Spring-boot读书笔记一POJO class

POJO Definition
POJO = Plain Old Java Object

A POJO is a simple Java class with no special restrictions, following basic conventions:

// Simple POJO example
public class User {
    private String name;
    private int age;
    
    // Default constructor
    public User() {}
    
    // Constructor with parameters
    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }
    
    // Getters and setters
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    
    public int getAge() { return age; }
    public void setAge(int age) { this.age = age; }
}

POJO Requirements

• No inheritance restrictions - doesn't extend framework-specific classes
• No interface requirements - doesn't implement framework interfaces
• No annotations required - works without special annotations
• Serializable - can be easily serialized/deserialized
• Default constructor - typically has a no-arg constructor

POJO vs Normal Class
|POJO |Regular Class
|Simple data container |Can have complex business logic
|Follows JavaBean conventions |No specific conventions
|Framework-agnostic |May depend on frameworks
|Easy serialization |May have serialization issues
|Minimal dependencies |Can have many dependencies

Special Effects of POJOs
1,Framework Compatibility: Works seamlessly with:

• JSON/XML serialization (Jackson, GSON)
• ORM frameworks (Hibernate, JPA)
• Spring Framework binding
• Reflection-based tools

2,Your AppProperties Example: While it has Spring annotations, the underlying structure follows POJO principles - simple fields, getters, and constructor.

Data Transfer: Perfect for:

• API responses/requests
• Database entity mapping
• Configuration binding
• Inter-service communication

POJOs provide simplicity, portability, and framework independence, making them ideal for data representation and transfer scenarios.