ClassNotFound : 创建实体管理器工厂时的 javax.persistence.Persistence

Posted 2023-04-18

【中文标题】ClassNotFound : 创建实体管理器工厂时的 javax.persistence.Persistence

【英文标题】：ClassNotFound : javax.persistence.Persistence when creating entity Manager Factory

【发布时间】：2015-07-16 23:01:42

【问题描述】：

我正在使用 JSF 和 hibernate 开发一个项目。

我将项目分为3层（视图、服务、DAO）

在服务层我正在创建一个 DAO 类的实例， 但是当到达 Persistence.createEntityManagerFactory("E_GYM") 它会引发异常，请参见下面的块

public abstract class BaseDao<T> implements Serializable 
    private static final long serialVersionUID = 1L;

    //the next line is #18
    private static final EntityManagerFactory emf = Persistence.createEntityManagerFactory("E_GYM");

//....

public class TechniqueService implements Serializable 
    private static final long serialVersionUID = -853877188695729368L;

    private TechniqueDao techniqueDao = new TechniqueDao();

    public TechniqueService() 
    //CRUD service methods...

这里是 Persistence.xml 文件：

<?xml version="1.0" encoding="UTF-8"?>

http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">

<persistence-unit name="E_GYM" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>

    <properties>
        <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
       <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/e_gym" />

        <property name="javax.persistence.jdbc.user" value="root" />
        <property name="javax.persistence.jdbc.password" value="root" />
        <property name="hibernate.show_sql" value="true" />

        <property name="hibernate.connection.shutdown" value="true" />
        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />

    </properties>
</persistence-unit>

但面临这个例外：

java.lang.ClassNotFoundException: javax.persistence.Persistence
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
at nassar.apps.orm.dao.BaseDao.<clinit>(BaseDao.java:18)
at nassar.apps.gym.services.TechniqueService.<init>(TechniqueService.java:12)
at nassar.apps.gym.views.TechniquesView.getTechniqueService(TechniquesView.java:90)
at nassar.apps.gym.views.TechniquesView.fillTechniques(TechniquesView.java:41)
at nassar.apps.gym.views.TechniquesView.<init>(TechniquesView.java:26)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:186)
at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:100)
at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:409)
at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:269)
at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:244)
at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:116)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:71)
at org.apache.el.parser.AstValue.getValue(AstValue.java:160)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UIData.getValue(UIData.java:732)
at org.primefaces.component.datatable.DataTable.getValue(DataTable.java:1002)
at org.primefaces.component.api.UIData.getDataModel(UIData.java:629)
at javax.faces.component.UIData.getRowCount(UIData.java:356)
at org.primefaces.component.api.UIData.calculateFirst(UIData.java:175)
at org.primefaces.component.datatable.DataTableRenderer.preRender(DataTableRenderer.java:110)
at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:82)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:924)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1863)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:894)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1856)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1859)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:443)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

任何帮助将不胜感激...

【参考方案1】：

谢谢各位。 我发现了错误。 我在 lib 内的一个文件夹中将 hibernate jar 分组，如下所示。

WebContent/WEB-INF/lib/hibernate-2/[所有需要的jar列表]，如下

所以直接在 lib 文件夹下移动罐子解决了这个问题。 或者我认为将 hibernate 文件夹从项目属性添加到 Deployment Assemply 也可以解决问题。