如何使用單獨的 Mysql 表實現帶有 JPA 的枚舉

Question

我真的是使用 JPA 的新手，但仍然不知道如何實現這一點，我很樂意提供任何建議或解決方案。

Mysql 表：

CREATE TABLE REAL_STATE_TYPES (
real_state_type_id INT(6) NOT NULL,
real_state_type VARCHAR(50) NOT NULL,
PRIMARY KEY (real_state_type_id)
);

CREATE TABLE REAL_STATES (
address VARCHAR(30) NOT NULL,
admin_id VARCHAR(15) NOT NULL,
real_state_type_id INT(6) NOT NULL,
block VARCHAR(3) NOT NULL,
internal_id INT(5) NOT NULL,
PRIMARY KEY (address, block, internal_id),
FOREIGN KEY (real_state_type_id) REFERENCES REAL_STATE_TYPES (real_state_type_id),
FOREIGN KEY (admin_id) REFERENCES ADMINS (admin_id)
);

所以 REAL_STATE 的 id 是 REAL_STATE_TYPE，如果我想保持這個表的關系，我怎么能在 java 代碼中 map 到 Z9CE3D1BD8890F16A0C44809359 代碼中。

我的 java 類是：

import javax.persistence.Enumerated;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name= "real_state_types")
public class RealStateType implements Serializable{

    private static final long serialVersionUID = 5442745398170857199L;
    @Id
    @Column(name= "real_state_type_id ")
    private int realStateTypeId;
    @Column(name= "real_state_type")
    @Enumerated(EnumType.STRING)
    private RealStateEnum realStateType;
    @OneToOne(mappedBy = "realStateType", cascade = {CascadeType.ALL})
    private RealState realState;

和：

import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Enumerated;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name = "real_states")
public class RealState {
    @EmbeddedId
    private RealStateID realStateID;
    @Column(name = "real_state_type_id")
    private RealStateType realStateType;
    @ManyToOne
    @JoinColumn(name = "admin_id")
    private Admin admin;
}

Answer 1

為了讓它工作，我相信你需要 1. 刪除

@OneToOne(mappedBy = "realStateType", cascade = {CascadeType.ALL})
private RealState realState;

來自 RealStateType。 2.改變

@Column(name = "real_state_type_id")
private RealStateType realStateType;

進入

@JoinColumn(name = "real_state_type_id")
private RealStateType realStateType;

在真實狀態。

否則，如果可能的話，我會刪除 RealStateType @Entity 並使用

@Enumerated(EnumType.STRING)
@Column(name = "real_state_type", nullable = false)
private RealStateEnum realStateType;

在真實狀態