从第三方 Web 服务和应用程序的专用数据库检索客户字段时的 CustomerDAO 替代方案

Question

I have a Customer class. Its private field is a CustomerDAO interface which database-access methods are called by myCustomer.getAge() for example. CustomerDAO retrieves data from the application's dedicated database.

The problem is that a few fields of Customer now have to be retrieved from a third-party web-service. Logically calling some web-service doesn't belong to CustomerDAO (which is intended for communicating with a single database, right?).

What is the industry recommended approach in such cases?

Shall I just add another field CustomerWebServiceDAO (as interface) to Customer ? And my Customer would use internally two different instances ( CustomerDAO and CustomerWebServiceDAO ). So DAO gets split into 2 separate classes... What if next I need access to another Web-service plus an additional database? What better solution/pattern can be used?

Adding web-service methods to initial CustomerDAO interface would mix database access with web-service access, which I think is not good.

Answer 1

If I understand your question right you need to have a database service which has all GRUD operation of Customer and assume it will be called CustomerDBDao and another service Called CustomerAPIDao which is responsible of all web service operations and all services is called in a general service called CustomerDAO which is filling data from both services and generate One Unified POJO this concept is called adapter design patter

https://www.tutorialspoint.com/design_pattern/adapter_pattern.htm