javax.persistence.PersistenceException:无法找到持久性单元

我有一个Maven项目，我把它转换成JPA项目，现在可以与Maven一起使用。我的

persistence.xml

如下所示：

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
    <persistence-unit name="my-pu" transaction-type="RESOURCE_LOCAL">
        <description>My Persistence Unit</description>
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <class>model.entity.Tweet</class>
        <class>model.entity.TweetHashtag</class>
        <class>model.entity.TweetUrl</class>
        <class>model.entity.User</class>
        <exclude-unlisted-classes>true</exclude-unlisted-classes>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
            <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
            <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/tweetDB"/>
            <property name="hibernate.connection.username" value="root"/>
            <property name="hibernate.connection.password" value="root"/>
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/tweetDB"/>
            <property name="javax.persistence.jdbc.user" value="root"/>
            <property name="javax.persistence.jdbc.password" value=""/>
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
        </properties>
    </persistence-unit>
</persistence>

我在构建路径和项目本身的类路径中包括了不同的JAR:

hibernate验证

，

java持久化

，

hibernate jpa

和

hibernate entityManager

。我还在资源文件夹中复制了

persistence.xml

。 我做了很多事情，但都不管用，总是犯同样的错误

---

提前感谢您的建议

能否尝试从xml中删除以下内容

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

---

您应该将持久化单元名称传递给

persistence.createEntityManagerFactory

在您的persistence.xml中显示：

<persistence-unit name="my-pu" transaction-type="RESOURCE_LOCAL"> 

---

在

createEntityManagerFactory

中作为参数给出的名称应该存在于xml文件中的一个持久化元素中。

这看起来像是JPA 2.1版本的xml模式有问题

---

试试看。希望它对您有用。

如果您使用Eclipse，请检查导出窗口“将所需库复制到生成的JAR旁边的子文件夹中”

在由管理的容器（例如嵌入式

Tomcat8x

容器）上运行的webapp中创建

EntityManagerFactory

时，配置Cargo，使其复制

javax。事务：jta

和（隐式）

org.hibernate:hibernate entitymanager

依赖项进入Tomcat的共享类路径，如下所示：

:
:
javax.transaction
jta
${jta.version}
假如
org.hibernate.ogm
hibernate-ogm-neo4j
${hibernate.version}
:
:
:
org.codehaus.cargo
cargo-maven2-plugin
${cargo.version}
:
嵌入的
org.apache.tomcat
雄猫
${tomcat.version}
:
org.hibernate
休眠实体管理器
共享
javax.transaction
jta
共享

现在它说：由以下原因引起：javax.persistence.PersistenceException:Invalid persistence.xml。分析XML时出错[line:-1，column:-1]：cvc elt.1:元素“persistence”中的Deklarition kann nicht gefunden werden.线程“thread-1”中的异常javax.persistence.PersistenceException:无法找到持久性单元tnx现在更好：线程“thread-1”中的异常java.lang.IllegalArgumentException:Unknown entity:javafx.util.Pair位于org.hibernate.jpa.spi.AbstractEntityManagerImpl.persist（AbstractEntityManagerImpl.java:1184）处model.TweetPersistent.insertToDB（TweetPersistent.java:35）处model.TweetPersistent.persist（TweetPersistent.java:24）处controller.TwitterStreamConsumer.run（TwitterStreamConsumer.java:25）在java.lang.Thread.run（Thread.java:745）我不知道什么是

Pair

。

EntityManager

只有在为需要持久化的类定义@Entity注释并且需要在persistence.xml中定义此类时才起作用。否则，您将看到上述异常。

Picked up JAVA_TOOL_OPTIONS: -javaagent:/usr/share/java/jayatanaag.jar 
log4j:WARN No appenders could be found for logger (twitter4j.HttpClientImpl).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Exception in thread "Thread-1" javax.persistence.PersistenceException: Unable to locate persistence units
    at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:101)
    at org.hibernate.jpa.HibernatePersistenceProvider.getEntityManagerFactoryBuilderOrNull(HibernatePersistenceProvider.java:88)
    at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:69)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:79)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:54)
    at model.TweetPersistent.insertToDB(TweetPersistent.java:32)
    at model.TweetPersistent.persist(TweetPersistent.java:24)
    at controller.TwitterStreamConsumer.run(TwitterStreamConsumer.java:25)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javax.persistence.PersistenceException: Invalid persistence.xml.
Error parsing XML [line : -1, column : -1] : cvc-elt.1: Deklaration des Elements "persistence" kann nicht gefunden werden.
    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:97)
    ... 8 more

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

<persistence-unit name="my-pu" transaction-type="RESOURCE_LOCAL"> 

Persistence.createEntityManagerFactory("my-pu");

<project ...>
    :
    <dependencies>
        :
        <dependency>
            <groupId>javax.transaction</groupId>
            <artifactId>jta</artifactId>
            <version>${jta.version}</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.hibernate.ogm</groupId>
            <artifactId>hibernate-ogm-neo4j</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
    </dependencies>
    :
    <build>
        :
        <plugins>
            :
            <plugin>
                <groupId>org.codehaus.cargo</groupId>
                <artifactId>cargo-maven2-plugin</artifactId>
                <version>${cargo.version}</version>
                <configuration>
                    :
                    <container>
                        <type>embedded</type> 
                        <artifactInstaller>
                            <groupId>org.apache.tomcat</groupId>
                            <artifactId>tomcat</artifactId>
                            <version>${tomcat.version}</version>
                        </artifactInstaller>
                        :
                        <dependencies>
                            <dependency>
                                <groupId>org.hibernate</groupId>
                                <artifactId>hibernate-entitymanager</artifactId>
                                <classpath>shared</classpath>
                            </dependency>
                            <dependency>
                                <groupId>javax.transaction</groupId>
                                <artifactId>jta</artifactId>
                                <classpath>shared</classpath>
                            </dependency>
                        </dependencies>
                    </container>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>