Spring Cloud集成分布式事务框架Seata 1.5.2（三）-阿里云开发者社区

package com.example.awesomebusiness.api;
import com.example.accountapi.api.WalletApi;
import org.springframework.cloud.openfeign.FeignClient;
/**
 * account：注册的服务名称；
 * contextId：注册到spring中的Bean名称，保证唯一性
 * path：对应服务端的requestMapping里面的value值，没有的话，可不写
 *
 * @author zouwei
 * @className AccountApiClient
 * @date: 2022/9/18 14:42
 * @description:
 */
@FeignClient(name = "account", contextId = "walletApi", path = "/wallet")
public interface WalletApiClient extends WalletApi {
}
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package com.example.awesomebusiness.api;
import com.example.orderapi.api.OrderApi;
import org.springframework.cloud.openfeign.FeignClient;
/**
 * @author zouwei
 * @className OrderApiClient
 * @date: 2022/9/27 23:24
 * @description:
 */
@FeignClient(name = "order", contextId = "orderApi", path = "/order")
public interface OrderApiClient extends OrderApi {
}
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接下来看看awesome-account的业务逻辑：

package com.example.awesomeaccount.service.impl;
import com.example.awesomeaccount.dao.mapper.WalletEnhanceMapper;
import com.example.awesomeaccount.service.IWalletService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
/**
 * @author zouwei
 * @className WalletServiceImpl
 * @date: 2022/9/27 21:20
 * @description:
 */
@Service
public class WalletServiceImpl implements IWalletService {
  @Resource
  private WalletEnhanceMapper walletEnhanceMapper;
  @Transactional
  @Override
  public Boolean deductMoney(String userId, long amount) {
    // 判断修改后的影响行数是否大于0
    // 对应sql：update wallet_tbl set money = money - #{amount,jdbcType=INTEGER} where user_id = #{userId,jdbcType=VARCHAR} and money <![CDATA[ >= ]]>#{amount,jdbcType=INTEGER}
    // WalletEnhanceMapper属于自定义的sql mapper，没有写在WalletMapper中，是因为避免重新生成Mapper的时候，自定义sql被覆盖
    return walletEnhanceMapper.deductMoney(userId, amount) > 0;
  }
}
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对应的controller如下：

package com.example.awesomeaccount.controller;
import com.example.accountapi.api.WalletApi;
import com.example.accountapi.model.AmountInfo;
import com.example.awesomeaccount.service.IWalletService;
import io.seata.core.context.RootContext;
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.RestController;
/**
 * WalletApi接口在account-api模块中
 *
 * @author zouwei
 * @className WalletController
 * @date: 2022/9/18 14:58
 * @description:
 */
@Slf4j
@RestController
@RequestMapping("/wallet")
public class WalletController implements WalletApi {
  @Autowired
  private IWalletService walletService;
  @Override
  public Boolean deductMoney(AmountInfo amountInfo) {
    String userId = amountInfo.getUserId();
    long amount = amountInfo.getAmount();
    // 打印分布式事务XID
    log.warn("XID:{}", RootContext.getXID());
    // 扣款
    return walletService.deductMoney(userId, amount);
  }
}
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package com.example.accountapi.api;
import com.example.accountapi.model.AmountInfo;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
/**
 * 供生产者和消费者共同使用
 *
 * @author zouwei
 * @className AccountApi
 * @date: 2022/9/18 14:31
 * @description:
 */
public interface WalletApi {
  /**
   * 扣钱
   *
   * @param amountInfo
   * @return
   */
  @PostMapping("/deductMoney")
  Boolean deductMoney(@RequestBody AmountInfo amountInfo);
}
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awesome-order与awesome-storage服务也是类似的代码结构：

package com.example.awesomeorder.service.impl;
import com.example.awesomeorder.api.StockApiClient;
import com.example.awesomeorder.dao.entity.Order;
import com.example.awesomeorder.dao.mapper.OrderMapper;
import com.example.awesomeorder.service.IOrderService;
import com.example.storageapi.model.OrderInfo;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
import java.time.LocalDateTime;
/**
 * @author zouwei
 * @className OrderServiceImpl
 * @date: 2022/9/27 22:47
 * @description:
 */
@Service
public class OrderServiceImpl implements IOrderService {
  @Resource
  private OrderMapper orderMapper;
  @Resource
  private StockApiClient stockApiClient;
  /**
   * 创建订单
   *
   * @param userId
   * @param commodityCode
   * @param count
   * @param unitPrice
   * @return
   */
  @Transactional
  @Override
  public Boolean createOrder(String userId, String commodityCode, int count, long unitPrice) {
    // 构建待扣减的库存信息
    OrderInfo orderInfo = new OrderInfo();
    // 设置商品编码
    orderInfo.setCommodityCode(commodityCode);
    // 设置需要扣减的数量
    orderInfo.setCount(count);
    // 先构建库存
    if (stockApiClient.deductStock(orderInfo)) {
      // 扣减库存成功后，准备创建订单
      Order order = new Order();
      // 创建时间
      order.setCreateTime(LocalDateTime.now());
      // 用户ID
      order.setUserId(userId);
      // 数量
      order.setCount(count);
      // 商品编码
      order.setCommodityCode(commodityCode);
      // 单价
      order.setUnitPrice(unitPrice);
      // 创建订单
      return orderMapper.insert(order) > 0;
    }
    // 扣减库存失败，订单创建失败
    return Boolean.FALSE;
  }
}
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package com.example.awesomeorder.api;
import com.example.storageapi.api.StockApi;
import org.springframework.cloud.openfeign.FeignClient;
/**
 * @author zouwei
 * @className StockApiClient
 * @date: 2022/9/28 00:34
 * @description:
 */
@FeignClient(name = "storage", contextId = "stockApi", path = "/stock")
public interface StockApiClient extends StockApi {
}
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package com.example.awesomeorder.controller;
import com.example.awesomeorder.service.IOrderService;
import com.example.orderapi.api.OrderApi;
import com.example.orderapi.model.OrderInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
 * @author zouwei
 * @className OrderController
 * @date: 2022/9/27 22:55
 * @description:
 */
@RestController
@RequestMapping("/order")
public class OrderController implements OrderApi {
  @Autowired
  private IOrderService orderService;
  @Override
  public Boolean createOrder(OrderInfo orderInfo) {
    String commodityCode = orderInfo.getCommodityCode();
    int count = orderInfo.getCount();
    long unitPrice = orderInfo.getUnitPrice();
    String userId = orderInfo.getUserId();
    return orderService.createOrder(userId, commodityCode, count, unitPrice);
  }
}
package com.example.orderapi.api;
import com.example.orderapi.model.OrderInfo;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
/**
 * @author zouwei
 * @className OrderApi
 * @date: 2022/9/27 22:57
 * @description:
 */
public interface OrderApi {
  @PutMapping("/create")
  Boolean createOrder(@RequestBody OrderInfo orderInfo);
}
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接下来，就剩下awesome-storage服务了：

package com.example.awesomestorage.service.impl;
import com.example.awesomestorage.dao.mapper.StockEnhanceMapper;
import com.example.awesomestorage.service.IStockService;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import javax.annotation.Resource;
/**
 * @author zouwei
 * @className StockServiceImpl
 * @date: 2022/9/28 00:06
 * @description:
 */
@Service
public class StockServiceImpl implements IStockService {
  @Resource
  private StockEnhanceMapper stockEnhanceMapper;
  @Transactional
  @Override
  public Boolean deductStock(String commodityCode, int count) {
    // 扣减库存，判断影响行数是否大于0
    // sql如下： update stock_tbl set count = count - #{count,jdbcType=INTEGER} where commodity_code = #{commodityCode,jdbcType=VARCHAR} and count <![CDATA[ >= ]]> #{count,jdbcType=INTEGER}
    return stockEnhanceMapper.deductStock(commodityCode, count) > 0;
  }
}
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package com.example.awesomestorage.controller;
import com.example.awesomestorage.service.IStockService;
import com.example.storageapi.api.StockApi;
import com.example.storageapi.model.OrderInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
 * @author zouwei
 * @className StockController
 * @date: 2022/9/28 00:23
 * @description:
 */
@RestController
@RequestMapping("/stock")
public class StockController implements StockApi {
  @Autowired
  private IStockService stockService;
  @Override
  public Boolean deductStock(OrderInfo orderInfo) {
    String commodityCode = orderInfo.getCommodityCode();
    int count = orderInfo.getCount();
    return stockService.deductStock(commodityCode, count);
  }
}
package com.example.storageapi.api;
import com.example.storageapi.model.OrderInfo;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
/**
 * @author zouwei
 * @className StockApi
 * @date: 2022/9/28 00:26
 * @description:
 */
public interface StockApi {
  @PostMapping("/deduct")
  Boolean deductStock(@RequestBody OrderInfo orderInfo);
}
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至此，这几个服务的核心代码就全部搞定，我们千万别忘记了在项目入口类中加上对应的注解，比如awesome-business入口类：

package com.example.awesomebusiness;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
// 开启nacos，不过仅仅使用服务发现，不需要注册
@EnableDiscoveryClient(autoRegister = false)
// 开启OpenFeign
@EnableFeignClients
@SpringBootApplication
public class AwesomeBusinessApplication {
  public static void main(String[] args) {
    SpringApplication.run(AwesomeBusinessApplication.class, args);
  }
}
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awesome-order的入口类有些许不同：

package com.example.awesomeorder;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
// 增加mybatis的MapperScan注解
@MapperScan(basePackages = "com.example.awesomeorder.dao.mapper")
// RPC调用才需要OpenFeign
@EnableFeignClients
// 既要注册当前服务，也要发现其他服务，比如storage库存服务
@EnableDiscoveryClient
@SpringBootApplication
public class AwesomeOrderApplication {
  public static void main(String[] args) {
    SpringApplication.run(AwesomeOrderApplication.class, args);
  }
}
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如果小伙伴们对于mybatis的配置有疑虑的话，可以查看博客：手把手教你springboot集成mybatis；另外我怕也会将当前项目代码上传到github，想了解的小伙伴可以自己下载：awesome-seata。

小结

通过以上示例，我们需要了解到以下几点，才能帮助我们更好地继承seata AT模式到我们的项目当中：

1.TM只负责全局事务的管理，比如全局事务的开启、提交或回滚；

2.TM可以和RM共存，也就是说，一个服务中，可以既有TM，也有RM；

3.RM只负责分支事务的管理，比如分支事务的注册、上报、提交或回滚；

4.多个分支事务是否在同一个分布式事务当中，是通过XID来判断的，XID是通过RPC来传递的；

5.TC相当于一个传话筒和记事本，负责记录和维护全局事务和分支事务的状态，以及下发TM提交或回滚的指令给到RM；

6.在RM当中是不需要使用@GlobalTransactional注解的，只需要使用@Transactional注解来保证分支事务的原子性；

7.所有的RM服务都需要有undo_log数据表，这样才能使用AT模式；

Spring Cloud集成分布式事务框架Seata 1.5.2（三）

小结

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