使用JPA单项一对多外键关联-Java开发

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JPA单项一对多外键关联

一对多即一个对象中包含又另外一个对象的集合。

User主表代码

@Table(name="USER")
@Entity
public class User {
    private Integer id;
    private String username;
    private String userpassword;
    private String useraddress;
    private List<Order> listOrder;

    @JoinColumn(name="LIST_ORDER")
    @OneToMany(fetch=FetchType.LAZY,cascade=CascadeType.REMOVE)
    public List<Order> getListOrder() {
        return listOrder;
    }
    public void setListOrder(List<Order> listOrder) {
        this.listOrder = listOrder;
    }
    @Id
    @TableGenerator(name="PK_PRIMARY",
    table="order_user_sque",
    pkColumnName="pk_column_name",
    pkColumnValue="pk_column",
    valueColumnName="pk_column_value",
    allocationSize=1)
    @GeneratedValue(strategy=GenerationType.TABLE,generator="PK_PRIMARY")
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }

    @Column(name="USERNAME")
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }

    @Column(name="USERPASSWORD")
    public String getUserpassword() {
        return userpassword;
    }

    public void setUserpassword(String userpassword) {
        this.userpassword = userpassword;
    }

    @Column(name="USERADDRESS")
    public String getUseraddress() {
        return useraddress;
    }
    public void setUseraddress(String useraddress) {
        this.useraddress = useraddress;
    }
}

代码中：@JoinColumn(name="LIST_ORDER") -> 表示将外键名设置为LIST_ORDER

@OneToMany(fetch=FetchType.LAZY,cascade=CascadeType.REMOVE) -> OneToMany中fetch表示查询时的加载模式[懒加载还是积极加载],cascade属性表示要级联操作的模式，此处为删除主表后从表一并删除。

Order从表代码

@Entity
@Table(name="ORDER_USER")
public class Order {
    private Integer id;
    private String orderName;
    //private User user;

    @Id
    @GeneratedValue
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getOrderName() {
        return orderName;
    }
    public void setOrderName(String orderName) {
        this.orderName = orderName;
    }
}