问题描述:

I don't understand the difference between POJO and DTO in Java. I have read the article here: What is the Difference Between POJO (Plain Old Java Object) and DTO (Data Transfer Object)? . But I still don't understand the code implementation between them, what makes them different. Can you give the code example for each of them? Thank you so much before!

网友答案:

POJO means Plain Old Java Object. A POJO is an object that doesn't need to implement any specific interface or extend some specific class to be used by a framework. The term has been coined, if I remember correctly, to react against EJB1 and EJB2 which imposed a lot of constraints on the way you had to write beans to make them EJBs. POJO is more a marketing term than a technical term.

DTO means Data Transfer Object. A DTO is an object that is used to transfer data between layers of an application, typically over the network. It often consists in a POJO (i.e. a simple Java class) containing fields and getters.

网友答案:

A Plain Old Java Object or POJO is a term initially introduced to designate a simple lightweight Java object, not implementing any javax.ejb interface in contrast to Entity beans Now a days , POJO term is used for any simple object with no extra fancy annotation like third party annotations etc

DTO is an object whose responsibility is just to encapsulate data in a value object . It will just have instance members and corresponding getters and setters. Generally they used to represent the row in data store. While pojo include some more methods that doing some business processing on them

网友答案:

Actually, POJO is more general. Any class which has private serializable fields, getters and setter for each field and doesnt extend other class or implement an interface may be called POJO.

DTO is an object which uses some data object (for example, JPA entity object) to transfer data to another tier of your application (for example, if entity1 object has reference to other entity2, DTO can replace entity2 reference by its entity2.id.toString or other entity2 field).

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