概述

Seata 是一款開源的分布式事務解決方案，致力于提供高性能和簡單易用的分布式事務服務。

更多的介紹可以參考官方文檔：Seata快速入門
本篇主要是介紹Spring Cloud Alibaba + JPA 整合 Seata 的過程

安裝Seata

• 下載Seata，打開 https://github.com/seata/seata/releases，現在最新的是1.3.0，所以選擇seata-server-1.3.0.tar.gz 進行下載，放到/opt
• 解壓Seata到/usr/local目錄下

cd /opt tar -zxvf seata-server-1.3.0.tar.gz -C /usr/local cd /usr/local/seata/

• 這邊采用file單機模式（db模式相對麻煩一點，以后再另外介紹，從簡單的先開始），直接運行命令啟動即可

./bin/seata-server.sh

看到下面這個提示，說明啟動成功，默認端口號8091

接下來介紹Spring Cloud Alibaba 接入Seata

業務場景

假設當前存在2個微服務：訂單服務、支付服務。

• 用戶下單時，訂單服務需要調用支付服務進行扣款
• 當余額充足時下單成功，并全局提交事務
• 當余額不足時下單失敗，并全局回滾事務

版本說明

框架版本號

Spring Boot	2.1.13.RELEASE
Spring Cloud	Greenwich.SR6
Spring Cloud Alibaba	2.1.3.RELEASE
MySQL	8.0.11

創建父工程

創建父工程 hello-alibaba-seata，并引入依賴：

<dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring-cloud-version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-alibaba-dependencies</artifactId><version>${spring-cloud-alibaba-version}</version><type>pom</type><scope>import</scope></dependency></dependencies> </dependencyManagement><dependencies><!--Spring Boot--><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-data-jpa</artifactId></dependency><!--Nacos--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId></dependency><!--Seata--><dependency><groupId>com.alibaba.cloud</groupId><artifactId>spring-cloud-starter-alibaba-seata</artifactId></dependency><!--MySQL--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>${mysql.version}</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency> </dependencies>

創建公共服務 common-server

該工程主要封裝公共的VO，由于測試場景比較簡單，目前只有一個類

@Data @Builder public class ReduceAmountDto {private Long userId;private Integer amount; }

創建支付服務 pay-order

在訂單-支付的關系中，支付服務相當于provider，訂單服務相當于consumer。因此，這邊我們先創建支付服務。

• 引入 common-server 依賴

<dependencies><dependency><groupId>com.train</groupId><artifactId>common-server</artifactId><version>${project.parent.version}</version></dependency></dependencies>

• 創建賬戶 Entity

@Data @Entity @Table(name = "t_account") public class AccountInfo {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;/*** 用戶id*/@Column(name = "user_id")private Long userId;/*** 余額*/@Column(name = "amount")private Integer amount; }

• 創建Dao

public interface AccountDao extends CrudRepository<AccountInfo, Long> {/*** 根據userId獲取賬戶信息*/@Query(value = "SELECT a FROM AccountInfo a where a.userId = :userId")AccountInfo getByUserId(@Param("userId") Long userId);/*** 扣減賬戶余額*/@Modifying@Query("UPDATE AccountInfo SET amount = amount - :amount WHERE userId = :userId")Integer reduceAmount(@Param("userId") Long userId, @Param("amount") Integer amount); }

• 創建 Service

@Service public class PayServiceImpl implements PayService {@Autowiredprivate AccountDao accountDao;@Override@Transactional(rollbackFor = Exception.class)public void reduceAmount(Long userId, Integer reduceAmount) throws Exception {checkAmount(userId, reduceAmount);accountDao.reduceAmount(userId, reduceAmount);}private void checkAmount(Long userId, Integer reduceAmount) throws Exception {AccountInfo accountInfo = accountDao.getByUserId(userId);if (accountInfo == null){throw new Exception("找不到賬戶信息");}if (accountInfo.getAmount() < reduceAmount){throw new Exception("余額不足");}} }

• 創建 controller

@RestController @RequestMapping("/pay") public class PayController {@Autowiredprivate PayService payService;@PostMapping("/reduceAmount")public String reduceAmount(@RequestBody ReduceAmountDto input) throws Exception {payService.reduceAmount(input.getUserId(), input.getAmount());return "扣款成功";} }

• application.yml

server:port: 8012spring:application:name: pay-serverjpa:database: mysqldatasource:url: jdbc:mysql://192.168.25.129:3306/pay_db?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=UTF-8&useSSL=falseusername: testpassword: 123456driver-class-name: com.mysql.cj.jdbc.Drivercloud:nacos:discovery:server-addr: 192.168.25.131:8848 management:endpoints:web:exposure:include: "*"seata:enabled: trueapplication-id: ${spring.application.name}tx-service-group: my_test_tx_groupservice:vgroup-mapping:my_test_tx_group: defaultgrouplist:default: 192.168.25.131:8091config:type: filefile:name: file.confregistry:type: filefile:name: file.confenable-auto-data-source-proxy: true

注意：如果用的不是MySQL8，就要改下 driver-class-name

創建訂單服務 order-server

• 引入 common-server 依賴

<dependencies><dependency><groupId>com.train</groupId><artifactId>common-server</artifactId><version>${project.parent.version}</version></dependency></dependencies>

• 創建訂單 Entity

@Data @Entity @Table(name = "t_order") public class Orders {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;/*** 用戶id*/@Column(name = "user_id")private Long userId;/*** 金額*/@Column(name = "amount")private Integer amount; }

• 創建訂單 Dao

public interface OrdersDao extends CrudRepository<Orders, Long> { }

• 創建 Service

@Service @Slf4j public class OrderServiceImpl implements OrderService {@Autowiredprivate OrdersDao orderDao;@Autowiredprivate RestTemplate restTemplate;@Override@GlobalTransactionalpublic void save(Orders order) {orderDao.save(order);//扣款String reduceUrl = "http://pay-server/pay/reduceAmount";ReduceAmountDto input = ReduceAmountDto.builder().userId(order.getUserId()).amount(order.getAmount()).build();String result = restTemplate.postForObject(reduceUrl, input, String.class);log.info("調用pay-server結果：" + result);} }

@GlobalTransactional 表示開啟Seata全局事務

• 創建 controller

@RestController @RequestMapping("/order") public class OrderController {@Autowiredprivate OrderService orderService;@RequestMapping("/save")public String save(@RequestBody Orders order){orderService.save(order);return "操作結束";} }

測試

啟動Nacos

啟動Seata

啟動pay-server

啟動order-server

調用創建訂單接口 http://localhost:8011/order/save ，構造相應的測試數據進行測試就行

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