正确处理Hibernate自定义连接表与多对多关系映射

// Alarm.java (部分代码)
@Entity
@Table(name = "alarm")
public class Alarm {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Integer alarmId;

    // ... 其他属性

    @OneToMany(orphanRemoval = true, cascade = {CascadeType.REMOVE, CascadeType.MERGE})
    private List<ListAlarmJoinTable> alarmLists; // 问题所在

    // ...
}

// AlarmList.java (部分代码)
@Entity
@Table(name = "alarm_list")
public class AlarmList {
    @Id
    private String name;

    // ... 其他属性

    @OneToMany(orphanRemoval = true, cascade = {CascadeType.REMOVE, CascadeType.MERGE})
    private List<ListAlarmJoinTable> alarms; // 问题所在

    // ...
}

// ListAlarmJoinTable.java
@Entity
@Table(name = "list_alarms_join_table")
public class ListAlarmJoinTable {
    @EmbeddedId
    private AlarmListId id;
    private int position;

    // ...
}

// AlarmListId.java
@Embeddable
public class AlarmListId implements Serializable {
    private Integer alarmId; // 问题所在
    private String listId;   // 问题所在

    // ... 构造器, getter/setter
}

import jakarta.persistence.Embeddable;
import jakarta.persistence.ManyToOne;
import jakarta.persistence.FetchType; // 注意引入FetchType
import lombok.Getter;
import lombok.Setter;
import lombok.NoArgsConstructor;
import lombok.AllArgsConstructor;
import java.io.Serializable;
import java.util.Objects; // 用于hashCode和equals

@Embeddable
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class AlarmListId implements Serializable {

    // 明确指出这是一个ManyToOne关系，指向Alarm实体
    @ManyToOne(optional = false, fetch = FetchType.LAZY)
    private Alarm alarm;

    // 明确指出这是一个ManyToOne关系，指向AlarmList实体
    @ManyToOne(optional = false, fetch = FetchType.LAZY)
    private AlarmList list;

    // IMPORTANT: 必须实现 hashCode() 和 equals() 方法
    // 对于 @Embeddable 类作为 @EmbeddedId 使用时，这是保证集合操作和实体识别正确性的关键。
    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        AlarmListId that = (AlarmListId) o;
        return Objects.equals(alarm, that.alarm) &&
               Objects.equals(list, that.list);
    }

    @Override
    public int hashCode() {
        return Objects.hash(alarm, list);
    }
}

// Alarm.java (修正后)
@Entity
@Table(name = "alarm")
public class Alarm {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Integer alarmId;

    // ... 其他属性

    // 使用 mappedBy 指向 ListAlarmJoinTable 中 id 字段的 alarm 属性
    @OneToMany(orphanRemoval = true, cascade = {CascadeType.REMOVE, CascadeType.MERGE}, mappedBy = "id.alarm")
    private List<ListAlarmJoinTable> alarmLists;

    // ...
}

// AlarmList.java (修正后)
@Entity
@Table(name = "alarm_list")
public class AlarmList {
    @Id
    private String name;

    // ... 其他属性

    // 使用 mappedBy 指向 ListAlarmJoinTable 中 id 字段的 list 属性
    @OneToMany(orphanRemoval = true, cascade = {CascadeType.REMOVE, CascadeType.MERGE}, mappedBy = "id.list")
    private List<ListAlarmJoinTable> alarms;

    // ...
}