Java &引用;EntityManager没有持久性提供程序“;错误
我是JPA的新手,我试着从书中做一个简单的例子。 但无论我做什么,我都会收到以下错误:Java &引用;EntityManager没有持久性提供程序“;错误,java,jpa,maven,Java,Jpa,Maven,我是JPA的新手,我试着从书中做一个简单的例子。 但无论我做什么,我都会收到以下错误: Exception in thread "main" javax.persistence.PersistenceException: No Persistence provider for EntityManager named EmployeeService at javax.persistence.Persistence.createEntityManagerFactory(Persist
Exception in thread "main" javax.persistence.PersistenceException: No Persistence provider for EntityManager named EmployeeService
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:89)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:60)
at com.mycompany.simpleentity.EmployeeTest.main(EmployeeTest.java:18)
我在谷歌上搜索了很多,我做了所有我读到的关于JPA的事情以下是我的项目的目录树:
.
|-- pom.xml
`-- src
|-- main
| |-- java
| | `-- com
| | `-- mycompany
| | `-- simpleentity
| | |-- Employee.java
| | |-- EmployeeService.java
| | `-- EmployeeTest.java
| `-- resources
| `-- META-INF
| `-- persistence.xml
`-- test
以下是我的pom.xml:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany</groupId>
<artifactId>SimpleEntity</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>SimpleEntity</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.persistence</groupId>
<artifactId>persistence-api</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>9.0-801.jdbc4</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>com.mycompany.simpleentity.EmployeeTest</mainClass>
<!-- <classpathLayoutType>repository</classpathLayoutType> -->
<classpathMavenRepositoryLayout>true</classpathMavenRepositoryLayout>
<classpathPrefix>${env.HOME}/.m2/repository</classpathPrefix>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>
</project>
这是我的persistence.xml
<persistence 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_1_0.xsd"
version="1.0">
<persistence-unit name="EmployeeService" transaction-type="RESOURCE_LOCAL">
<class>com.mycompany.simpleentity.Employee</class>
<properties>
<property name="toplink.jdbc.driver"
value="org.postgresql.Driver"/>
<property name="toplink.jdbc.url"
value="jdbc:postgresql://localhost:5432/testdb;create=true"/>
<property name="toplink.jdbc.user" value="postgres"/>
<property name="toplink.jdbc.password" value="111"/>
</properties>
</persistence-unit>
</persistence>
com.mycompany.simplentity.Employee
我做错了什么?
事先谢谢你。实际上
您似乎并不依赖于实际的Perience提供程序
JPA本身没有实现,您还需要使用Hibernate/Toplink/OpenJPA作为实际解决方案。根据persistence.xml,您使用Toplink和PostgreSQL作为RDBMS。当您在pom.xml中引用PostgreSQL JDBC驱动程序时,您没有将TopLink声明为依赖项
我猜想(我承认)持久性API在类路径中找不到TopLink(您的持久性提供者)。尝试将TopLink添加为依赖项。JPA是由多个JPA提供商(Hibernate、EclipseLink、OpenJPA、TopLink)实现的规范 您需要选择要使用的提供程序,并向
pom.xml
添加适当的依赖项。您还需要在persistence.xml
中指定您的提供者
例如,如果您使用OpenJPA(我在本例中选择了它,因为它的最新版本在Maven Central Repo中可用,因此无需配置特定于供应商的存储库):
朱尼特
朱尼特
3.8.1
试验
org.apache.openjpa
openjpa all
2.0.1
postgresql
postgresql
9.0-801.jdbc4
org.apache.openjpa.persistence.PersistenceProviderImpl
com.mycompany.simplentity.Employee
如果您使用JPA+eclipselink提供程序,请不要使用此代码
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost/Database name" />
<property name="javax.persistence.jdbc.user" value="" />
<property name="javax.persistence.jdbc.password" value="" />
<property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver" />
</properties>
1)确保已定义持久性提供程序(针对任何提供程序):
openjpa的Ex:
org.apache.openjpa.persistence.PersistenceProviderImpl
...
...
2) 如果您使用的是自定义构建/编译过程(maven等)
确保将Meta INF/persistence.xml复制到compiled/classes文件夹。JPA作为一个规范有多个提供者(实现者)。您必须选择一个为JPA规范提供实际字节码的字节码。Hibernate是常见的选择,但您的选择可能不同。一旦您确定了它,将其作为依赖项添加到POM中。否则,将JAR文件添加到构建路径中
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<!-- Note that you don't need persistence-api dependency - it's transitive -->
<dependency>
<groupId>org.apache.openjpa</groupId>
<artifactId>openjpa-all</artifactId>
<version>2.0.1</version>
</dependency>
<dependency>
<groupId>postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>9.0-801.jdbc4</version>
</dependency>
</dependencies>
<persistence 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_1_0.xsd"
version="1.0">
<persistence-unit name="EmployeeService" transaction-type="RESOURCE_LOCAL">
<!-- Provider specification -->
<provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
<class>com.mycompany.simpleentity.Employee</class>
<properties>
<property name="javax.persistence.jdbc.driver"
value="org.postgresql.Driver"/>
<property name="javax.persistence.jdbc.url"
value="jdbc:postgresql://localhost:5432/testdb;create=true"/>
<property name="javax.persistence.jdbc.user" value="postgres"/>
<property name="javax.persistence.jdbc.password" value="111"/>
</properties>
</persistence-unit>
</persistence>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost/Database name" />
<property name="javax.persistence.jdbc.user" value="" />
<property name="javax.persistence.jdbc.password" value="" />
<property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver" />
</properties>