如何在内部UUID和外部随机字符串ID之间建立可靠映射：最佳实践与误区

import java.util.UUID;

// 假设这是你的Customer实体类
public class Customer {
    private UUID uuid; // 内部UUID
    private String externalId; // 外部API的ID
    private String name;

    // 构造函数, getter/setter省略
    public Customer(UUID uuid, String externalId, String name) {
        this.uuid = uuid;
        this.externalId = externalId;
        this.name = name;
    }

    public UUID getUuid() {
        return uuid;
    }

    public String getExternalId() {
        return externalId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

// 假设这是你的CustomerRepository接口
interface CustomerRepository {
    Customer findByUuid(UUID uuid);
    Customer save(Customer customer);
    // ... 其他CRUD操作
}

// 假设这是你的第三方服务接口
interface ThirdPartyService {
    void updateCustomer(String externalId, String newName);
    // ... 其他第三方API调用
}

public class CustomerService {

    private final CustomerRepository customerRepository;
    private final ThirdPartyService thirdPartyService;

    public CustomerService(CustomerRepository customerRepository, ThirdPartyService thirdPartyService) {
        this.customerRepository = customerRepository;
        this.thirdPartyService = thirdPartyService;
    }

    /**
     * 更新客户名称，通过内部UUID查找外部ID，然后调用第三方服务。
     * @param customerUuid 内部客户UUID
     * @param newName 新的客户名称
     */
    public void updateCustomerName(UUID customerUuid, String newName) {
        Customer customer = customerRepository.findByUuid(customerUuid);
        if (customer != null) {
            // 更新内部名称（如果需要）
            customer.setName(newName);
            customerRepository.save(customer); // 持久化内部变更

            // 使用外部ID调用第三方服务
            thirdPartyService.updateCustomer(customer.getExternalId(), newName);
            System.out.println("Customer " + customerUuid + " updated with new name: " + newName + " in both internal and external systems.");
        } else {
            System.out.println("Customer with UUID " + customerUuid + " not found.");
        }
    }

    /**
     * 示例：从第三方API获取数据并保存到本地
     * @param externalId 第三方API返回的ID
     * @param name 第三方API返回的名称
     */
    public void createOrUpdateCustomerFromThirdParty(String externalId, String name) {
        // 实际应用中可能需要先查询是否存在externalId，这里简化为直接创建
        UUID internalUuid = UUID.randomUUID(); // 生成新的内部UUID
        Customer newCustomer = new Customer(internalUuid, externalId, name);
        customerRepository.save(newCustomer);
        System.out.println("New customer created with internal UUID: " + internalUuid + " and external ID: " + externalId);
    }

    public static void main(String[] args) {
        // 模拟依赖
        CustomerRepository mockCustomerRepository = new CustomerRepository() {
            private Customer storedCustomer; // 简化存储

            @Override
            public Customer findByUuid(UUID uuid) {
                return (storedCustomer != null && storedCustomer.getUuid().equals(uuid)) ? storedCustomer : null;
            }

            @Override
            public Customer save(Customer customer) {
                this.storedCustomer = customer;
                return customer;
            }
        };

        ThirdPartyService mockThirdPartyService = new ThirdPartyService() {
            @Override
            public void updateCustomer(String externalId, String newName) {
                System.out.println("Calling 3rd party API: updateCustomer(" + externalId + ", " + newName + ")");
                // 模拟第三方API调用
            }
        };

        CustomerService service = new CustomerService(mockCustomerRepository, mockThirdPartyService);

        // 模拟从第三方API获取并保存客户
        String thirdPartyCustomerId = "ppkk1231whatupeverybodyhohohaharandomrandom";
        service.createOrUpdateCustomerFromThirdParty(thirdPartyCustomerId, "patrick");

        // 模拟通过内部UUID更新客户
        UUID internalCustomerId = mockCustomerRepository.findByUuid(mockCustomerRepository.findByUuid(null).getUuid()).getUuid(); // 获取刚才创建的UUID
        service.updateCustomerName(internalCustomerId, "Patrick Star");
    }
}