SpringBoot PO VO BO POJO实战指南

基于Spring Boot的PO（持久化对象）

以下是一些基于Spring Boot的PO（持久化对象）实例示例，涵盖不同场景和功能：

基础PO类示例

@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String email;
}

@Entity
@Table(name = "products")
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private BigDecimal price;
}

关联关系示例

@Entity
@Table(name = "orders")
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne
    @JoinColumn(name = "user_id")
    private User user;
}

@Entity
@Table(name = "order_items")
public class OrderItem {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ManyToOne
    @JoinColumn(name = "order_id")
    private Order order;

    @ManyToOne
    @JoinColumn(name = "product_id")
    private Product product;
}

继承关系示例

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "vehicle_type")
public abstract class Vehicle {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String manufacturer;
}

@Entity
@DiscriminatorValue("CAR")
public class Car extends Vehicle {
    private int numberOfDoors;
}

复杂类型处理

@Entity
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Embedded
    private Address address;
}

@Embeddable
public class Address {
    private String street;
    private String city;
    private String zipCode;
}

审计字段示例

@Entity
@EntityListeners(AuditingEntityListener.class)
public class Document {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @CreatedDate
    private LocalDateTime createdAt;

    @LastModifiedDate
    private LocalDateTime updatedAt;
}

枚举类型处理

@Entity
public class Order {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Enumerated(EnumType.STRING)
    private OrderStatus status;
}

public enum OrderStatus {
    PENDING, PROCESSING, COMPLETED, CANCELLED
}

集合类型处理

@Entity
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @ElementCollection
    @CollectionTable(name = "student_phone_numbers", joinColumns = @JoinColumn(name = "student_id"))
    private Set<String> phoneNumbers = new HashSet<>();
}

JSON类型处理

@Entity
public class Product {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(columnDefinition = "json")
    private String specifications;
}

多租户示例

@Entity
public class TenantAwareEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "tenant_id")
    private String tenantId;
}

软删除示例

@Entity
public class Customer {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "is_deleted")
    private boolean deleted;
}

版本控制示例

@Entity
public class BankAccount {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Version
    private Long version;
}

自定义ID生成器

@Entity
public class Invoice {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    private String id;
}

时间处理

@Entity
public class Event {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Temporal(TemporalType.TIMESTAMP)
    private Date startTime;
}

大对象处理

@Entity
public class Document {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Lob
    private byte[] content;
}

索引示例

@Entity
@Table(name = "employees", indexes = @Index(columnList = "department_id"))
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private Long