Seata 分布式事务解决方案

@Configuration
public class DataSourceConfig {

    @Bean
    @ConfigurationProperties("spring.datasource.druid")
    public DruidDataSource druidDataSource() {
        return new DruidDataSource();
    }

    @Bean
    public DataSource dataSource(DruidDataSource druidDataSource) {
        return new DataSourceProxy(druidDataSource);
    }

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

@Entity
@Table(name = "account")
public class Account {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "user_id")
    private String userId;

    @Column(name = "money")
    private BigDecimal money;

    // getter and setter methods
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public BigDecimal getMoney() {
        return money;
    }

    public void setMoney(BigDecimal money) {
        this.money = money;
    }
}

@Repository
public interface AccountRepository extends JpaRepository<Account, Long> {

    @Modifying
    @Query("UPDATE Account a SET a.money = a.money - :amount WHERE a.userId = :userId")
    int debit(@Param("userId") String userId, @Param("amount") BigDecimal amount);

    @Modifying
    @Query("UPDATE Account a SET a.money = a.money + :amount WHERE a.userId = :userId")
    int credit(@Param("userId") String userId, @Param("amount") BigDecimal amount);

    Optional<Account> findByUserId(String userId);
}

@Service
public class AccountService {

    @Autowired
    private AccountRepository accountRepository;

    /**
     * 扣减账户余额
     * @param userId 用户ID
     * @param money 扣减金额
     * @return 操作结果
     */
    @GlobalTransactional(rollbackFor = Exception.class)
    public boolean debit(String userId, BigDecimal money) {
        Account account = accountRepository.findByUserId(userId)
            .orElseThrow(() -> new RuntimeException("账户不存在"));

        if (account.getMoney().compareTo(money) < 0) {
            throw new RuntimeException("账户余额不足");
        }

        int result = accountRepository.debit(userId, money);
        if (result <= 0) {
            throw new RuntimeException("扣减失败");
        }

        return true;
    }

    /**
     * 增加账户余额
     * @param userId 用户ID
     * @param money 增加金额
     * @return 操作结果
     */
    @GlobalTransactional(rollbackFor = Exception.class)
    public boolean credit(String userId, BigDecimal money) {
        int result = accountRepository.credit(userId, money);
        if (result <= 0) {
            throw new RuntimeException("增加失败");
        }

        return true;
    }

    /**
     * 转账操作
     * @param fromUserId 转出用户ID
     * @param toUserId 转入用户ID
     * @param money 转账金额
     * @return 操作结果
     */
    @GlobalTransactional(rollbackFor = Exception.class)
    public boolean transfer(String fromUserId, String toUserId, BigDecimal money) {
        // 扣减转出账户
        debit(fromUserId, money);

        // 增加转入账户
        credit(toUserId, money);

        return true;
    }
}

@RestController
@RequestMapping("/api/account")
public class AccountController {

    @Autowired
    private AccountService accountService;

    /**
     * 转账接口
     */
    @PostMapping("/transfer")
    public ResponseEntity<String> transfer(@RequestParam String fromUserId,
                                         @RequestParam String toUserId,
                                         @RequestParam BigDecimal money) {
        try {
            boolean result = accountService.transfer(fromUserId, toUserId, money);
            if (result) {
                return ResponseEntity.ok("转账成功");
            } else {
                return ResponseEntity.badRequest().body("转账失败");
            }
        } catch (Exception e) {
            return ResponseEntity.badRequest().body("转账失败: " + e.getMessage());
        }
    }

    /**
     * 查询账户余额
     */
    @GetMapping("/balance/{userId}")
    public ResponseEntity<BigDecimal> getBalance(@PathVariable String userId) {
        try {
            Account account = accountService.findByUserId(userId);
            return ResponseEntity.ok(account.getMoney());
        } catch (Exception e) {
            return ResponseEntity.badRequest().body(BigDecimal.ZERO);
        }
    }
}

@SpringBootApplication
@EnableTransactionManagement
public class SeataDemoApplication {

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

@GlobalTransactional(rollbackFor = Exception.class)
public boolean transfer(String fromUserId, String toUserId, BigDecimal money) {
    // 扣减转出账户
    debit(fromUserId, money);

    // 增加转入账户
    credit(toUserId, money);

    // 模拟异常，触发回滚
    if (money.compareTo(new BigDecimal("500")) > 0) {
        throw new RuntimeException("转账金额过大，触发回滚");
    }

    return true;
}

@Service
public class OrderService {

    @Autowired
    private OrderRepository orderRepository;

    @GlobalTransactional(rollbackFor = Exception.class)
    public boolean createOrder(String userId, BigDecimal amount) {
        Order order = new Order();
        order.setUserId(userId);
        order.setAmount(amount);
        order.setStatus("PENDING");
        order.setCreateTime(new Date());

        orderRepository.save(order);

        // 调用库存服务扣减库存
        inventoryService.decreaseStock(order.getProductId(), order.getQuantity());

        // 调用账户服务扣减余额
        accountService.debit(userId, amount);

        // 更新订单状态
        order.setStatus("COMPLETED");
        orderRepository.save(order);

        return true;
    }
}

@Service
public class InventoryService {

    @Autowired
    private InventoryRepository inventoryRepository;

    @GlobalTransactional(rollbackFor = Exception.class)
    public boolean decreaseStock(String productId, Integer quantity) {
        Inventory inventory = inventoryRepository.findByProductId(productId)
            .orElseThrow(() -> new RuntimeException("商品不存在"));

        if (inventory.getStock() < quantity) {
            throw new RuntimeException("库存不足");
        }

        inventory.setStock(inventory.getStock() - quantity);
        inventoryRepository.save(inventory);

        return true;
    }
}