3

我正在尝试添加一个Generator，package-info.java这样我就不必在每个@Entity类的顶部重新编写相同的代码。但是当我尝试运行程序应用程序时，我得到一个错误。

Session Factory could not be created.org.hibernate.AnnotationException: 
Unknown Id.generator: ID_GENERATOR

如果我@GenericGenerator在课堂上名列前茅，@Entity它就可以了。我是否在这里遗漏了一些关键点。

我找到了这个踏板，但是那里发布的答案对我不起作用。

配置

package-info.java

@org.hibernate.annotations.GenericGenerator(
    name = "ID_GENERATOR",
    strategy = "enhanced-sequence",
    parameters = {
        @org.hibernate.annotations.Parameter(
            name = "sequence_name",
            value = "JPA_SEQUENCE"
        ),
        @org.hibernate.annotations.Parameter(
            name = "initial_value",
            value = "1"
        )
    }
)
package com.example.hibernate.model;

Student.java

package com.example.hibernate.model;

@Entity
@Table(name = "student")
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class Student implements Serializable {

    @Id
    @GeneratedValue(generator = "ID_GENERATOR")
    private int id;

    @Column(name = "first_name", nullable = false)
    private String firstName;

    @Column(name = "last_name", nullable = false)
    private String lastName;
}

persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/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">

    <persistence-unit name="persistence" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>


        <class>com.example.hibernate.model.Student</class>
        <properties>
            <property name="hibernate.archive.autodetection" value="class" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
            <property name="hibernate.connection.driver_class" value="org.h2.Driver" />
            <property name="hibernate.connection.url" value="jdbc:h2:mem:test_mem" />
            <property name="hibernate.connection.user" value="sa" />
             <property name="hibernate.show_sql" value="true"/>
            <property name="hibernate.flushMode" value="FLUSH_AUTO" />
            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
        </properties>
    </persistence-unit>
</persistence>
4

2 回答 2

2

您应该在persistence.xml 中简单地添加本身包含GenericGenerator 的包。

这个例子

<class>com.example.hibernate.model</class>
<class>com.example.hibernate.model.Student</class>
于 2017-05-15T21:30:59.793 回答
1

我发现的解决方案之一是@javax.persistence.SequenceGenerator在每个@Entity类上使用

@Entity
@SequenceGenerator(name = "MY_S", sequenceName = "ID_GENERATOR")
public class Student implements Serializable {

    @Id
    @GeneratedValue(generator = "MY_S")
    private int id;

}

这比在每个类上定义要少一点复制和粘贴。GenericGenerator@Entity

我们也可以消除@SequenceGenerator每个类中的使用，但在这种情况下@Entity我们需要使用。XML

创建一个orm.xml并将此文件添加mapping-file为persistence.xml

<mapping-file>META-INF/orm.xml</mapping-file>

在里面orm.xml我们定义sequence-generator

<sequence-generator name="MY_S"
                    sequence-name="ID_GENERATOR"/>
于 2017-02-18T17:55:58.970 回答