一、前言

通过以下系列章节：

docker-compose 实现Seata Server高可用部署 | Spring Cloud 51

Seata AT 模式理论学习、事务隔离及部分源码解析 | Spring Cloud 52

Spring Boot集成Seata利用AT模式分布式事务示例 | Spring Cloud 53

Seata XA 模式理论学习、使用及注意事项 | Spring Cloud54

Seata TCC 模式理论学习、生产级使用示例搭建及注意事项 | Spring Cloud55

Seata TCC 模式下解决幂等、悬挂、空回滚问题 | Spring Cloud56

Seata Saga 模式理论学习、生产级使用示例搭建及注意事项（一） | Spring Cloud57

我们对Seata及其AT、XA、TCC、Saga事务模式的理论、使用有了深入的了解，今天专注学习Seata的Saga事务模式代码实现；并区别与官网，我们利用openfeign进行生产级示例搭建，降低入门难度。

二、示例搭建

书接上回，本示例是一个商品下单的案例，一共有三个服务和一个公共模块：

• order-saga：业务服务，用户下单操作将在这里完成。
• account-saga：账户服务，可以查询/修改用户的账户信息
• storage-saga：仓储服务，可以查询/修改商品的库存数量。
• common-tcc：公共模块，包含：实体类、openfeign接口、统一异常处理等。

2.1 业务表结构

2.1.1 订单表

DROP TABLE IF EXISTS `t_order`;
CREATE TABLE `t_order`  (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `user_id` varchar(255) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL,
  `commodity_code` varchar(255) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL,
  `count` int NULL DEFAULT 0,
  `money` decimal(10, 2) NULL DEFAULT 0.00,
  `business_key` varchar(255) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 23 CHARACTER SET = utf8mb3 COLLATE = utf8mb3_general_ci ROW_FORMAT = Dynamic;

2.1.2 库存表

-- ----------------------------
-- Table structure for t_storage
-- ----------------------------
DROP TABLE IF EXISTS `t_storage`;
CREATE TABLE `t_storage`  (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `commodity_code` varchar(255) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL,
  `count` int NULL DEFAULT 0,
  `business_key` varchar(255) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE INDEX `commodity_code`(`commodity_code` ASC) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8mb3 COLLATE = utf8mb3_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_storage
-- ----------------------------
INSERT INTO `t_storage` VALUES (1, 'iphone', 3, '');

2.1.3 账户表

-- ----------------------------
-- Table structure for t_account
-- ----------------------------
DROP TABLE IF EXISTS `t_account`;
CREATE TABLE `t_account`  (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `user_id` varchar(255) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL COMMENT '用户ID',
  `money` decimal(10, 2) NULL DEFAULT 0.00 COMMENT '账户余额',
  `business_key` varchar(255) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci NULL DEFAULT NULL COMMENT '业务标识',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 2 CHARACTER SET = utf8mb3 COLLATE = utf8mb3_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_account
-- ----------------------------
INSERT INTO `t_account` VALUES (1, 'user1', 500.00, '');

2.2 项目总体结构

2.3 common-saga 搭建

2.3.1 实体类

com/gm/seata/openfeign/entity/Account.java：

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
import java.math.BigDecimal;

@Data
@TableName("t_account")
public class Account {

    @TableId(type = IdType.ASSIGN_ID)
    private long id;

    private String userId;

    private BigDecimal money;

    private String businessKey;
}

com/gm/seata/openfeign/entity/Order.java：

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
import java.math.BigDecimal;

@Data
@TableName("t_order")
public class Order {

    @TableId(type = IdType.ASSIGN_ID)
    private long id;

    private String userId;

    private String commodityCode;

    private int count;

    private BigDecimal money;

    private String businessKey;
}

com/gm/seata/openfeign/entity/Storage.java：

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName("t_storage")
public class Storage {

    @TableId(type = IdType.ASSIGN_ID)
    private long id;

    private String commodityCode;

    private int count;

    private String businessKey;
}

2.3.2 feign接口

com/gm/seata/openfeign/feign/AccountServiceApi.java：

import com.gm.seata.openfeign.util.R;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import java.math.BigDecimal;

@FeignClient(value = "account-saga")
public interface AccountServiceApi {

    /**
     * 扣除账户余额
     *
     * @param userId
     * @param money
     * @return
     */
    @RequestMapping(value = "deduct", method = RequestMethod.GET)
    R<Boolean> deduct(@RequestParam("businessKey") String businessKey, @RequestParam("userId") String userId, @RequestParam("money") BigDecimal money);

    /**
     * 补偿扣除的账户余额
     *
     * @param userId
     * @param money
     * @return
     */
    @RequestMapping(value = "compensateDeduct", method = RequestMethod.GET)
    R<Boolean> compensateDeduct(@RequestParam("businessKey") String businessKey, @RequestParam("userId") String userId, @RequestParam("money") BigDecimal money);
}

com/gm/seata/openfeign/feign/StorageServiceApi.java：

import com.gm.seata.openfeign.util.R;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;

@FeignClient(value = "storage-saga")
public interface StorageServiceApi {

    /**
     * 扣除库存
     *
     * @param commodityCode
     * @param count
     * @return
     */
    @RequestMapping(value = "deduct", method = RequestMethod.GET)
    R<Boolean> deduct(@RequestParam("businessKey") String businessKey, @RequestParam("commodityCode") String commodityCode, @RequestParam("count") Integer count);

    /**
     * 补偿扣除的库存
     *
     * @param commodityCode
     * @param count
     * @return
     */
    @RequestMapping(value = "compensateDeduct", method = RequestMethod.GET)
    R<Boolean> compensateDeduct(@RequestParam("businessKey") String businessKey, @RequestParam("commodityCode") String commodityCode, @RequestParam("count") Integer count);
}

2.3.3 feign 微服务调用异码处理

com/gm/seata/openfeign/handle/FeignErrorDecoder.java：

import com.alibaba.fastjson.JSONObject;
import com.gm.seata.openfeign.util.ErrorEnum;
import feign.Response;
import feign.RetryableException;
import feign.Util;
import feign.codec.ErrorDecoder;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Configuration;
import java.nio.charset.Charset;

@Slf4j
@Configuration
public class FeignErrorDecoder extends ErrorDecoder.Default {

    @Override
    public Exception decode(String methodKey, Response response) {
        try {
            // 可以自定义一些逻辑
            String message = Util.toString(response.body().asReader(Charset.forName("utf8")));
            JSONObject jsonObject = JSONObject.parseObject(message);
            int code = jsonObject.getInteger("code");
            ErrorEnum errorEnum = ErrorEnum.getEnumByCode(code);
            // 包装成自己自定义的异常
            return new RuntimeException(String.valueOf(errorEnum.getCode()));
        } catch (Exception e) {
            log.error("非已知异常", e.getMessage(), e);
        }

        Exception exception = super.decode(methodKey, response);
        // 如果是RetryableException，则返回继续重试
        if (exception instanceof RetryableException) {
            return exception;
        }
        return new RuntimeException(String.valueOf(ErrorEnum.UNKNOWN_EXCEPTION.getCode()));
    }
}

2.3.4 Controller 统一异常处理

com/gm/seata/openfeign/handle/GlobalBizExceptionHandler.java：

import com.gm.seata.openfeign.util.ErrorEnum;
import com.gm.seata.openfeign.util.R;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.annotation.Order;
import org.springframework.http.HttpStatus;;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;

/**
 * 全局异常处理器
 */
@Slf4j
@Order(10000)
@RestControllerAdvice
public class GlobalBizExceptionHandler {

    /**
     * 全局异常.
     *
     * @param e the e
     * @return R
     */
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    public R handleGlobalException(Exception e) {
        log.error("全局异常信息 ex={}", e.getMessage(), e);
        R r = null;
        // 根据异常信息与已知异常进行匹配
        try {
            int code = Integer.parseInt(e.getLocalizedMessage());
            ErrorEnum errorEnum = ErrorEnum.getEnumByCode(code);
            if (errorEnum != null) {
                r = R.restResult(null, errorEnum.getCode(), errorEnum.getTitle());
            }
        } finally {
            if (e instanceof feign.FeignException) {
                ErrorEnum errorEnum = ErrorEnum.UNKNOWN_EXCEPTION;
                r = R.restResult(null, errorEnum.getCode(), errorEnum.getTitle());
            }
            if (r == null) {
                r = R.failed(e.getLocalizedMessage());
            }
        }
        return r;
    }
}

3.2.4 Controller 统一异常处理

com/gm/seata/openfeign/handle/GlobalBizExceptionHandler.java：

import com.gm.seata.openfeign.util.ErrorEnum;
import com.gm.seata.openfeign.util.R;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.annotation.Order;
import org.springframework.http.HttpStatus;;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;

/**
 * 全局异常处理器
 */
@Slf4j
@Order(10000)
@RestControllerAdvice
public class GlobalBizExceptionHandler {

    /**
     * 全局异常.
     *
     * @param e the e
     * @return R
     */
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    public R handleGlobalException(Exception e) {
        log.error("全局异常信息 ex={}", e.getMessage(), e);
        R r = null;
        // 根据异常信息与已知异常进行匹配
        try {
            int code = Integer.parseInt(e.getLocalizedMessage());
            ErrorEnum errorEnum = ErrorEnum.getEnumByCode(code);
            if (errorEnum != null) {
                r = R.restResult(null, errorEnum.getCode(), errorEnum.getTitle());
            }
        } finally {
            if (e instanceof feign.FeignException) {
                ErrorEnum errorEnum = ErrorEnum.UNKNOWN_EXCEPTION;
                r = R.restResult(null, errorEnum.getCode(), errorEnum.getTitle());
            }
            if (r == null) {
                r = R.failed(e.getLocalizedMessage());
            }
        }
        return r;
    }
}

3.2.5 已知异常枚举类

com/gm/seata/openfeign/util/ErrorEnum.java：

import lombok.AllArgsConstructor;
import lombok.Getter;

@Getter
@AllArgsConstructor
public enum ErrorEnum {

    NO_SUCH_COMMODITY(3000, "无此商品"),
    STORAGE_LOW_PREPARE(3001, "库存不足，预扣库存失败"),
    STORAGE_LOW_COMMIT(3002, "库存不足，扣库存失败"),
    NO_SUCH_ACCOUNT(4000, "无此账户"),
    ACCOUNT_LOW_PREPARE(4001, "余额不足，预扣款失败"),
    ACCOUNT_LOW_COMMIT(4002, "余额不足，扣款失败"),
    UNKNOWN_EXCEPTION(9999, "远程方法调用异常");

    private final Integer code;
    private final String title;

    public static ErrorEnum getEnumByCode(int code) {
        for (ErrorEnum error : ErrorEnum.values()) {
            if (error.getCode().equals(code)) {
                return error;
            }
        }
        return null;
    }
}

3.2.6 响应信息结构体

com/gm/seata/openfeign/util/R.java：

import lombok.*;
import lombok.experimental.Accessors;
import java.io.Serializable;

/**
 * 响应信息主体
 *
 */
@ToString
@NoArgsConstructor
@AllArgsConstructor
@Accessors(chain = true)
public class R<T> implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * 成功标记
     */
    private static final Integer SUCCESS = 0;

    /**
     * 失败标记
     */
    private static final Integer FAIL = 1;

    @Getter
    @Setter
    private int code;

    @Getter
    @Setter
    private String msg;

    @Getter
    @Setter
    private T data;

    public static <T> R<T> ok() {
        return restResult(null, SUCCESS, null);
    }

    public static <T> R<T> ok(T data) {
        return restResult(data, SUCCESS, null);
    }

    public static <T> R<T> ok(T data, String msg) {
        return restResult(data, SUCCESS, msg);
    }

    public static <T> R<T> failed() {
        return restResult(null, FAIL, null);
    }

    public static <T> R<T> failed(String msg) {
        return restResult(null, FAIL, msg);
    }

    public static <T> R<T> failed(T data) {
        return restResult(data, FAIL, null);
    }

    public static <T> R<T> failed(T data, String msg) {
        return restResult(data, FAIL, msg);
    }

    public static <T> R<T> restResult(T data, int code, String msg) {
        R<T> apiResult = new R<>();
        apiResult.setCode(code);
        apiResult.setData(data);
        apiResult.setMsg(msg);
        return apiResult;
    }
}

3.2.7 自动配置实现

在src/main/resources/META-INF/spring路径下新建文件org.springframework.boot.autoconfigure.AutoConfiguration.imports内容如下：

com.gm.seata.openfeign.handle.GlobalBizExceptionHandler
com.gm.seata.openfeign.handle.FeignErrorDecoder

新建文件org.springframework.cloud.openfeign.FeignClient.imports内容如下：

com.gm.seata.openfeign.feign.AccountServiceApi
com.gm.seata.openfeign.feign.OrderServiceApi
com.gm.seata.openfeign.feign.StorageServiceApi

通过上述方式实现自动配置。

2.4 account-saga 搭建

2.4.1 完整依赖

seata/openfeign-saga/account-saga/pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>openfeign-saga</artifactId>
        <groupId>com.gm</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>account-saga</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.gm</groupId>
            <artifactId>common-saga</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</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>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.3.1</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2.4.2 配置文件

src/main/resources/bootstrap.yml：

server:
  port: 3011

spring:
  application:
    name: @artifactId@
  cloud:
    nacos:
      username: @nacos.username@
      password: @nacos.password@
      discovery:
        server-addr: ${NACOS_HOST:nacos1.kc}:${NACOS_PORT:8848}
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://192.168.0.35:3306/seata-saga-demo?useUnicode=true&characterEncoding=UTF-8&rewriteBatchedStatements=true&allowMultiQueries=true&serverTimezone=Asia/Shanghai
    username: root
    password: '1qaz@WSX'

# mybatis-plus配置控制台打印完整带参数SQL语句
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

2.5.3 功能搭建

2.4.3.1 启动类

com/gm/seata/openfeign/AccountTCCApplication.java：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class AccountTCCApplication {

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

2.4.3.2 Mapper类

com/gm/seata/openfeign/mapper/AccountMapper.java：

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.gm.seata.openfeign.entity.Account;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

@Mapper
public interface AccountMapper extends BaseMapper<Account> {

    @Select("SELECT * FROM t_account WHERE user_id = #{userId} limit 1")
    Account getAccountByUserId(@Param("userId") String userId);
}

2.4.3.3 Service类

com/gm/seata/openfeign/service/AccountService.java：

import java.math.BigDecimal;

public interface AccountService {

    /**
     * 扣除账户余额
     *
     * @param userId
     * @param money
     * @return
     */
    boolean deduct(String businessKey, String userId, BigDecimal money);

    /**
     * 补充扣除的账户余额
     *
     * @param userId
     * @param money
     * @return
     */
    boolean compensateDeduct(String businessKey, String userId, BigDecimal money);
}

com/gm/seata/openfeign/service/impl/AccountServiceImpl.java：

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.gm.seata.openfeign.entity.Account;
import com.gm.seata.openfeign.mapper.AccountMapper;
import com.gm.seata.openfeign.service.AccountService;
import com.gm.seata.openfeign.util.ErrorEnum;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.math.BigDecimal;

@Slf4j
@Service
public class AccountServiceImpl implements AccountService {

    @Autowired
    AccountMapper accountMapper;

    @Override
    public boolean deduct(String businessKey, String userId, BigDecimal money) {
        Account account = accountMapper.getAccountByUserId(userId);
        if (account == null) {
            //throw new RuntimeException("账户不存在");
            throw new RuntimeException(String.valueOf(ErrorEnum.NO_SUCH_ACCOUNT.getCode()));
        }
        // 账户余额 与 本次消费金额进行 比较
        if (account.getMoney().compareTo(money) < 0) {
            //throw new RuntimeException("余额不足，预扣款失败");
            throw new RuntimeException(String.valueOf(ErrorEnum.ACCOUNT_LOW_PREPARE.getCode()));
        }
        account.setMoney(account.getMoney().subtract(money));
        account.setBusinessKey(businessKey);

        QueryWrapper query = new QueryWrapper();
        query.eq("user_id", userId);
        int i = accountMapper.update(account, query);
        log.info("{} 账户余额扣除 {} 元", userId, money);
        return i == 1;
    }

    @Override
    public boolean compensateDeduct(String businessKey, String userId, BigDecimal money) {
        Account account = accountMapper.getAccountByUserId(userId);

        account.setMoney(account.getMoney().add(money));

        QueryWrapper query = new QueryWrapper();
        query.eq("user_id", userId);
        query.eq("business_key", businessKey);
        int i = accountMapper.update(account, query);
        if (i == 1) {
            log.info("{} 账户补偿余额 {} 元", userId, money);
        } else {
            log.info("{} 账户无需补偿", userId);
        }
        return i == 1;
    }
}

2.4.3.4 Controller类

com/gm/seata/openfeign/controller/AccountController.java：

import com.gm.seata.openfeign.service.AccountService;
import com.gm.seata.openfeign.util.R;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import java.math.BigDecimal;

@RestController
public class AccountController {

    @Autowired
    AccountService accountService;

    /**
     * 扣除账户余额
     *
     * @param userId
     * @param money
     * @return
     */
    @RequestMapping(value = "deduct", method = RequestMethod.GET)
    public R<Boolean> deduct(@RequestParam("businessKey") String businessKey, @RequestParam("userId") String userId, @RequestParam("money") BigDecimal money) {
        return R.ok(accountService.deduct(businessKey, userId, money));
    }

    /**
     * 补偿扣除的账户余额
     *
     * @param userId
     * @param money
     * @return
     */
    @RequestMapping(value = "compensateDeduct", method = RequestMethod.GET)
    public R<Boolean> compensateDeduct(@RequestParam("businessKey") String businessKey, @RequestParam("userId") String userId, @RequestParam("money") BigDecimal money) {
        return R.ok(accountService.compensateDeduct(businessKey, userId, money));
    }
}

对外提供两个方法，对应Saga 状态机中：ServiceTask节点AccountService-deduct远程调用和补偿节点Compensation节点AccountService-compensateDeduc远程调用，如下图：

2.5 storage-saga 搭建

2.5.1 完整依赖

减少重复内容，请参考 2.4.1 部分，自动修改

2.5.2 配置文件

减少重复内容，请参考 2.4.2 部分，自动修改

2.5.3 功能搭建

2.5.3.1 启动类

com/gm/seata/openfeign/StorageTCCApplication.java：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication
@EnableDiscoveryClient
public class StorageTCCApplication {

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

2.5.3.2 Mapper类

com/gm/seata/openfeign/mapper/StorageMapper.java：

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.gm.seata.openfeign.entity.Storage;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

@Mapper
public interface StorageMapper extends BaseMapper<Storage> {

    @Select("SELECT * FROM t_storage WHERE commodity_code = #{commodityCode} limit 1")
    Storage getStorageByCommodityCode(@Param("commodityCode") String commodityCode);
}

2.5.3.3 Service类

com/gm/seata/openfeign/service/StorageService.java：

public interface StorageService {

    /**
     * 扣除库存
     *
     * @param commodityCode
     * @param count
     * @return
     */
    boolean deduct(String businessKey, String commodityCode, Integer count);

    /**
     * 补充扣除库存
     *
     * @param commodityCode
     * @param count
     * @return
     */
    boolean compensateDeduct(String businessKey, String commodityCode, Integer count);
}

com/gm/seata/openfeign/service/impl/StorageServiceImpl.java：

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.gm.seata.openfeign.entity.Storage;
import com.gm.seata.openfeign.mapper.StorageMapper;
import com.gm.seata.openfeign.service.StorageService;
import com.gm.seata.openfeign.util.ErrorEnum;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Slf4j
@Service
public class StorageServiceImpl implements StorageService {

    @Autowired
    StorageMapper storageMapper;

    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean deduct(String businessKey, String commodityCode, Integer count) {
        Storage storage = storageMapper.getStorageByCommodityCode(commodityCode);
        if (storage == null) {
            //throw new RuntimeException("商品不存在");
            throw new RuntimeException(String.valueOf(ErrorEnum.NO_SUCH_COMMODITY.getCode()));
        }
        if (storage.getCount() < count) {
            //throw new RuntimeException("库存不足，预扣库存失败");
            throw new RuntimeException(String.valueOf(ErrorEnum.STORAGE_LOW_PREPARE.getCode()));
        }
        storage.setCount(storage.getCount() - count);
        storage.setBusinessKey(businessKey);

        QueryWrapper query = new QueryWrapper();
        query.eq("commodity_code", commodityCode);
        Integer i = storageMapper.update(storage, query);
        log.info("{} 商品库存扣除 {} 个", commodityCode, count);
        return i == 1;
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public boolean compensateDeduct(String businessKey, String commodityCode, Integer count) {
        Storage storage = storageMapper.getStorageByCommodityCode(commodityCode);
        storage.setCount(storage.getCount() + count);

        QueryWrapper query = new QueryWrapper();
        query.eq("commodity_code", commodityCode);
        query.eq("business_key", businessKey);
        Integer i = storageMapper.update(storage, query);
        log.info("{} 商品补偿库存 {} 个", commodityCode, count);
        return i == 1;
    }
}

2.5.3.4 Controller类

com/gm/seata/openfeign/controller/StorageController.java：

import com.gm.seata.openfeign.service.StorageService;
import com.gm.seata.openfeign.util.R;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class StorageController {

    @Autowired
    StorageService storageService;

    /**
     * 扣除商品库存
     *
     * @param commodityCode
     * @param count
     * @return
     */
    @RequestMapping(value = "deduct", method = RequestMethod.GET)
    public R<Boolean> deduct(@RequestParam("businessKey") String businessKey, @RequestParam("commodityCode") String commodityCode, @RequestParam("count") Integer count) {
        return R.ok(storageService.deduct(businessKey, commodityCode, count));
    }

    /**
     * 扣除商品库存
     *
     * @param commodityCode
     * @param count
     * @return
     */
    @RequestMapping(value = "compensateDeduct", method = RequestMethod.GET)
    public R<Boolean> compensateDeduct(@RequestParam("businessKey") String businessKey, @RequestParam("commodityCode") String commodityCode, @RequestParam("count") Integer count) {
        return R.ok(storageService.compensateDeduct(businessKey, commodityCode, count));
    }
}

对外提供两个方法，对应Saga 状态机中：ServiceTask节点StorageService-deduct远程调用和补偿节点Compensation节点`StorageService-compensateDeduct远程调用，如下图：

2.6 order-saga 搭建

2.6.1 完整依赖

seata/openfeign-saga/common-saga/pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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">
    <parent>
        <artifactId>openfeign-saga</artifactId>
        <groupId>com.gm</groupId>
        <version>0.0.1-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>order-saga</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.gm</groupId>
            <artifactId>common-saga</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</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>
        </dependency>
        <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>


        <!-- 注意一定要引入对版本，要引入spring-cloud版本seata，而不是springboot版本的seata-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
            <!-- 排除掉springcloud默认的seata版本，以免版本不一致出现问题-->
            <exclusions>
                <exclusion>
                    <groupId>io.seata</groupId>
                    <artifactId>seata-spring-boot-starter</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>io.seata</groupId>
                    <artifactId>seata-all</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!-- 上面排除掉了springcloud默认色seata版本，此处引入和seata-server版本对应的seata包-->
        <dependency>
            <groupId>io.seata</groupId>
            <artifactId>seata-spring-boot-starter</artifactId>
            <version>1.6.1</version>
        </dependency>

        <!--<dependency>
            <groupId>io.seata</groupId>
            <artifactId>seata-spring-boot-starter</artifactId>
        </dependency>-->
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.3.1</version>
        </dependency>
        <dependency>
            <groupId>com.gm</groupId>
            <artifactId>common-tcc</artifactId>
            <version>0.0.1-SNAPSHOT</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>io.fabric8</groupId>
                <artifactId>docker-maven-plugin</artifactId>
            </plugin>
        </plugins>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
                <excludes>
                    <exclude>**/*.xlsx</exclude>
                    <exclude>**/*.xls</exclude>
                </excludes>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>false</filtering>
                <includes>
                    <include>**/*.xlsx</include>
                    <include>**/*.xls</include>
                </includes>
            </resource>
        </resources>
    </build>
</project>

2.6.2 配置文件

src/main/resources/bootstrap.yml：

server:
  port: 3012

spring:
  application:
    name: @artifactId@
  cloud:
    nacos:
      username: @nacos.username@
      password: @nacos.password@
      discovery:
        server-addr: ${NACOS_HOST:nacos1.kc}:${NACOS_PORT:8848}
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://192.168.0.35:3306/seata-saga-demo?useUnicode=true&characterEncoding=UTF-8&rewriteBatchedStatements=true&allowMultiQueries=true&serverTimezone=Asia/Shanghai
    username: root
    password: '1qaz@WSX'
seata:
  # 是否开启spring-boot自动装配，seata-spring-boot-starter 专有配置，默认true
  enabled: true
  # 是否开启数据源自动代理，seata-spring-boot-starter专有配置，默认会开启数据源自动代理，可通过该配置项关闭
  enable-auto-data-source-proxy: false
  # 配置自定义事务组名称，需与下方server.vgroupMapping配置一致，程序会通过用户配置的配置中心去寻找service.vgroupMapping
  tx-service-group: mygroup
  config: # 从nacos配置中心获取client端配置
    type: nacos
    nacos:
      server-addr: ${NACOS_HOST:nacos1.kc}:${NACOS_PORT:8848}
      group : DEFAULT_GROUP
      namespace: a4c150aa-fd09-4595-9afe-c87084b22105
      dataId: seataServer.properties
      username: @nacos.username@
      password: @nacos.username@
  registry: # 通过服务中心通过服务发现获取seata-server服务地址
    type: nacos
    nacos:
      # 注：客户端注册中心配置的serverAddr和namespace与Server端一致，clusterName与Server端cluster一致
      application: seata-server # 此处与seata-server的application一致，才能通过服务发现获取服务地址
      group : DEFAULT_GROUP
      server-addr: ${NACOS_HOST:nacos1.kc}:${NACOS_PORT:8848}
      userName: @nacos.username@
      password: @nacos.username@
      namespace: a4c150aa-fd09-4595-9afe-c87084b22105
  service:
    # 应用程序（客户端）会通过用户配置的配置中心去寻找service.vgroupMapping.[事务分组配置项]
    vgroup-mapping:
      # 事务分组配置项[mygroup]对应的值为TC集群名[default]，与Seata-Server中的seata.registry.nacos.cluster配置一致
      mygroup : default
    # 全局事务开关，默认false。false为开启，true为关闭
    disable-global-transaction: false
  client:
    rm:
      report-success-enable: true
management:
  endpoints:
    web:
      exposure:
        include: '*'

logging:
  level:
    io.seata: info

# mybatis-plus配置控制台打印完整带参数SQL语句
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

状态机文件src/main/resources/statelang/order.json：

{
  "nodes": [
    {
      "type": "node",
      "size": "80*72",
      "shape": "flow-rhombus",
      "color": "#13C2C2",
      "label": "AccountService-deduct-Choice",
      "stateId": "AccountService-deduct-Choice",
      "stateType": "Choice",
      "x": 467.875,
      "y": 286.5,
      "id": "c11238b3",
      "stateProps": {
        "Type": "Choice",
        "Choices": [
          {
            "Expression": "[deductResult] == true",
            "Next": "StorageService-deduct"
          }
        ],
        "Default": "Fail"
      },
      "index": 6
    },
    {
      "type": "node",
      "size": "39*39",
      "shape": "flow-circle",
      "color": "red",
      "label": "BService-save-catch",
      "stateId": "BService-save-catch",
      "stateType": "Catch",
      "x": 524.875,
      "y": 431.5,
      "id": "053ac3ac",
      "index": 7
    },
    {
      "type": "node",
      "size": "72*72",
      "shape": "flow-circle",
      "color": "#FA8C16",
      "label": "Start",
      "stateId": "Start",
      "stateType": "Start",
      "stateProps": {
        "StateMachine": {
          "Name": "order",
          "Comment": "经典的分布式调用",
          "Version": "0.0.1"
        },
        "Next": "AService"
      },
      "x": 467.875,
      "y": 53,
      "id": "973bd79e",
      "index": 11
    },
    {
      "type": "node",
      "size": "110*48",
      "shape": "flow-rect",
      "color": "#1890FF",
      "label": "AccountService-deduct",
      "stateId": "AccountService-deduct",
      "stateType": "ServiceTask",
      "stateProps": {
        "Type": "ServiceTask",
        "ServiceName": "accountService",
        "Next": "AccountService-deduct-Choice",
        "ServiceMethod": "deduct",
        "Input": [
          "$.[businessKey]",
          "$.[userId]",
          "$.[commodityCode]",
          "$.[count]"
        ],
        "Output": {
          "deductResult": "$.#root"
        },
        "Status": {
          "#root == true": "SU",
          "#root == false": "FA",
          "$Exception{java.lang.Throwable}": "UN"
        },
        "CompensateState": "AccountService-compensateDeduct",
        "Retry": []
      },
      "x": 467.875,
      "y": 172,
      "id": "e17372e4",
      "index": 12
    },
    {
      "type": "node",
      "size": "110*48",
      "shape": "flow-rect",
      "color": "#1890FF",
      "label": "StorageService-deduct",
      "stateId": "StorageService-deduct",
      "stateType": "ServiceTask",
      "stateProps": {
        "Type": "ServiceTask",
        "ServiceName": "storageService",
        "ServiceMethod": "deduct",
        "CompensateState": "StorageService- compensateDeduct",
        "Input": [
          "$.[businessKey]",
          "$.[userId]",
          "$.[commodityCode]",
          "$.[count]"
        ],
        "Output": {
          "deductResult": "$.#root"
        },
        "Status": {
          "#root == true": "SU",
          "#root == false": "FA",
          "$Exception{java.lang.Throwable}": "UN"
        },
        "Next": "StorageService-deduct-Choice"
      },
      "x": 467.125,
      "y": 411,
      "id": "a6c40952",
      "index": 13
    },
    {
      "type": "node",
      "size": "110*48",
      "shape": "flow-capsule",
      "color": "#722ED1",
      "label": "AccountService-compensateDeduct",
      "stateId": "AccountService-compensateDeduct",
      "stateType": "Compensation",
      "stateProps": {
        "Type": "Compensation",
        "ServiceName": "accountService",
        "ServiceMethod": "compensateDeduct",
        "Input": [
          "$.[businessKey]",
          "$.[userId]",
          "$.[commodityCode]",
          "$.[count]"
        ]
      },
      "x": 260.625,
      "y": 172.5,
      "id": "3b348652",
      "index": 14
    },
    {
      "type": "node",
      "size": "110*48",
      "shape": "flow-capsule",
      "color": "#722ED1",
      "label": "StorageService-compensateDeduct",
      "stateId": "StorageService-compensateDeduct",
      "stateType": "Compensation",
      "stateProps": {
        "Type": "Compensation",
        "ServiceName": "storageService",
        "ServiceMethod": "compensateDeduct",
        "Input": [
          "$.[businessKey]",
          "$.[userId]",
          "$.[commodityCode]",
          "$.[count]"
        ]
      },
      "x": 262.125,
      "y": 411,
      "id": "13b600b1",
      "index": 15
    },
    {
      "type": "node",
      "size": "72*72",
      "shape": "flow-circle",
      "color": "#05A465",
      "label": "Succeed",
      "stateId": "Succeed",
      "stateType": "Succeed",
      "x": 466.625,
      "y": 795,
      "id": "690e5c5e",
      "stateProps": {
        "Type": "Succeed"
      },
      "index": 16
    },
    {
      "type": "node",
      "size": "110*48",
      "shape": "flow-capsule",
      "color": "red",
      "label": "Compensation\nTrigger",
      "stateId": "CompensationTrigger",
      "stateType": "CompensationTrigger",
      "x": 881.625,
      "y": 430.5,
      "id": "757e057f",
      "stateProps": {
        "Type": "CompensationTrigger",
        "Next": "Fail"
      },
      "index": 17
    },
    {
      "type": "node",
      "size": "72*72",
      "shape": "flow-circle",
      "color": "red",
      "label": "Fail",
      "stateId": "Fail",
      "stateType": "Fail",
      "stateProps": {
        "Type": "Fail",
        "ErrorCode": "FAILED",
        "Message": "buy failed"
      },
      "x": 881.125,
      "y": 285.5,
      "id": "0131fc0c",
      "index": 18
    },
    {
      "type": "node",
      "size": "39*39",
      "shape": "flow-circle",
      "color": "red",
      "label": "AccountService-deduct-catch",
      "stateId": "AccountService-deduct-catch",
      "stateType": "Catch",
      "x": 518.125,
      "y": 183,
      "id": "0955401d"
    },
    {
      "type": "node",
      "size": "80*72",
      "shape": "flow-rhombus",
      "color": "#13C2C2",
      "label": "StorageService-deduct-Choice",
      "stateId": "StorageService-deduct-Choice",
      "stateType": "Choice",
      "x": 466.875,
      "y": 545.5,
      "id": "27978f5d",
      "stateProps": {
        "Type": "Choice",
        "Choices": [
          {
            "Expression": "[deductResult] == true",
            "Next": "OrderService-createOrder"
          }
        ],
        "Default": "Fail"
      }
    },
    {
      "type": "node",
      "size": "110*48",
      "shape": "flow-rect",
      "color": "#1890FF",
      "label": "OrderService-createOrder",
      "stateId": "OrderService-createOrder",
      "stateType": "ServiceTask",
      "stateProps": {
        "Type": "ServiceTask",
        "ServiceName": "orderService",
        "ServiceMethod": "createOrder",
        "CompensateState": "OrderService- compensateOrder",
        "Input": [
          "$.[businessKey]",
          "$.[userId]",
          "$.[commodityCode]",
          "$.[count]"
        ],
        "Output": {
          "createOrderResult": "$.#root"
        },
        "Status": {
          "#root == true": "SU",
          "#root == false": "FA",
          "$Exception{java.lang.Throwable}": "UN"
        },
        "Next": "Succeed"
      },
      "x": 466.625,
      "y": 676,
      "id": "9351460d"
    },
    {
      "type": "node",
      "size": "110*48",
      "shape": "flow-capsule",
      "color": "#722ED1",
      "label": "OrderService-compensateOrder",
      "stateId": "OrderService-compensateOrder",
      "stateType": "Compensation",
      "stateProps": {
        "Type": "Compensation",
        "ServiceName": "orderService",
        "ServiceMethod": "compensateOrder",
        "Input": [
          "$.[businessKey]",
          "$.[userId]",
          "$.[commodityCode]",
          "$.[count]"
        ]
      },
      "x": 261.625,
      "y": 675.5,
      "id": "b2789952"
    },
    {
      "type": "node",
      "size": "39*39",
      "shape": "flow-circle",
      "color": "red",
      "label": "OrderService-createOrder-catch",
      "stateId": "OrderService-createOrder-catch",
      "stateType": "Catch",
      "x": 523.125,
      "y": 696,
      "id": "466cf242"
    }
  ],
  "edges": [
    {
      "source": "973bd79e",
      "sourceAnchor": 2,
      "target": "e17372e4",
      "targetAnchor": 0,
      "id": "f0a9008f",
      "index": 0
    },
    {
      "source": "e17372e4",
      "sourceAnchor": 2,
      "target": "c11238b3",
      "targetAnchor": 0,
      "id": "cd8c3104",
      "index": 2,
      "label": "执行结果",
      "shape": "flow-smooth"
    },
    {
      "source": "c11238b3",
      "sourceAnchor": 2,
      "target": "a6c40952",
      "targetAnchor": 0,
      "id": "e47e49bc",
      "stateProps": {},
      "label": "执行成功",
      "shape": "flow-smooth",
      "index": 3
    },
    {
      "source": "c11238b3",
      "sourceAnchor": 1,
      "target": "0131fc0c",
      "targetAnchor": 3,
      "id": "e3f9e775",
      "stateProps": {},
      "label": "执行失败",
      "shape": "flow-smooth",
      "index": 4
    },
    {
      "source": "053ac3ac",
      "sourceAnchor": 1,
      "target": "757e057f",
      "targetAnchor": 3,
      "id": "3f7fe6ad",
      "stateProps": {
        "Exceptions": [
          "java.lang.Throwable"
        ],
        "Next": "CompensationTrigger"
      },
      "label": "StorageService-deduct异常触发补偿",
      "shape": "flow-smooth",
      "index": 5
    },
    {
      "source": "e17372e4",
      "sourceAnchor": 3,
      "target": "3b348652",
      "targetAnchor": 1,
      "id": "52a2256e",
      "style": {
        "lineDash": "4"
      },
      "index": 8,
      "label": "",
      "shape": "flow-smooth"
    },
    {
      "source": "a6c40952",
      "sourceAnchor": 3,
      "target": "13b600b1",
      "targetAnchor": 1,
      "id": "474512d9",
      "style": {
        "lineDash": "4"
      },
      "index": 9
    },
    {
      "source": "757e057f",
      "sourceAnchor": 0,
      "target": "0131fc0c",
      "targetAnchor": 2,
      "id": "1abf48fa",
      "index": 10
    },
    {
      "source": "0955401d",
      "sourceAnchor": 1,
      "target": "757e057f",
      "targetAnchor": 1,
      "id": "654280aa",
      "shape": "flow-polyline-round",
      "stateProps": {
        "Exceptions": [
          "java.lang.Throwable"
        ],
        "Next": "CompensationTrigger"
      },
      "label": "AccountService-deduct异常触发补偿"
    },
    {
      "source": "a6c40952",
      "sourceAnchor": 2,
      "target": "27978f5d",
      "targetAnchor": 0,
      "id": "f25a12eb",
      "shape": "flow-polyline-round",
      "label": "执行结果"
    },
    {
      "source": "27978f5d",
      "sourceAnchor": 2,
      "target": "9351460d",
      "targetAnchor": 0,
      "id": "99d78285",
      "shape": "flow-smooth",
      "stateProps": {},
      "label": "执行成功"
    },
    {
      "source": "9351460d",
      "sourceAnchor": 2,
      "target": "690e5c5e",
      "targetAnchor": 0,
      "id": "82670a92",
      "shape": "flow-polyline-round"
    },
    {
      "source": "9351460d",
      "sourceAnchor": 3,
      "target": "b2789952",
      "targetAnchor": 1,
      "id": "5db6a545",
      "shape": "flow-polyline-round",
      "style": {
        "lineDash": "4",
        "endArrow": false
      },
      "type": "Compensation"
    },
    {
      "source": "466cf242",
      "sourceAnchor": 1,
      "target": "757e057f",
      "targetAnchor": 2,
      "id": "a9f55df2",
      "shape": "flow-polyline-round",
      "stateProps": {
        "Exceptions": [
          "java.lang.Throwable"
        ],
        "Next": "CompensationTrigger"
      },
      "label": "OrderService-createOrder异常触发补偿"
    },
    {
      "source": "27978f5d",
      "sourceAnchor": 1,
      "target": "0131fc0c",
      "targetAnchor": 1,
      "id": "c303cae6",
      "shape": "flow-polyline-round",
      "stateProps": {},
      "label": "执行失败"
    }
  ]
}

2.6.3 功能搭建

2.6.3.1 启动类

com/gm/seata/openfeign/OrderSagaApplication.java：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients("com.gm.seata.openfeign.feign")
public class OrderSagaApplication {

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

2.6.3.2 状态机配置类

com/gm/seata/openfeign/config/StateMachineEngineConfig.java：

import io.seata.saga.engine.config.DbStateMachineConfig;
import io.seata.saga.engine.impl.ProcessCtrlStateMachineEngine;
import io.seata.saga.rm.StateMachineEngineHolder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import javax.sql.DataSource;
import java.util.concurrent.ThreadPoolExecutor;

/**
 * @Description 状态机配置
 */
@Configuration
public class StateMachineEngineConfig {

    @Autowired
    DataSource dataSource;

    @Bean
    public DbStateMachineConfig dbStateMachineConfig() {
        DbStateMachineConfig stateMachineConfig = new DbStateMachineConfig();
        stateMachineConfig.setDataSource(dataSource);
        stateMachineConfig.setResources(new String[]{"statelang/*.json"});
        stateMachineConfig.setEnableAsync(true);
        stateMachineConfig.setThreadPoolExecutor(threadExecutor());
        stateMachineConfig.setApplicationId("seata-server");
        stateMachineConfig.setTxServiceGroup("mygroup");
        return stateMachineConfig;
    }

    @Bean
    public ProcessCtrlStateMachineEngine stateMachineEngine() {
        ProcessCtrlStateMachineEngine processCtrlStateMachineEngine = new ProcessCtrlStateMachineEngine();
        processCtrlStateMachineEngine.setStateMachineConfig(dbStateMachineConfig());
        return processCtrlStateMachineEngine;
    }


    @Bean
    public StateMachineEngineHolder stateMachineEngineHolder() {
        StateMachineEngineHolder engineHolder = new StateMachineEngineHolder();
        engineHolder.setStateMachineEngine(stateMachineEngine());
        return engineHolder;
    }


    @Bean
    public ThreadPoolExecutor threadExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        //配置核心线程数
        executor.setCorePoolSize(1);
        //配置最大线程数
        executor.setMaxPoolSize(20);
        //配置队列大小
        executor.setQueueCapacity(99999);
        //配置线程池中的线程的名称前缀
        executor.setThreadNamePrefix("SAGA_ASYNC_EXE_");

        // 设置拒绝策略：当pool已经达到max size的时候，如何处理新任务
        // CALLER_RUNS：不在新线程中执行任务，而是有调用者所在的线程来执行
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        //执行初始化
        executor.initialize();
        return executor.getThreadPoolExecutor();
    }
}

2.6.3.3 Mapper类

com/gm/seata/openfeign/mapper/OrderMapper.java：

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.gm.seata.openfeign.entity.Order;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface OrderMapper extends BaseMapper<Order> {

}

2.6.3.4 Service类

com/gm/seata/openfeign/service/AccountService.java：

public interface AccountService {

    /**
     * 扣除账户余额
     *
     * @param businessKey
     * @param userId
     * @param commodityCode
     * @param count
     * @return
     */
    boolean deduct(String businessKey, String userId, String commodityCode, Integer count);

    /**
     * 补偿账户余额
     *
     * @param businessKey
     * @param userId
     * @param commodityCode
     * @param count
     * @return
     */
    boolean compensateDeduct(String businessKey, String userId, String commodityCode, Integer count);
}

com/gm/seata/openfeign/service/OrderService.java：

public interface OrderService {

    /**
     * 创建订单
     *
     * @param businessKey
     * @param userId
     * @param commodityCode
     * @param count
     * @return
     */
    boolean createOrder(String businessKey, String userId, String commodityCode, Integer count);

    /**
     * 补偿（移除）已创建订单
     *
     * @param businessKey
     * @param userId
     * @param commodityCode
     * @param count
     * @return
     */
    boolean compensateOrder(String businessKey, String userId, String commodityCode, Integer count);
}

com/gm/seata/openfeign/service/StorageService.java：

public interface StorageService {

    /**
     * 扣除库存
     *
     * @param businessKey
     * @param userId
     * @param commodityCode
     * @param count
     * @return
     */
    boolean deduct(String businessKey, String userId, String commodityCode, Integer count);

    /**
     * 补充扣除库存
     *
     * @param businessKey
     * @param userId
     * @param commodityCode
     * @param count
     * @return
     */
    boolean compensateDeduct(String businessKey, String userId, String commodityCode, Integer count);
}

com/gm/seata/openfeign/service/impl/AccountServiceImpl.java：

import com.gm.seata.openfeign.feign.AccountServiceApi;
import com.gm.seata.openfeign.service.AccountService;
import com.gm.seata.openfeign.util.R;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.math.BigDecimal;

@Slf4j
@Service(value = "accountService")
public class AccountServiceImpl implements AccountService {

    @Autowired
    AccountServiceApi accountServiceApi;


    @Override
    public boolean deduct(String businessKey, String userId, String commodityCode, Integer count) {
        log.info("saga状态机调用AccountService的deduct方法，参数businessKey={},userId={},commodityCode={},count={}", businessKey, userId, commodityCode, count);
        try {
            R<Boolean> result = accountServiceApi.deduct(businessKey, userId, new BigDecimal(count * 100.0));
            return result.getData();
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
    }

    @Override
    public boolean compensateDeduct(String businessKey, String userId, String commodityCode, Integer count) {
        log.info("saga状态机调用AccountService的compensateDeduct方法，参数businessKey={},userId={},commodityCode={},count={}", businessKey, userId, commodityCode, count);
        try {
            R<Boolean> result = accountServiceApi.compensateDeduct(businessKey, userId, new BigDecimal(count * 100.0));
            return result.getData();
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
    }
}

注意：通过@Service(value = "accountService")设置服务的beanId，定义正常业务及补偿业务发起远程服务调用

com/gm/seata/openfeign/service/impl/OrderServiceImpl.java：

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.gm.seata.openfeign.entity.Order;
import com.gm.seata.openfeign.mapper.OrderMapper;
import com.gm.seata.openfeign.service.OrderService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.math.BigDecimal;

@Slf4j
@Service(value = "orderService")
public class OrderServiceImpl implements OrderService {

    @Autowired
    OrderMapper orderMapper;

    @Override
    public boolean createOrder(String businessKey, String userId, String commodityCode, Integer count) {
        log.info("saga状态机调用OrderService的createOrder方法，参数businessKey={},userId={},commodityCode={},count={}", businessKey, userId, commodityCode, count);

        Order order = new Order();
        order.setCount(count);
        order.setCommodityCode(commodityCode);
        order.setUserId(userId);
        order.setMoney(new BigDecimal(count * 100.0));
        int i = orderMapper.insert(order);

        log.info("{} 用户购买的 {} 商品共计 {} 件，订单创建成功", userId, commodityCode, count);
        return i == 1;
    }

    @Override
    public boolean compensateOrder(String businessKey, String userId, String commodityCode, Integer count) {
        log.info("saga状态机调用OrderService的compensateOrder方法，参数businessKey={},userId={},commodityCode={},count={}", businessKey, userId, commodityCode, count);

        QueryWrapper query = new QueryWrapper();
        query.eq("commodity_code", commodityCode);
        query.eq("userId", commodityCode);
        query.eq("Money", new BigDecimal(count * 100.0));
        int i = orderMapper.delete(query);

        log.info("{} 用户购买的 {} 商品共计 {} 件，订单补充（移除）成功", userId, commodityCode, count);
        return i == 1;
    }
}

com/gm/seata/openfeign/service/impl/StorageServiceImpl.java：

import com.gm.seata.openfeign.feign.StorageServiceApi;
import com.gm.seata.openfeign.service.StorageService;
import com.gm.seata.openfeign.util.R;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Slf4j
@Service(value = "storageService")
public class StorageServiceImpl implements StorageService {

    @Autowired
    StorageServiceApi storageService;

    @Override
    public boolean deduct(String businessKey, String userId, String commodityCode, Integer count) {
        log.info("saga状态机调用StorageService的deduct方法，参数businessKey={},userId={},commodityCode={},count={}", businessKey, userId, commodityCode, count);
        try {
            R<Boolean> result = storageService.deduct(businessKey, commodityCode, count);
            return result.getData();
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
    }

    @Override
    public boolean compensateDeduct(String businessKey, String userId, String commodityCode, Integer count) {
        log.info("saga状态机调用StorageService的compensateDeduct方法，参数businessKey={},userId={},commodityCode={},count={}", businessKey, userId, commodityCode, count);
        try {
            R<Boolean> result = storageService.compensateDeduct(businessKey, commodityCode, count);
            return result.getData();
        } catch (Exception e) {
            throw new RuntimeException(e.getMessage());
        }
    }
}

2.6.3.5 Controller类

com/gm/seata/openfeign/controller/OrderController.java：

import com.gm.seata.openfeign.util.ErrorEnum;
import com.gm.seata.openfeign.util.R;
import io.seata.saga.engine.StateMachineEngine;
import io.seata.saga.statelang.domain.ExecutionStatus;
import io.seata.saga.statelang.domain.StateMachineInstance;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;
import java.util.Map;

@Slf4j
@RestController
public class OrderController {

    @Autowired
    StateMachineEngine stateMachineEngine;

    /**
     * 商品下单购买
     *
     * @param userId
     * @param commodityCode
     * @param count
     * @return
     */
    @RequestMapping(value = "buy", method = RequestMethod.GET)
    public R<String> buy(@RequestParam("userId") String userId, @RequestParam("commodityCode") String commodityCode, @RequestParam("count") Integer count) {
        //唯一健
        String businessKey = String.valueOf(System.currentTimeMillis());
        Map<String, Object> startParams = new HashMap<>();
        startParams.put("businessKey", businessKey);
        startParams.put("userId", userId);
        startParams.put("commodityCode", commodityCode);
        startParams.put("count", count);

        //同步执行
        StateMachineInstance inst = stateMachineEngine.startWithBusinessKey("order", null, businessKey, startParams);

        if (ExecutionStatus.SU.equals(inst.getStatus())) {
            log.info("成功,saga transaction execute Succeed. XID: {},Status: {},CompensationStatus: {}", inst.getId(), inst.getStatus(), inst.getCompensationStatus());
            return R.ok("下单成功");
        } else {
            log.info("成功,saga transaction execute Succeed. XID: {},Status: {},CompensationStatus: {}", inst.getId(), inst.getStatus(), inst.getCompensationStatus());
            try {
                int code = Integer.parseInt(inst.getException().getMessage());
                return R.restResult("下单失败", code, ErrorEnum.getEnumByCode(code).getTitle());
            } catch (Exception e) {
                return R.failed("下单失败", inst.getException().getMessage());
            }
        }
    }
}

注意：通过stateMachineEngine.startWithBusinessKey("order", null, businessKey, startParams);开启状态机

更多状态机API请见官网：http://seata.io/zh-cn/docs/user/saga.html

三、示例测试

3.1 正常下单

由2.1章节可知：账户余额500，库存3，每件商品单价100元。

请求地址：http://127.0.0.1:3012/buy?userId=user1&count=2&commodityCode=iphone

每请求一次，扣除余额200元，扣除库存2个，已知可正常下单1次

order-saga系统日志：

http请求返回：

数据库记录：

3.1 余额或库存下单失败

storage-saga系统日志：

order-saga系统日志：

全局事务回滚成功

数据库记录：