Java org.hibernate.MappingException：未知实体：annotations.Users
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org.hibernate.MappingException: Unknown entity: annotations.Users
提问by JAN
Consider the hierarchy :
考虑层次结构：
And the following classes and xml :
以及以下类和 xml ：
HibernateUtil.java
HibernateUtil.java
package annotations;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
/**
*
* @author X3
*
*/
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static final String HIBERNATE_CFG = "hibernateAnnotations.cfg.xml";
private static SessionFactory buildSessionFactory()
{
Configuration cfg = new Configuration().addResource(HIBERNATE_CFG).configure();
ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().
applySettings(cfg.getProperties()).buildServiceRegistry();
SessionFactory sessionFactory = cfg.buildSessionFactory(serviceRegistry);
return sessionFactory;
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
Users.java
用户.java
package annotations;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import java.sql.Timestamp;
@Entity
@Table(name = "Users")
public class Users {
@Id
@GeneratedValue
@Column(name = "USER_ID")
private long userID;
@Column(name = "USERNAME", nullable = false, length = 100)
private String username;
@Column(name = "MessageTimeDate", nullable = false)
private java.sql.Timestamp datetime;
@Column(name = "UserMessage", nullable = false)
private String message;
public Users(String username , String message)
{
java.util.Date date = new java.util.Date();
this.datetime = new Timestamp(date.getTime());
this.username = username;
this.message = message;
}
public long getUserID() {
return userID;
}
public void setUserID(long userID) {
this.userID = userID;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public java.sql.Timestamp getDatetime() {
return datetime;
}
public void setDatetime(java.sql.Timestamp datetime) {
this.datetime = datetime;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
Main.java
主程序
package annotations;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
public class Main {
public static void main(String[] args) {
try
{
SessionFactory sf = HibernateUtil.getSessionFactory();
Session session = sf.openSession();
session.beginTransaction();
Users user1 = new Users("Hyman" , "Hello");
session.save(user1);
session.getTransaction().commit();
session.close();
}
catch (Exception e)
{
System.out.println(e.toString());
e.getStackTrace();
}
}
}
And hibernateAnnotations.cfg.xml
和hibernateAnnotations.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/CHAT_DB</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>
<property name="connection.pool_size">1</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="current_session_context_class">thread</property>
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="show_sql">true</property>
<property name="hbm2ddl.auto">create</property>
<mapping class="annotations.Users"></mapping>
</session-factory>
</hibernate-configuration>
When I run main(), the following error appears in output window :
当我运行 main() 时，输出窗口中出现以下错误：
org.hibernate.MappingException: Unknown entity: annotations.Users
But the entity Usersis in annotationspackage , so what's wrong ?
但是实体Users在annotationspackage 中，有什么问题？
采纳答案by Asif Bhutto
The Hibernate configuration file must define the entity classes:
Hibernate 配置文件必须定义实体类：
<mapping class="annotations.Users"/>
Or you must explicitly add the class to the configuration using
或者您必须使用显式将类添加到配置中
configuration.addClass(annotations.Users.class)
// Read mappings as a application resourceName
// addResource is for add hbml.xml files in case of declarative approach
configuration.addResource("myFile.hbm.xml"); // not hibernateAnnotations.cfg.xml
回答by user2247545
Add the following to your xml:
将以下内容添加到您的 xml：
<bean id="sessionFactory"
class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="packagesToScan">
<list>
<value>annotations</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
<tx:annotation-driven transaction-manager="transactionManager" />
<bean id="transactionManager"
class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory" ref="sessionFactory" />
</bean>
回答by Marvo
For those using Spring's Java configuration classes, you might write the following:
对于那些使用 Spring 的 Java 配置类的人，您可以编写以下内容：
@Autowired
@Bean(name = "sessionFactory")
public SessionFactory getSessionFactory(DataSource dataSource) {
LocalSessionFactoryBuilder sessionBuilder = new LocalSessionFactoryBuilder(dataSource);
sessionBuilder.addProperties(getHibernateProperties());
sessionBuilder.addAnnotatedClasses(Foo.class);
sessionBuilder.addAnnotatedClasses(Bar.class);
sessionBuilder.addAnnotatedClasses(Bat.class);
return sessionBuilder.buildSessionFactory();
}
回答by user2148060
Define the Entityclass in Hibernate.cfg.xml
Entity在Hibernate.cfg.xml 中定义类
<mapping class="com.supernt.Department"/>
While creating the sessionFactoryobject Load the Configurationfile Like
在创建sessionFactory对象时加载配置文件
SessionFactory factory = new AnnotationConfiguration().configure("hibernate.cfg.xml").buildSessionFactory();
回答by user5728489
When I was trying to rewrite my example (from tutorialspoint) to use annotations, I got the same exception. This helped me (addAnnotatedClass()):
当我尝试重写我的示例（来自tutorialspoint）以使用注释时，我遇到了同样的异常。这对我有帮助（addAnnotatedClass()）：
Configuration cfg=new Configuration();
cfg.addAnnotatedClass(com.tutorialspoint.hibernate.entity.Employee.class);
cfg.configure();
回答by Shobhit Srivastava
I was having same problem.
我遇到了同样的问题。
Use @javax.persistence.Entityinstead of org.hibernate.annotations.Entity
使用@javax.persistence.Entity代替org.hibernate.annotations.Entity
回答by Ishaq
Problem occurs because of the entry mapping class="annotations.Users"in hibernate.cfg.xmlremove that line then it will be work.
由于删除该行中的条目mapping class="annotations.Users"而出现问题hibernate.cfg.xml，然后它将起作用。
I had the same issue. When I removed the above line then it was working fine for me.
我遇到过同样的问题。当我删除上面的行时，它对我来说工作正常。
回答by Narendra Rawat
Instead of using HibernateUtil.java, to create sessionfactory object, you should use this:
而不是使用 HibernateUtil.java 来创建 sessionfactory 对象，你应该使用这个：
SessionFactory sessionFactory=new AnnotationConfiguration().configure().buildSessionFactory();
Because in order to avoid the exception, you'll have to declare the class object in HibernateUtil.java file as configuration.addAnnotatedClass(Student_Info.class);which looks dumb because we have provided the entry already in hibernate.cfg.xml file.
因为为了避免异常，您必须在 HibernateUtil.java 文件中声明类对象，configuration.addAnnotatedClass(Student_Info.class);因为我们已经在 hibernate.cfg.xml 文件中提供了该条目。
To use the AnnotationConfiguration class you'll have to add a jar to your project build path: http://www.java2s.com/Code/Jar/h/Downloadhibernate353jar.htm
要使用 AnnotationConfiguration 类，您必须在项目构建路径中添加一个 jar：http: //www.java2s.com/Code/Jar/h/Downloadhibernate353jar.htm
回答by Mithun Debnath
public static void main(String[] args) {
try{
// factory = new Configuration().configure().buildSessionFactory();
factory = new AnnotationConfiguration().
configure().
//addPackage("com.xyz") //add package if used.
addAnnotatedClass(Employee.class).
buildSessionFactory();
}catch (Throwable ex) {
System.err.println("Failed to create sessionFactory object." + ex);
throw new ExceptionInInitializerError(ex);
}//you can write like this in your test class inside main method.this way you will be able to do the things using annotaions only
回答by Sandy
Add the following code to hibernate.cfg.xml
将以下代码添加到 hibernate.cfg.xml
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.timeout">300</property>
<property name="hibernate.c3p0.max_statements">50</property>
<property name="hibernate.c3p0.idle_test_period">3000</property>
