美好的一天。我嘗試使用持久性api來實現多對多的依賴關係。 我填補新的用戶數據,並嘗試將其添加到數據庫中,但得到的異常:Java持久性api:類在關係屬性中使用非實體類作爲目標實體
Exception Description: [class main.java.entities.User] uses a non-entity [class main.java.entities.UserAccounts] as target entity in the relationship attribute [field accounts].
我嘗試使用@ManyToMany註釋差值在name
部分如bank_user_accounts
和userAccounts
。第二個值是persistence.xml
中的單位名稱。但是這個麻煩依然存在。
用戶類:
@Entity(name="bank_users")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@ManyToMany
@JoinTable(
name = "bank_user_accounts",
joinColumns = @JoinColumn(name = "user_id"),
inverseJoinColumns = @JoinColumn(name = "account_id")
)
private List<UserAccounts> accounts;
}
UserAccounts類:
@Entity(name="bank_user_accounts")
public class UserAccounts {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
@Column(name = "user_id")
private int userId;
@Column(name = "account_id")
private int accountId;
}
的persistence.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
<persistence-unit name="users" transaction-type="RESOURCE_LOCAL">
<class>main.java.entities.User</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="javax.persistence.jdbc.url" value="deleted" />
<property name="javax.persistence.jdbc.user" value="deleted" />
<property name="javax.persistence.jdbc.password" value="deleted" />
</properties>
</persistence-unit>
<persistence-unit name="userAccounts" transaction-type="RESOURCE_LOCAL">
<class>main.java.entities.UserAccounts</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
<property name="javax.persistence.jdbc.url" value="deleted" />
<property name="javax.persistence.jdbc.user" value="deleted" />
<property name="javax.persistence.jdbc.password" value="deleted" />
</properties>
</persistence-unit>
</persistence>
所以,我用這個爲例,現在所有的偉大工程https://www.mkyong.com/hibernate/hibernate-many-to-many-relationship-示例註釋/ – Evgeniy175