POJO (Plain Ordinary Java Object) is an ordinary Java class. The type with some getter/setter methods can be called POJO.
The actual meaning is ordinary JavaBeans (simple entity classes), which are characterized by assistance classes that support business logic.
The function of the POJO class is to facilitate programmers to use data tables in the database. For programmers, it is very convenient to use the POJO class as an object, and to conveniently call its get and set methods.
But business methods are not allowed, and methods such as connection cannot be carried, that is, it does not contain business logic or persistence logic, etc.
According to Sun's definition, JavaBean is a reusable software component. In fact, JavaBean is a Java class that encapsulates properties and methods to become an object with a certain function or handles a certain business, referred to as a bean.
JavaBean is a reusable component written in JAVA language. Its method naming, construction and behavior must conform to specific conventions:
This class must have a public default constructor.
The properties of this class are accessed using getters and setters, and other methods follow standard naming conventions.
This class should be serializable.
Because these requirements mainly rely on convention rather than implementing interfaces, many developers regard JavaBeans as POJOs that comply with specific naming conventions.
The task of JavaBean is: "Write once, run anywhere, reuse everywhere", that is, "write once, execute anywhere, and reuse anywhere."
JavaBeans can be divided into two types: one is a JavaBean with a user interface (UI, User Interface); the other is a JavaBean without a user interface and is mainly responsible for processing transactions (such as data calculations, manipulating the database). JSP usually accesses the latter JavaBean.
In short, when a Pojo is serializable, has a parameterless constructor, and uses getter and setter methods to access properties, it is a JavaBean.
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