {
                throw new RuntimeException("余额不足");
            }
            log.info("扣除用户 {} 余额成功", userId);
    
            //int a = 10 / 0;
        }
    
        /**
         * tcc服务（confirm）方法
         * 可以空确认
         *
         * @param context 上下文
         * @return boolean
         */
        @DS(value = "account-ds")
        @Override
        public boolean commitTcc(BusinessActionContext context) {
            log.info("Confirm阶段，AccountServiceImpl, commitTcc --> xid = {}", context.getXid() + ", commitTcc提交成功");
            return true;
        }
    
        /**
         * tcc服务（cancel）方法
         * 实现中间件、非关系型数据库的回滚操作
         * @param context 上下文
         * @return boolean
         */
        @DS(value = "account-ds")
        @Override
        public boolean cancelTcc(BusinessActionContext context) {
            log.info("Cancel阶段，AccountServiceImpl, cancelTcc --> xid = " + context.getXid() + ", cancelTcc提交失败");
            //可以实现中间件、非关系型数据库的回滚操作
            log.info("Cancel阶段，AccountServiceImpl, cancelTcc this data: userId= {}, money = {}", context.getActionContext("userId"), context.getActionContext("money"));
    
            //进行数据库回滚处理
            Integer userId = (Integer)context.getActionContext("userId");
            BigDecimal money = (BigDecimal)context.getActionContext("money");
    
            //把余额再加回去
            accountMapper.increaseBalance(userId, money);
    
            return true;
        }
    }

ProductService

@LocalTCC
    public interface ProductService {
    
        /**
         * 减库存
         *
         * 定义两阶段提交
         * name = reduceStock为一阶段try方法
         * commitMethod = commitTcc 为二阶段确认方法
         * rollbackMethod = cancel 为二阶段取消方法
         * BusinessActionContextParameter注解 可传递参数到二阶段方法
         *
         * @param productId 商品ID
         * @param amount    扣减数量
         * @throws Exception 扣减失败时抛出异常
         */
        @TwoPhaseBusinessAction(name = "reduceStock", commitMethod = "commitTcc", rollbackMethod = "cancelTcc")
        Product reduceStock(@BusinessActionContextParameter(paramName = "productId") Integer productId,
                            @BusinessActionContextParameter(paramName = "amount") Integer amount);
    
        /**
         * 二阶段提交方法
         *
         * 确认方法、可以另命名，但要保证与commitMethod一致
         * context可以传递try方法的参数
         *
         * @param context 上下文
         * @return boolean
         */
        boolean commitTcc(BusinessActionContext context);
    
        /**
         * 二阶段回滚方法
         *
         * @param context 上下文
         * @return boolean
         */
        boolean cancelTcc(BusinessActionContext context);
    
    }
    
    
    
    @Slf4j
    @Service
    public class ProductServiceImpl implements ProductService {
    
        @Autowired
        private AccountService accountService;
    
        @Autowired
        private ProductMapper productMapper;
    
        @DS(value = "product-ds")
        @Override
        public Product reduceStock(Integer productId, Integer amount) {
            log.info("当前 XID: {}", RootContext.getXID());
    
            // 检查库存
            Product product = productMapper.selectByPrimaryKey(productId);
            if (product.getStock() < amount) {
                throw new RuntimeException("库存不足");
            }
    
            // 扣减库存
            int updateCount = productMapper.reduceStock(productId, amount);
            // 扣除成功
            if (updateCount == 0) {
                throw new RuntimeException("库存不足");
            }
    
            // 扣除成功
            log.info("扣除 {} 库存成功", productId);
    
            return product;
        }
    
        /**
         * tcc服务（confirm）方法
         * 可以空确认
         *
         * @param context 上下文
         * @return boolean
         */
        @DS(value = "product-ds")
        @Override
        public boolean commitTcc(BusinessActionContext context) {
            log.info("Confirm阶段，ProductServiceImpl, commitTcc --> xid = " + context.getXid() + ", commitTcc提交成功");
            return true;
        }
    
        /**
         * tcc服务（cancel）方法
         *
         * @param context 上下文
         * @return boolean
         */
        @DS(value = "product-ds")
        @Override
        public boolean cancelTcc(BusinessActionContext context) {
            log.info("Cancel阶段，ProductServiceImpl, cancelTcc --> xid = " + context.getXid() + ", cancelTcc提交失败");
    
            //实现中间件、非关系型数据库的回滚操作
            log.info("Cancel阶段，ProductServiceImpl, cancelTcc this data: {}, {}", context.getActionContext("productId"), context.getActionContext("amount"));
    
            //进行数据库回滚处理
            Integer productId = (Integer)context.getActionContext("productId");
            Integer amount = (Integer)context.getActionContext("amount");
            //把库存再加回去 (避免数据出问题，加个锁，分布式环境下就需要分布式锁)
            productMapper.increaseStock(productId, amount);
    
            return true;
        }
    }

#### **@LocalTCC注解** ####

标识此TCC为本地模式，即该事务是本地调用，非RPC调用

@LocalTCC一定需要注解在接口上，此接口可以是寻常的业务接口，只要实现了TCC的两阶段提交对应方法即可

#### **@TwoPhaseBusinessAction注解** ####

标识为TCC模式，注解try方法，其中name为当前tcc方法的bean名称，写方法名便可（全局唯一），commitMethod指提交方法，rollbackMethod指事务回滚方法，指定好三个方法之后，Seata会根据事务的成功或失败，通过动态代理去帮我们自动调用提交或者回滚

#### **@BusinessActionContextParameter 注解** ####

将参数传递到二阶段（commitMethod/rollbackMethod）的方法

#### **BusinessActionContext** ####

指TCC事务上下文，携带了业务方法的参数

## 二、Spring Cloud Alibaba的TCC分布式事务 ##

![e297a3fa37e7443dbb48e12f47670dad.png][]

### 测试应用 ###

1、创建 4 个SpringBoot 模块

#### （1）springcloud-alibaba-3-seata-tcc-commons ####

<groupId>com.company</groupId>
        <artifactId>springcloud-alibaba-3-seata-tcc-commons</artifactId>
        <version>1.0.0</version>
    
        <dependencies>
            
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.16</version>
            </dependency>
    
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
                <version>3.0.0</version>
            </dependency>
    
        </dependencies>

@FeignClient(name = "springcloud-alibaba-3-seata-tcc-account")
    public interface FeignAccountService {
    
        /**
         * 扣除余额
         *
         * @param userId 用户ID
         * @param money  扣减金额
         * @throws Exception 失败时抛出异常
         */
        @PostMapping("/account/reduceBalance")
        void reduceBalance(@RequestParam("userId") Integer userId, @RequestParam("money") BigDecimal money);
    
    }
    
    
    @FeignClient(name = "springcloud-alibaba-3-seata-tcc-order")
    public interface FeignOrderService {
    
        /**
         * 创建订单
         *
         * @param userId 用户ID
         * @param productId 产品ID
         * @return 订单编号
         * @throws Exception 创建订单失败，抛出异常
         */
        Integer createOrder(Integer userId, Integer productId) throws Exception;
    
    }
    
    @FeignClient(name = "springcloud-alibaba-3-seata-tcc-product")
    public interface FeignProductService {
    
        /**
         * 减库存
         *
         * @param productId 商品ID
         * @param amount    扣减数量
         * @throws Exception 扣减失败时抛出异常
         */
        @PostMapping("/product/reduceStock")
        Product reduceStock(@RequestParam("productId") Integer productId, @RequestParam("amount") Integer amount);
    }

#### （2）springcloud-alibaba-3-seata-tcc-order ####

<groupId>com.company</groupId>
        <artifactId>springcloud-alibaba-3-seata-tcc-order</artifactId>
        <version>1.0.0</version>
    
        <name>springcloud-alibaba-3-seata-tcc-order</name>
        <description>Demo project for Spring Boot</description>
    
        <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>2.3.12.RELEASE</spring-boot.version>
            <spring-cloud-alibaba.version>2.2.7.RELEASE</spring-cloud-alibaba.version>
        </properties>
    
        <dependencies>
            <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>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>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.3</version>
            </dependency>
    
            
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
                <exclusions>
                    <exclusion>
                        <groupId>io.seata</groupId>
                        <artifactId>seata-spring-boot-starter</artifactId>
                    </exclusion>
                </exclusions>
            </dependency>
    
            
            <dependency>
                <groupId>io.seata</groupId>
                <artifactId>seata-spring-boot-starter</artifactId>
                <version>1.4.2</version>
            </dependency>
    
            
            <dependency>
                <groupId>com.company</groupId>
                <artifactId>springcloud-alibaba-3-seata-tcc-commons</artifactId>
                <version>1.0.0</version>
            </dependency>
    
        </dependencies>
    
        
        <dependencyManagement>
            <dependencies>
                <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>
                
                <dependency>
                    <groupId>org.springframework.cloud</groupId>
                    <artifactId>spring-cloud-dependencies</artifactId>
                    <version>Hoxton.SR12</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
                <dependency>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-dependencies</artifactId>
                    <version>${spring-boot.version}</version>
                    <type>pom</type>
                    <scope>import</scope>
                </dependency>
            </dependencies>
        </dependencyManagement>
    
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <version>3.8.1</version>
                    <configuration>
                        <source>1.8</source>
                        <target>1.8</target>
                        <encoding>UTF-8</encoding>
                    </configuration>
                </plugin>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
    
            <resources>
                <resource>
                    <directory>src/main/java</directory>
                    <includes>
                        <include>**/*.xml</include>
                    </includes>
                </resource>
                <resource>
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.*</include>
                    </includes>
                </resource>
            </resources>
        </build>

@Slf4j
    @RestController
    public class OrderController {
    
        @Autowired
        private OrderService orderService;
    
        /**
         * 下单操作，发起分布式事务
         *
         * @param userId
         * @param productId
         * @return
         * @throws Exception
         */
        @RequestMapping("/order")
        public Integer createOrder(@RequestParam("userId") Integer userId,
                                   @RequestParam("productId") Integer productId) throws Exception {
    
            log.info("[createOrder] 请求下单, 用户:{}, 商品:{}", userId, productId);
    
            return orderService.createOrder(userId, productId);
        }
    }
    
    
    @Slf4j
    @Service
    public class OrderServiceImpl implements OrderService {
    
        @Autowired
        private OrdersMapper ordersMapper;
    
        @Autowired
        private FeignProductService feignProductService;
    
        @Autowired
        private FeignAccountService feignAccountService;
    
        @Override
        @GlobalTransactional //seata全局事务注解， TM 分布式全局事务发起者
        public Integer createOrder(Integer userId, Integer productId) {
            Integer amount = 1; // 购买数量，暂时设为 1
    
            log.info("[createOrder] 当前 XID: {}", RootContext.getXID());
    
            // 减库存 （feign的调用） http远程调用
            Product product = feignProductService.reduceStock(productId, amount);
    
            // 减余额
            feignAccountService.reduceBalance(userId, product.getPrice());
    
            // 下订单
            Orders order = new Orders();
            order.setUserId(userId);
            order.setProductId(productId);
            order.setPayAmount(product.getPrice().multiply(new BigDecimal(amount)));
    
            ordersMapper.insertSelective(order);
    
            log.info("[createOrder] 下订单: {}", order.getId());
    
            int a = 10 / 0;
    
            // 返回订单编号
            return order.getId();
        }
    }

#### （3）springcloud-alibaba-3-seata-tcc-product ####

@LocalTCC
    public interface ProductService {
    
        /**
         * 减库存
         *
         * 定义两阶段提交
         * name = reduceStock为一阶段try方法
         * commitMethod = commitTcc 为二阶段确认方法
         * rollbackMethod = cancel 为二阶段取消方法
         * BusinessActionContextParameter注解 可传递参数到二阶段方法
         *
         * @param productId 商品ID
         * @param amount    扣减数量
         * @throws Exception 扣减失败时抛出异常
         */
        @TwoPhaseBusinessAction(name = "reduceStock", commitMethod = "commitTcc", rollbackMethod = "cancelTcc")
        Product reduceStock(@BusinessActionContextParameter(paramName = "productId") Integer productId,
                            @BusinessActionContextParameter(paramName = "amount") Integer amount);
    
        /**
         * 确认方法、可以另命名，但要保证与commitMethod一致
         * context可以传递try方法的参数
         *
         * @param context 上下文
         * @return boolean
         */
        boolean commitTcc(BusinessActionContext context);
    
        /**
         * 二阶段取消方法
         *
         * @param context 上下文
         * @return boolean
         */
        boolean cancelTcc(BusinessActionContext context);
    
    }
    
    
    @Slf4j
    @Service
    public class ProductServiceImpl implements ProductService {
    
        @Autowired
        private ProductMapper productMapper;
    
        /**
         * tcc服务（try）方法
         * 也是实际业务方法
         *
         * @param productId 商品ID
         * @param amount    扣减数量
         * @return
         */
        @Override
        public Product reduceStock(Integer productId, Integer amount) {
            log.info("[reduceStock] 当前 XID: {}", RootContext.getXID());
    
            // 检查库存
            Product product = productMapper.selectByPrimaryKey(productId);
            if (product.getStock() < amount) {
                throw new RuntimeException("库存不足");
            }
    
            // 减库存
            int updateCount = productMapper.reduceStock(productId, amount);
            // 减库存失败
            if (updateCount == 0) {
                throw new RuntimeException("库存不足");
            }
    
            // 减库存成功
            log.info("减库存 {} 库存成功", productId);
    
            return product;
        }
    
        /**
         * tcc服务（confirm）方法
         * 可以空确认
         *
         * @param context 上下文
         * @return boolean
         */
        @Override
        public boolean commitTcc(BusinessActionContext context) {
            log.info("Confirm阶段，ProductServiceImpl, commitTcc --> xid = " + context.getXid() + ", commitTcc提交成功");
            return true;
        }
    
        /**
         * tcc服务（cancel）方法
         *
         * @param context 上下文
         * @return boolean
         */
        @Override
        public boolean cancelTcc(BusinessActionContext context) {
            log.info("Cancel阶段，ProductServiceImpl, cancelTcc --> xid = " + context.getXid() + ", cancelTcc提交失败");
            //TODO 这里可以实现中间件、非关系型数据库的回滚操作
            log.info("Cancel阶段，ProductServiceImpl, cancelTcc this data: {}, {}", context.getActionContext("productId"), context.getActionContext("amount"));
    
            //进行数据库回滚处理
            Integer productId = (Integer)context.getActionContext("productId");
            Integer amount = (Integer)context.getActionContext("amount");
    
            //把库存再加回去
            productMapper.increaseStock(productId, amount);
    
            return true;
        }
    }

#### （4）springcloud-alibaba-3-seata-tcc-account ####

@LocalTCC
    public interface AccountService {
    
        /**
         * 扣除余额
         * 定义两阶段提交
         * name = reduceStock为一阶段try方法
         * commitMethod = commitTcc 为二阶段确认方法
         * rollbackMethod = cancel 为二阶段取消方法
         * BusinessActionContextParameter注解 可传递参数到二阶段方法
         *
         * @param userId 用户ID
         * @param money  扣减金额
         * @throws Exception 失败时抛出异常
         */
        @TwoPhaseBusinessAction(name = "reduceBalance", commitMethod = "commitTcc", rollbackMethod = "cancelTcc")
        void reduceBalance(@BusinessActionContextParameter(paramName = "userId") Integer userId,
                           @BusinessActionContextParameter(paramName = "money") BigDecimal money);
    
        /**
         * 确认方法、可以另命名，但要保证与commitMethod一致
         * context可以传递try方法的参数
         *
         * @param context 上下文
         * @return boolean
         */
        boolean commitTcc(BusinessActionContext context);
    
        /**
         * 二阶段取消方法
         *
         * @param context 上下文
         * @return boolean
         */
        boolean cancelTcc(BusinessActionContext context);
    }
    
    
    @Slf4j
    @Service
    public class AccountServiceImpl implements AccountService {
    
        @Autowired
        private AccountMapper accountMapper;
    
        @Override
        public void reduceBalance(Integer userId, BigDecimal money) {
            log.info("[reduceBalance] 当前 XID: {}", RootContext.getXID());
    
            // 检查余额
            Account account = accountMapper.selectAccountByUserId(userId);
            if (account.getBalance().doubleValue() < money.doubleValue()) {
                throw new RuntimeException("余额不足");
            }
    
            // 扣除余额
            int updateCount = accountMapper.reduceBalance(userId, money);
            // 扣除成功
            if (updateCount == 0) {
                throw new RuntimeException("余额不足");
            }
            log.info("[reduceBalance] 扣除用户 {} 余额成功", userId);
        }
    
        /**
         * tcc服务（confirm）方法
         * 可以空确认
         *
         * @param context 上下文
         * @return boolean
         */
        @Override
        public boolean commitTcc(BusinessActionContext context) {
            log.info("Confirm阶段，AccountServiceImpl, commitTcc --> xid = {}", context.getXid() + ", commitTcc提交成功");
            return true;
        }
    
        /**
         * tcc服务（cancel）方法
         *
         * @param context 上下文
         * @return boolean
         */
        @Override
        public boolean cancelTcc(BusinessActionContext context) {
            log.info("Cancel阶段，AccountServiceImpl, cancelTcc --> xid = " + context.getXid() + ", cancelTcc提交失败");
            //TODO 这里可以实现中间件、非关系型数据库的回滚操作
            log.info("Cancel阶段，AccountServiceImpl, cancelTcc this data: userId= {}, money = {}", context.getActionContext("userId"), context.getActionContext("money"));
    
            //进行数据库回滚处理
            Integer userId = (Integer)context.getActionContext("userId");
            BigDecimal money = (BigDecimal)context.getActionContext("money");
    
            //幂等性问题
    
            //把余额再加回去
            accountMapper.increaseBalance(userId, money);
    
            return true;
        }
    }

[SpringCloud - Spring Cloud Alibaba _ Seata_MinggeQingchun_-CSDN]: https://blog.csdn.net/MinggeQingchun/article/details/126100300
[SpringCloud - Spring Cloud Alibaba _ Seata_AT_MinggeQingchun_-CSDN]: https://blog.csdn.net/MinggeQingchun/article/details/126153368
[http_seata.io_zh-cn_docs_dev_mode_tcc-mode.html]: http://seata.io/zh-cn/docs/dev/mode/tcc-mode.html
[0dce02f6655229d3f9f0ffc7aa705f50.png]: https://img-blog.csdnimg.cn/img_convert/0dce02f6655229d3f9f0ffc7aa705f50.png
[Seata AT]: http://seata.io/zh-cn/docs/dev/mode/at-mode.html
[736430a464d3487eb7a6842a4c36d4a0.png]: https://img-blog.csdnimg.cn/736430a464d3487eb7a6842a4c36d4a0.png
[937693cb145e41e2bc5df395aa1ebd69.png]: https://img-blog.csdnimg.cn/937693cb145e41e2bc5df395aa1ebd69.png
[1d9c991463d248e3ad3b07ca3afcccfd.png]: https://img-blog.csdnimg.cn/1d9c991463d248e3ad3b07ca3afcccfd.png
[050c3df109e54595bc5068490d297794.png]: https://img-blog.csdnimg.cn/050c3df109e54595bc5068490d297794.png
[e297a3fa37e7443dbb48e12f47670dad.png]: https://img-blog.csdnimg.cn/e297a3fa37e7443dbb48e12f47670dad.png