如何使用JPA / Hibernate自动注册实体：未知实体 [英] How to auto-register entities with JPA/Hibernate: Unknown entity
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问题描述
我很难忍受一个Hibernate / JPA配置问题，它阻止了我的JPA注释实体被自动注册： java.lang.IllegalArgumentException：未知实体：com.example.crm.server.model.Language
at org.hibernate.ejb.AbstractEntityManagerImpl.persist（AbstractEntityManagerImpl.java:671）
at com.example。 crm.server.model.Language.persist（Language.java:64）
at com.example.crm.server.LanguageTest.testPersistAndRemove（LanguageTest.java:32）
at sun.reflect.NativeMethodAccessorImpl。 invoke0（Native Method）
at sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:39）
at sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:25）
$ b在我的实体类中，我有：
@Table（name =Languages）
public class语言实现Serializable
{
@Id
private L ong id;
私人字符串名称;
// etc ...
}
而在MySQL中，语言表看起来像：
+ ------------- + ------- --- + ------ + ----- + --------- + ------- +
|字段|类型|空| Key |默认|额外|
+ ------------- + ---------- + ------ + ----- + ------- - + ------- +
| Language_ID | int（11）| NO | PRI | NULL | |
|名称| char（18）|是| | NULL | |
+ ------------- + ---------- + ------ + ----- + ------- - + ------- +
2行（0.00秒）
<<？xml version =1.0encoding =UTF-8 ？>
< 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_1_0.xsd
version = 1.0 >
< persistence-unit name =crm>
< provider> org.hibernate.ejb.HibernatePersistence< / provider>
<属性>
< property name =hibernate.dialectvalue =org.hibernate.dialect.MySQLDialect/>
< property name =hibernate.connection.driver_classvalue =com.mysql.jdbc.Driver/>
< property name =hibernate.connection.urlvalue =jdbc：mysql：// localhost / crm/>
< property name =hibernate.connection.usernamevalue =crmuser/>
< property name =hibernate.connection.passwordvalue =mypass/>
< property name =hibernate.c3p0.min_sizevalue =5/>
< property name =hibernate.c3p0.max_sizevalue =20/>
< property name =hibernate.c3p0.idleTestPeriodvalue =30/>
< property name =hibernate.c3p0.timeoutvalue =0/>
< property name =hibernate.c3p0.max_statementsvalue =0/>
< property name =hibernate.format_sqlvalue =true/>
< property name =hibernate.query.jpaql_strict_compliancevalue =false/>
< property name =hibernate.validator.apply_to_ddlvalue =false/>
< property name =hibernate.validator.autoregister_listenersvalue =false/>
< property name =hibernate.archive.autodetectionvalue =class，hbm/>
< property name =hibernate.hbm2ddl.autovalue =create/>
< / properties>
< / persistence-unit>
< /持久性>
编辑：以下是我得到我的EntityManager并坚持：
public void persist（）
{
EntityManager em = entityManager（） ;
尝试
{
em.getTransaction（）。begin（）;
em.persist（this）;
em.getTransaction（）。commit（）;
}
finally
{
em.close（）;
public static EntityManager entityManager（）
{
return EMF.get（）。createEntityManager（）;
}
解决方案<结果很简单：直接在persistence.xml文件中列出类。 armandino和MikelRascher都引导我回答这个问题，尽管间接地给了他们这个答案。
这是我现在使用的persistence.xml：
<？xml version =1.0encoding =UTF-8？>
< 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_1_0.xsd
version = 1.0 >
< persistence-unit name =crm>
< provider> org.hibernate.ejb.HibernatePersistence< / provider>
< class> com.example.Language< / class>
<属性>
< property name =hibernate.dialectvalue =org.hibernate.dialect.MySQLDialect/>
< property name =hibernate.connection.driver_classvalue =com.mysql.jdbc.Driver/>
< property name =hibernate.connection.urlvalue =jdbc：mysql：// localhost / crm/>
< property name =hibernate.connection.usernamevalue =myuser/>
< property name =hibernate.connection.passwordvalue =mypass/>
< property name =hibernate.c3p0.min_sizevalue =5/>
< property name =hibernate.c3p0.max_sizevalue =20/>
< property name =hibernate.c3p0.idleTestPeriodvalue =30/>
< property name =hibernate.c3p0.timeoutvalue =0/>
< property name =hibernate.c3p0.max_statementsvalue =0/>
<！ - property name =hibernate.show_sqlvalue =true/> - >
< property name =hibernate.format_sqlvalue =true/>
< property name =hibernate.query.jpaql_strict_compliancevalue =false/>
< property name =hibernate.validator.apply_to_ddlvalue =false/>
< property name =hibernate.validator.autoregister_listenersvalue =false/>
< property name =hibernate.archive.autodetectionvalue =class，hbm/>
< property name =hibernate.hbm2ddl.autovalue =create/>
< / properties>
< / persistence-unit>
< /持久性>
I'm stumped with a Hibernate/JPA configuration issue that's preventing my JPA-annotated entities from being automatically registered:
java.lang.IllegalArgumentException: Unknown entity: com.example.crm.server.model.Language at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:671) at com.example.crm.server.model.Language.persist(Language.java:64) at com.example.crm.server.LanguageTest.testPersistAndRemove(LanguageTest.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)In my entity class I have:
@Entity @Table(name="Languages") public class Language implements Serializable { @Id private Long id; private String name; // etc... }And in MySQL, the Languages table looks like:
+-------------+----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+----------+------+-----+---------+-------+ | Language_ID | int(11) | NO | PRI | NULL | | | Name | char(18) | YES | | NULL | | +-------------+----------+------+-----+---------+-------+ 2 rows in set (0.00 sec)And my persistence.xml looks like:
<?xml version="1.0" encoding="UTF-8"?> <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_1_0.xsd" version="1.0"> <persistence-unit name="crm"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/> <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/> <property name="hibernate.connection.url" value="jdbc:mysql://localhost/crm"/> <property name="hibernate.connection.username" value="crmuser"/> <property name="hibernate.connection.password" value="mypass"/> <property name="hibernate.c3p0.min_size" value="5"/> <property name="hibernate.c3p0.max_size" value="20"/> <property name="hibernate.c3p0.idleTestPeriod" value="30"/> <property name="hibernate.c3p0.timeout" value="0"/> <property name="hibernate.c3p0.max_statements" value="0"/> <property name="hibernate.format_sql" value="true"/> <property name="hibernate.query.jpaql_strict_compliance" value="false"/> <property name="hibernate.validator.apply_to_ddl" value="false"/> <property name="hibernate.validator.autoregister_listeners" value="false"/> <property name="hibernate.archive.autodetection" value="class, hbm"/> <property name="hibernate.hbm2ddl.auto" value="create"/> </properties> </persistence-unit> </persistence>EDIT: here's how I'm getting my EntityManager and persisting:
public void persist() { EntityManager em = entityManager(); try { em.getTransaction().begin(); em.persist(this); em.getTransaction().commit(); } finally { em.close(); } } public static EntityManager entityManager() { return EMF.get().createEntityManager(); }
解决方案It turned out to be fairly simple: list the classes directly in the persistence.xml file. Both armandino and MikelRascher led me to this answer, though indirectly, so props to them.
Here is the persistence.xml I'm using now:
<?xml version="1.0" encoding="UTF-8"?> <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_1_0.xsd" version="1.0"> <persistence-unit name="crm"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <class>com.example.Language</class> <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/> <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/> <property name="hibernate.connection.url" value="jdbc:mysql://localhost/crm"/> <property name="hibernate.connection.username" value="myuser"/> <property name="hibernate.connection.password" value="mypass"/> <property name="hibernate.c3p0.min_size" value="5"/> <property name="hibernate.c3p0.max_size" value="20"/> <property name="hibernate.c3p0.idleTestPeriod" value="30"/> <property name="hibernate.c3p0.timeout" value="0"/> <property name="hibernate.c3p0.max_statements" value="0"/> <!--property name="hibernate.show_sql" value="true"/>--> <property name="hibernate.format_sql" value="true"/> <property name="hibernate.query.jpaql_strict_compliance" value="false"/> <property name="hibernate.validator.apply_to_ddl" value="false"/> <property name="hibernate.validator.autoregister_listeners" value="false"/> <property name="hibernate.archive.autodetection" value="class, hbm"/> <property name="hibernate.hbm2ddl.auto" value="create"/> </properties> </persistence-unit> </persistence>
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