Java org.hibernate.MappingException:未知实体：annotations.Users

考虑层次结构：

以及以下类和xml：

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;
    }
}

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;
    }

}

Users.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;
    }
}

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

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("Jack" , "Hello");
               session.save(user1);
               session.getTransaction().commit();
               session.close();
        }

        catch (Exception e)
        {
            System.out.println(e.toString());
            e.getStackTrace();
        }


    }
}

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>

---

但是实体

Users

在

annotations

包中，那么怎么了

Hibernate配置文件必须定义实体类：

<mapping class="annotations.Users"/>

---

将以下内容添加到xml中：

<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>

注释
org.hibernate.dialogue.mysqldialogue
真的

对于使用Spring Java配置类的用户，您可以编写以下代码：

@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();
}

---

在Hibernate.cfg.xml中定义

实体

类

  <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>

---

当我试图重写我的示例（从tutorialspoint）以使用注释时，我遇到了相同的异常。这对我有帮助（addAnnotatedClass（））：

---

我也有同样的问题

---

使用

@javax.persistence.Entity

而不是

org.hibernate.annotations.Entity

出现问题，因为

hibernate.cfg.xml

中的条目

mapping class=“annotations.Users”

删除该行即可

---

我也有同样的问题。当我删除上述行时，它对我来说工作正常。

要创建sessionfactory对象，您应该使用以下命令，而不是使用HibernateUtil.java：

SessionFactory sessionFactory=new AnnotationConfiguration().configure().buildSessionFactory();

因为为了避免异常，您必须将HibernateUtil.java文件中的class对象声明为

configuration.addAnnotatedClass（Student\u Info.class）

看起来很愚蠢，因为我们已经在hibernate.cfg.xml文件中提供了条目

要使用AnnotationConfiguration类，必须将jar添加到项目构建路径：

---

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>

5
20
300
50
3000

如果您的实体是通过注释映射的，请将以下代码添加到您的配置中

configuration.addAnnotatedClass(theEntityPackage.EntityClassName.class);

比如,

configuration.addAnnotatedClass(com.foo.foo1.Products.class);

如果实体映射为xml文件，请使用addClass而不是addAnnotatedClass

例如,

configuration.addClass(com.foo.foo1.Products.class);

---

如果需要更多帮助，请点击我。

我也遇到了同样的问题，我搜索了将近2个小时，并尝试了不同的可能方法，如更换旧的hibernate JAR和更改DB表模式。但最终得到的解决方案如下：

SessionFactory factory = new Configuration().configure().buildSessionFactory(); //This line to be replaced with below commented line

将上述内容替换为

//Configuration config = new Configuration().configure();
//ServiceRegistry servReg = new StandardServiceRegistryBuilder().applySettings(config.getProperties()).build();
//SessionFactory factory = config.buildSessionFactory(servReg);

---

然后它会很好地工作。

我遇到了类似的问题并添加了

 sessionFactory.setAnnotatedClasses(User.class);

这句话有帮助，但在此之前，我有

sessionFactory.setPackagesToScan(new String[] { "com.rg.spring.model" });

我不知道为什么那个不起作用。用户类在com.rg.spring.model下

---

请告诉我如何通过packagesToScan方法使其工作。

检查dispatcher-servlet.xml中的属性packagesToScan中是否给出了包名

<bean id="sessionFactory"             class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">  
        <property name="dataSource" ref="dataSource" />  
        <property name="packagesToScan" value="**entity package name here**"></property> 
        <property name="hibernateProperties">  
            <props>  
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>  
                <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>  
            </props>  
        </property>  
    </bean>

${hibernate.dial}
${hibernate.show_sql}

如果您能够承受外部依赖，请使用EntityScanner。它将无缝地注入您的所有实体类，即使来自多个包。只需在配置设置后添加以下行

Configuration configuration = new Configuration().configure();    
EntityScanner.scanPackages("com.fz.epms.db.model.entity").addTo(configuration);
// And following depencency if you are using Maven
<dependency>
        <groupId>com.github.v-ladynev</groupId>
        <artifactId>fluent-hibernate-core</artifactId>
        <version>0.3.1</version>
</dependency>

Configuration配置=新配置（）.configure（）；
EntityScanner.scanPackages（“com.fz.epms.db.model.entity”）.addTo（配置）；
//如果您使用的是Maven，请遵循依赖关系
com.github.v-ladynev
流畅的休眠内核
0.3.1

---

通过这种方式，您不需要在hibernate映射文件中声明所有实体。

我发现接受的答案对解决代码中遇到的异常没有帮助。虽然在技术上不正确，但我也不满意其他人关于引入冗余的建议：

• 使用

  configuration.addAnnotatedClass（…）

• 在

  hibernate\u test.cfg.xml

  中创建一个

  hbm.xml

  文件和资源映射，这些文件和映射对现有注释是多余的
• 使用原始问题中未提及的外部依赖项扫描（已映射）类存在的包

然而，我发现了两种可能的解决方案，我想与大家分享，这两种解决方案都独立地解决了我在自己的代码中遇到的异常。

我与@ron使用了相同的

MappingException

（使用了一个几乎相同的

HibernateUtil

类）：

在我的

hibernate\u test.cfg.xml

配置文件中，我有所需的类映射：

<mapping class="myPackage.Device"/>

两种可能的解决方案：

首先，我使用的是Hibernate 5.2，对于那些使用Hibernate 5的人来说，使用

元数据

对象来构建

会话工厂

应该是可行的。它似乎也是当前推荐的：

Second，而

Configuration

是，@ron没有说他使用的是哪个版本的Hibernate，所以这个解决方案对某些人来说也可能有价值

在实例化和配置

Configuration

和

ServiceRegistry

对象时，我发现操作顺序发生了非常微妙的变化，从而使我自己的代码与众不同。

原始订单（

Configuration

在

ServiceRegistry

之前创建和配置）：

新订单（

ServiceRegistry

在

Configuration

之前创建和配置）：

冒着TLDR的风险，我还要指出，关于

hibernate\u test.cfg.xml

，我的测试表明

configuration.getProperties（）

方法只返回

元素，而

元素被排除在外。这与for

配置中术语“属性”和“映射”的具体用法一致。我会让步的
<bean id="sessionFactory"             class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">  
        <property name="dataSource" ref="dataSource" />  
        <property name="packagesToScan" value="**entity package name here**"></property> 
        <property name="hibernateProperties">  
            <props>  
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>  
                <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>  
            </props>  
        </property>  
    </bean>

Configuration configuration = new Configuration().configure();    
EntityScanner.scanPackages("com.fz.epms.db.model.entity").addTo(configuration);
// And following depencency if you are using Maven
<dependency>
        <groupId>com.github.v-ladynev</groupId>
        <artifactId>fluent-hibernate-core</artifactId>
        <version>0.3.1</version>
</dependency>

public final class HibernateUtil {

    private static SessionFactory sessionFactory = null;
    private static ServiceRegistry serviceRegistry = null;

    private HibernateUtil() {}

    public static synchronized SessionFactory getSessionFactory() {
        if ( sessionFactory == null ) {
            Configuration configuration = new Configuration().configure("hibernate_test.cfg.xml");
            serviceRegistry = new StandardServiceRegistryBuilder()
                    .applySettings(configuration.getProperties())
                    .build();
            sessionFactory = configuration.buildSessionFactory( serviceRegistry );
        }
        return sessionFactory;
    }
// exception handling and closeSessionFactory() omitted for brevity
}

<mapping class="myPackage.Device"/>

package myPackage.core;
import javax.persistence.*;

@Entity
@Table( name = "devices" )
public class Device {
    //body omitted for brevity
}

public static synchronized SessionFactory getSessionFactory() {
    if ( sessionFactory == null ) {

        // exception handling omitted for brevity

        serviceRegistry = new StandardServiceRegistryBuilder()
                .configure("hibernate_test.cfg.xml")
                .build();

        sessionFactory = new MetadataSources( serviceRegistry )
                    .buildMetadata()
                    .buildSessionFactory();
    }
    return sessionFactory;
}

public static synchronized SessionFactory getSessionFactory() {
    if ( sessionFactory == null ) {

        // exception handling omitted for brevity

        Configuration configuration = new Configuration().configure("hibernate_test.cfg.xml");

        serviceRegistry = new StandardServiceRegistryBuilder()
                .applySettings( configuration.getProperties() )
                .build();

        sessionFactory = configuration.buildSessionFactory( serviceRegistry );
    }
    return sessionFactory;
}

public static synchronized SessionFactory getSessionFactory() {
    if ( sessionFactory == null ) {

        // exception handling omitted for brevity

        serviceRegistry = new StandardServiceRegistryBuilder()
                .configure("hibernate_test.cfg.xml")
                .build();

        sessionFactory = new Configuration().buildSessionFactory( serviceRegistry );
    }
    return sessionFactory;
}

private static SessionFactory buildSessionFactory() {
    try {           
        StandardServiceRegistry standardRegistry = new StandardServiceRegistryBuilder()
            .configure( "hibernate.cfg.xml" )
            .build();

        Metadata metadata = new MetadataSources( standardRegistry )
            .getMetadataBuilder()
            .build();

        return metadata.getSessionFactoryBuilder().build();
    } catch(...) {
        ...
    }
}

MetadataSources metadataSources = new MetadataSources(serviceRegistry);
Metadata metadata = metadataSources.getMetadataBuilder().build();
SessionFactory sessionFactory= metadata.getSessionFactoryBuilder().build();

 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.Transaction;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
 import org.hibernate.cfg.Configuration;
 import org.hibernate.cfg.Environment;
 import org.hibernate.service.ServiceRegistry;

    Configuration configuration = new Configuration();
    configuration.setProperty("hibernate.current_session_context_class", "thread");
    configuration.setProperty(Environment.DRIVER, "org.postgresql.Driver");
    configuration.setProperty(Environment.URL, lmsParams.getDbProperties().getDbURL());
    configuration.setProperty(Environment.USER, lmsParams.getDbProperties().getUsername());
    configuration.setProperty(Environment.PASS, lmsParams.getDbProperties().getPassword());

    configuration.setProperty("hibernate.connection.release_mode", "auto");
    configuration.setProperty("hibernate.dialect", "org.hibernate.dialect.PostgreSQLDialect");
    configuration.setProperty("hibernate.show_sql", "true");
    configuration.setProperty(Environment.HBM2DDL_AUTO, "create");
    configuration.addAnnotatedClass(LMSSourceTable.class);
    ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
            .applySettings(configuration.getProperties())
            .build();
    SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);

<dependency>
<groupId>org.reflections</groupId>
<artifactId>reflections</artifactId>
<version>0.9.11</version>
</dependency>

 MetadataSources metadataSources = new 
 MetadataSources(serviceRegistry);
 Reflections entityPackageReflections = new Reflections("com.company.abc.package.name");
    entityPackageReflections.getTypesAnnotatedWith(Entity.class).forEach(metadataSources::addAnnotatedClass);
    Metadata metadata = metadataSources.getMetadataBuilder().build();
    SessionFactory sessionFactory=  metadata.getSessionFactoryBuilder().build();

<!--  Configu Hibernate session factory -->
    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
        <property name="dataSource" ref="myDataSource" />
        <property name="packagesToScan" value="SCANN_YOUR_PACKAGE.controller.entity" />
        <property name="hibernateProperties">
           <props>
              <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
              <prop key="hibernate.show_sql">true</prop>
           </props>
        </property>
   </bean>