未找到类[org.apache.derby.jdbc.ClientDriver].尝试连接到db时

Question

我在Netbeans中建立了一个项目,创建了一个脚本,用javadb建立了一个新的数据库.我可以通过gui连接到它 - 显示表内容等,但当我运行一个应用程序时:

 EntityManager em = Persistence.createEntityManagerFactory("lab5PU").createEntityManager();

我得到这个很长的例外:

[EL Info]: 2013-04-05 21:40:45.554--ServerSession(1198260109)--EclipseLink, version: Eclipse Persistence Services - 2.3.0.v20110604-r9504
[EL Severe]: 2013-04-05 21:40:45.574--ServerSession(1198260109)--Local Exception Stack: 
Exception [EclipseLink-4003] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException
Exception in thread "AWT-EventQueue-0" javax.persistence.PersistenceException: Exception [EclipseLink-4003] (Eclipse Persistence Services - 2.3.0.v20110604-r9504): org.eclipse.persistence.exceptions.DatabaseException
Exception Description: Configuration error.  Class [org.apache.derby.jdbc.ClientDriver] not found.
Exception Description: Configuration error.  Class [org.apache.derby.jdbc.ClientDriver] not found.
    at org.eclipse.persistence.exceptions.DatabaseException.configurationErrorClassNotFound(DatabaseException.java:82)

我可以在服务的驱动程序部分看到javadb驱动程序,所以我不知道错误是什么.

编辑:persistance.xml按要求:

<?xml version="1.0" encoding="UTF-8"?>
<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">
  <persistence-unit name="lab5PU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <class>lab5.Colleagues</class>
    <properties>
      <property name="javax.persistence.jdbc.url" value="jdbc:derby://localhost:1527/lab5"/>
      <property name="javax.persistence.jdbc.password" value="mypass"/>
      <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.ClientDriver"/>
      <property name="javax.persistence.jdbc.user" value="admin"/>
      <property name="eclipselink.ddl-generation" value="create-tables"/>
    </properties>
  </persistence-unit>
</persistence>

Answer 1

我认为你遇到的问题是你没有在项目的类路径中使用Derby驱动程序.

您可以轻松实现将JavaDB库添加到项目中:

• 右键单击该项目
• 属性 - >库
• 添加库 - > JavaDB驱动程序

这包括derby.jar,derbyclient.jar并derbynet.jar在项目的类路径中.

该derbyclient.jar包含类org.apache.derby.jdbc.ClientDriver代码抱怨.