Question

尝试使用 JPA 和 EJB 开发REST应用时，我遇到了下一个问题。

我在NetBeans中有3个项目（相同的工作区，只是项目，不是EAR或那些奇怪的东西）：

其中一个是Java应用程序，我在其中从数据库创建了一些实体类。在同一个项目中，我创建了包含来自实体的控制器类的其他包。我测试了创建java主类并使用控制器的项目。

另一个项目是一个EJB模块，它就像一个包一样简单，并且是其中的下一个类：

package com.studentejb;
import java.util.List;
import javax.ejb.LocalBean;
import javax.ejb.Stateless;
import studentdao.StudentTO;
import studentdao.StudentJpaController;

@Stateless
@LocalBean
public class StudentEJB {

    private StudentJpaController studentDao = new StudentJpaController();

    public List<StudentTO> findStudents() {
        return studentDao.findStudentTO();
    }
}

如您所见，我导入了之前的JAR项目（具有实体控制器的项目）。我还使用java主类测试了这个EJB项目，并且它可以工作。

最后一个项目是一个Web应用程序，您可以想象我想使用上一个项目的EJB模块，但在尝试输入资源http://localhost:8080/studentWeb/student/时出现以下错误：

12:00:12,384 ERROR [io.undertow.request] (default task-2) UT005023:    Exception handling request to /studentWeb/student/hola:     com.google.common.util.concurrent.ExecutionError:     java.lang.ExceptionInInitializerError
at com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2201)
at com.google.common.cache.LocalCache.get(LocalCache.java:3937)
at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3941)
at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4824)
at org.jboss.weld.util.cache.LoadingCacheUtils.getCacheValue(LoadingCacheUtils.java:49)
.
.
.

at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ExceptionInInitializerError
at studentdao.StudentJpaController.<init>(StudentJpaController.java:40)
at com.studentejb.StudentEJB.<init>(StudentEJB.java:23)
at com.studentweb.Resources.<init>(Resources.java:52)
at com.studentweb.Resources$Proxy$_$$_WeldClientProxy.<init>(Unknown Source)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
.
.
.

... 58 more
Caused by: javax.persistence.PersistenceException: Unable to locate persistence units 
at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:99)
at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:86)
at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:67)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:55)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)
at studentdao.EntityProvider.<clinit>(EntityProvider.java:20)
... 80 more

Caused by: javax.persistence.PersistenceException: Invalid persistence.xml.
Error parsing XML [line : -1, column : -1] : cvc-elt.1.a: Cannot find the     declaration of element 'persistence'.

at org.hibernate.jpa.boot.internal.PersistenceXmlParser.validate(PersistenceXmlParser.java:377)
at org.hibernate.jpa.boot.internal.PersistenceXmlParser.loadUrl(PersistenceXmlParser.java:310)
at org.hibernate.jpa.boot.internal.PersistenceXmlParser.parsePersistenceXml(PersistenceXmlParser.java:114)
at org.hibernate.jpa.boot.internal.PersistenceXmlParser.doResolve(PersistenceXmlParser.java:104)
at org.hibernate.jpa.boot.internal.PersistenceXmlParser.locatePersistenceUnits(PersistenceXmlParser.java:86)
at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:95)
... 85 more

以下是Web应用程序的代码（Resources.java）：

@Path("/student")
public class Resources {
    @EJB
    private StudentEJB studentEjb;

    @Context
    private UriInfo context;

    public Resources() throws FileNotFoundException, IOException, NamingException {
        studentEjb = new StudentEJB();
    }

    @GET
    @Path("/")
    @Produces(MediaType.APPLICATION_JSON)
    public Response getJson() {
        return Response.ok(studentEjb.findStudents()).build();
    }
}

所以我使用2个JAR作为Web项目，一个使用EJB模块，另一个使用实体和控制器..

以下是 JPA 项目生成的persistence.xml：

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://xmlns.jcp.org/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">
  <persistence-unit name="studentJPAPU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <!-- <provider>org.hibernate.ejb.HibernatePersistence</provider> -->
    <class>studentjpa.Address</class>
    <class>studentjpa.Phone</class>
    <class>studentjpa.Student</class>
    <class>studentjpa.Email</class>
    <properties>
      <property name="javax.persistence.jdbc.url" value="jdbc:sqlserver://localhost:1433;databaseName=tca_student_db;integratedSecurity=true"/>
      <property name="javax.persistence.jdbc.user" value="xxxx"/>
      <property name="javax.persistence.jdbc.driver" value="com.microsoft.sqlserver.jdbc.SQLServerDriver"/>
      <property name="javax.persistence.jdbc.password" value="xxxx"/>
    </properties>
  </persistence-unit>
</persistence>

谢谢！

Answer 1

引起：javax.persistence.PersistenceException：无效 persistence.xml中。解析XML时出错[line：-1，column：-1]： cvc-elt.1.a：找不到元素声明＆＃39;持久性＆＃39;。

这里：

<persistence version="2.0" xmlns="http://xmlns.jcp.org/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">

xmlns：http://xmlns.jcp.org/xml/ns/persistence与xsischemaLocation中的命名空间不匹配，即http://java.sun.com/xml/ns/persistence

尝试在两者中使用相同的内容：

<persistence version="2.0" 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">

无法使用Web应用程序中的EJB

1 个答案: