Java 带有 TopLink 的 JPA：在类路径中找不到 META-INF/persistence.xml
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JPA with TopLink: No META-INF/persistence.xml was found in classpath
提问by Switch
public class LoginTest {
public static void main(String[] args) {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("IRCBotPU");
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
Login lg = new Login();
lg.setPassword("password");
lg.setUserName("Rocky");
em.persist(lg);
em.flush();
Login st = em.find(Login.class, lg.getPassword());
System.out.println(st);
em.getTransaction().commit();
em.close();
emf.close();
}
}
I'm getting an Exception when I try to run this class
当我尝试运行这个类时出现异常
javax.persistence.PersistenceException: No Persistence provider for EntityManager named IRCBotPU:
No META-INF/persistence.xml was found in classpath.
META-INF/persistence.xml is in my classpath. I don't know what is the reason or this exception.
META-INF/persistence.xml 在我的类路径中。我不知道是什么原因或这个例外。
Persistence library is TopLink.
持久性库是 TopLink。
回答by ChssPly76
persistence.xmlshould not be in your classpath; JAR file that contains persistence.xmlin its META-INF folder should.
persistence.xml不应在您的类路径中；包含persistence.xml在其 META-INF 文件夹中的JAR 文件应该。
回答by ChssPly76
Your META-INF/persistence.xml file should look something like this:
您的 META-INF/persistence.xml 文件应如下所示：
// <persistence>
// <persistence-unit name="IRCBotPU">
// <provider>oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider</provider>
// <!-- All persistence classes must be listed -->
// <class>entity.Customer</class>
// <class>entity.Order</class>
// <class>entity.Item</class>
// <properties>
// <!-- Provider-specific connection properties -->
// <property name="toplink.jdbc.driver" value="<database driver>"/>
// <property name="toplink.jdbc.url" value="<database url>"/>
// <property name="toplink.jdbc.user" value="<user>"/>
// <property name="toplink.jdbc.password" value="<password>"/>
// <!-- Provider-specific settings -->
// <property name="toplink.logging.level" value="INFO"/>
// </properties>
// </persistence-unit>
// </persistence>
Your persistence-unit's name attribute in your persistence.xml doesn't match the value you're passing into the Persistence.createEntityManagerFactory method. Make sure that your persistence-unit name is set to "IRCBotPU".
您的persistence.xml 中的persistence-unit 的名称属性与您传递给Persistence.createEntityManagerFactory 方法的值不匹配。确保您的持久性单元名称设置为“IRCBotPU”。
回答by Kelly S. French
The error is somewhat misleading. the XML file itself should notbe in the classpath; the part of the message saying "META-INF/persistence.xml" means that the directory containing META-INF/persistence.xml shouldbe.
这个错误有点误导。XML文件本身应该不会在类路径; 消息中说“META-INF/persistence.xml”的部分意味着包含 META-INF/persistence.xml 的目录应该是。
If your hard drive had the following
如果您的硬盘有以下情况
C:\libs\JPA\META-INF\Persistence.xml
C:\libs\JPA\META-INF\Persistence.xml
then your classpath should include this
那么你的类路径应该包括这个
CLASSPATH=c:\libs\JPA
If META-INF\Persistence.xml were contained in foo.jar, assuming META-INF/Persistence.xml were located on the root folder of the jar, your classpath should have this
如果 META-INF\Persistence.xml 包含在 foo.jar 中，假设 META-INF/Persistence.xml 位于 jar 的根文件夹中，您的类路径应该有这个
CLASSPATH=C:\<path to jar>\foo.jar
This may seem obvious or redundant but my goal is to make sure we're comparing apples to apples and the CLASSPATH, along with classloading, can be a bugger to deal with.
这可能看起来很明显或多余，但我的目标是确保我们将苹果与苹果进行比较，并且 CLASSPATH 以及类加载可能是一个需要处理的问题。
So, can you post your CLASSPATH?
那么，您可以发布您的 CLASSPATH 吗？
回答by marcosbeirigo
I had the same problem, i was keeping my persistence.xml file in the WebContent/META-INF directory, while the jpa specification says:
the root of the persistence unit is the WEB-INF/classes directory; the persistence.xml file is therefore contained in the WEB-INF/classes/META-INF directory
try placing persistence.xml under src/META-INF.
我遇到了同样的问题，我将我的 persistence.xml 文件保存在 WebContent/META-INF 目录中，而 jpa 规范说：
持久性单元的根目录是 WEB-INF/classes 目录；因此，persistence.xml 文件包含在 WEB-INF/classes/META-INF 目录中，
尝试将 persistence.xml 放在 src/META-INF 下。
回答by nu1silva
i have a web application and the following worked fine. What i did was add the META-INF directory with the persistence.xml into the src/main/resources location [Maven project]
我有一个网络应用程序，以下工作正常。我所做的是将带有 persistence.xml 的 META-INF 目录添加到 src/main/resources 位置 [Maven 项目]
回答by Wai Hein
I created a folder callled META-INF under src and it works. "marcosbeirigo" answered it already. I do not know why I have to put that persistance.xml in there though. I put it under WebContent/META-INF and did not work
我在 src 下创建了一个名为 META-INF 的文件夹，它可以工作。“marcosbeirigo”已经回答了。我不知道为什么我必须把那个 persistance.xml 放在那里。我把它放在 WebContent/META-INF 下并没有工作
回答by Aniruddha Das
if you are using IntelliJor a maven project structure you need to place the entire "META-INF/persistence.xml"file in the in resources(src/resources) folder so that it will move your persistence.xmlfile into "WEB-INF/classes/persistence.xml"location.
如果您正在使用IntelliJMaven 项目结构，您需要将整个"META-INF/persistence.xml"文件放在资源（src/resources）文件夹中，以便它将您的persistence.xml文件移动到"WEB-INF/classes/persistence.xml"位置。
if you are using eclipseor something else makes the changes accordingly so that it will move the file to WEB-INF/classes/persistence.xml
如果您正在使用eclipse或其他东西进行相应的更改，以便它将文件移动到WEB-INF/classes/persistence.xml
anything else did not work for me.
其他任何东西都不适合我。
