Differences among POJO vs Bean vs DTO/VO vs Model vs Domain Class | Deep Drive into practical knowledge :
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Pojo :::
POJO is an acronym for Plain Old Java Object. The name is used to emphasize that the object in question is an ordinary Java Object, not a special object.
Should -
1. Class public
2. private data members
3. getter and setters method
4. No arg or Default Constructor
They were introduced in EJB 3.0 by Sun microsystems.
A POJO should not:
Extend prespecified classes, Ex: public class GFG extends javax.servlet.http.HttpServlet { … } is not a POJO class.
Implement prespecified interfaces, Ex: public class Bar implements javax.ejb.EntityBean { … } is not a POJO class.
Contain prespecified annotations, Ex: @javax.persistence.Entity public class Baz { … } is not a POJO class.
Beans
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Beans are special type of Pojos. There are some restrictions on POJO to be a bean.
All JavaBeans are POJOs but not all POJOs are JavaBeans.
Serializable i.e. they should implement Serializable interface. Still some POJOs who don’t implement Serializable interface are called POJOs beacause Serializable is a marker interface and therefore not of much burden.
Value Object/VO
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A Value Object or VO is an object such as java.lang.Integer that hold values (hence value objects).
DTO
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Instead of performing many remote calls on EJBs, the idea was to encapsulate data in a value object that could be transferred over the network: a Data Transfer Object.
Model
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The model class is nothing it is just a different naming convention for DTOs they also hold Data but usually, they are used on the frontend side and not so close to the Database side.
Domain
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Your main Business classes, nothing but a POJO class.
Thanks & Regards,
Debu Paul
14 окт 2024
