解决JPA双向循环引用：Jackson注解的有效应用与最佳实践

// Parent.java (示例)
public class Parent {
    // ...
    @OneToMany(mappedBy = "parent")
    @JsonIgnore // 忽略children字段的序列化
    private List<Child> children;
    // ...
}

// Child.java (示例)
public class Child {
    // ...
    @ManyToOne
    @JoinColumn(name = "parent_id")
    private Parent parent;
    // ...
}

import com.fasterxml.jackson.annotation.JsonBackReference;
import com.fasterxml.jackson.annotation.JsonManagedReference;
import jakarta.persistence.*;
import java.util.ArrayList;
import java.util.List;

// Parent.java
@Entity
@Table(name = "parents")
public class Parent {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    // Parent是主控方，拥有Child列表
    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
    @JsonManagedReference // 标记为管理方，序列化时包含children
    private List<Child> children = new ArrayList<>();

    // 构造函数、Getter和Setter
    public Parent() {}

    public Parent(String name) {
        this.name = name;
    }

    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public List<Child> getChildren() { return children; }
    public void setChildren(List<Child> children) { this.children = children; }

    public void addChild(Child child) {
        children.add(child);
        child.setParent(this);
    }

    public void removeChild(Child child) {
        children.remove(child);
        child.setParent(null);
    }
}

import com.fasterxml.jackson.annotation.JsonBackReference;
import jakarta.persistence.*;

// Child.java
@Entity
@Table(name = "children")
public class Child {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    // Child是被拥有方，反向引用Parent
    @ManyToOne(fetch = FetchType.LAZY) // 建议使用懒加载
    @JoinColumn(name = "parent_id")
    @JsonBackReference // 标记为反向引用方，序列化时忽略parent
    private Parent parent;

    // 构造函数、Getter和Setter
    public Child() {}

    public Child(String name) {
        this.name = name;
    }

    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public Parent getParent() { return parent; }
    public void setParent(Parent parent) { this.parent = parent; }
}