springcloud中事务使用代码

在 Spring Cloud 中，使用分布式事务需要结合多个组件一起使用，包括 Spring Boot、Spring Cloud、分布式事务管理器（例如：Atomikos、Bitronix、Narayana 等）和数据库（例如：MySQL、PostgreSQL 等）。

下面是一个使用 Spring Cloud 和 Atomikos 实现分布式事务的示例代码：

1. 添加依赖

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-atomikos</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

2. 配置数据源和事务管理器

spring:
  jta:
    atomikos:
      transaction-manager-id: tm
      log-dir: /var/log/atomikos
      max-actives: 50
      max-idle: 5
      min-idle: 1
      max-pool-size: 50
      min-pool-size: 5
      allow-employee-recovery: true
      default-timeout: 60
      resource:
        xaDataSourceClassName: com.mysql.cj.jdbc.MysqlXADataSource
        uniqueResourceName: main
        xaProperties:
          user: root
          password: root
          url: jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false
eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/

3. 配置 JPA 和事务管理器

@Configuration
@EnableJpaRepositories(basePackages = "com.example.demo.repository")
@EnableTransactionManagement
public class JpaConfig {
    @Bean
    public JtaTransactionManager jtaTransactionManager() {
        return new JtaTransactionManager(atomikosTransactionManager());
    }

    @Bean(initMethod = "init", destroyMethod = "close")
    public UserTransactionManager atomikosTransactionManager() {
        UserTransactionManager atomikosTransactionManager = new UserTransactionManager();
        atomikosTransactionManager.setForceShutdown(false);
        return atomikosTransactionManager;
    }

    @Bean
    public UserTransaction atomikosUserTransaction() throws SystemException {
        return new UserTransactionImp();
    }

    @Bean
    public Properties jpaProperties() {
        Properties properties = new Properties();
        properties.setProperty("hibernate.transaction.jta.platform", AtomikosJtaPlatform.class.getName());
        properties.setProperty("hibernate.hbm2ddl.auto", "update");
        properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQL5InnoDBDialect");
        properties.setProperty("hibernate.show_sql", "true");
        properties.setProperty("hibernate.format_sql", "true");
        return properties;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter, Properties jpaProperties) {
        LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource);
        em.setJpaVendorAdapter(jpaVendorAdapter);
        em.setJpaProperties(jpaProperties);
        em.setPackagesToScan("com.example.demo.entity");
        return em;
    }

    @Bean
    public PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactory);
        return transactionManager;
    }

    @Bean
    public JpaVendorAdapter jpaVendorAdapter() {
        HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        adapter.setDatabase(Database.MYSQL);
        adapter.setShowSql(true);
        adapter.setGenerateDdl(false);
        adapter.setDatabasePlatform("org.hibernate.dialect.MySQL5InnoDBDialect");
        return adapter;
    }
}

4. 定义业务服务

@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;

    @Transactional
    public void saveUser(User user) {
        userRepository.save(user);
    }
}

5. 定义控制器

@RestController
public class UserController {
    @Autowired
    private UserService userService;

    @PostMapping("/user")
    public void saveUser(@RequestBody User user) {
        userService.saveUser(user);
    }
}

以上就是一个基于 Spring Cloud 和 Atomikos 实现分布式事务的示例代码。需要注意的是，分布式事务的实现需要结合具体的技术栈和业务场景来综合考虑。