持久性文件的正确的家应该是src / main / resources / META-INF。在这个问题中，你提到src / main / resource / META_INF。注意，META-INF中的资源和破折号（ - ）中应该有一个's'，而不是一个下划线。那些只是打错了问题吗？如果没有，修复路径，它应该工作。

I know there are other questions on SO about this issue, but none of the solutions have worked for me. I'm using maven to build a java project in eclipse, and I have my persistence.xml file in the src/main/resource/META_INF folder. But when I try to mvn install, I always get this error:

No Persistence provider for EntityManager named plasma.persistence

Looking through the console output it appears to be caused by this:

[org.hibernate.jpa.boot.internal.PersistenceXmlParser] - HHH000318: Could not find any META-INF/persistence.xml file in the classpath

Here is my persistence.xml file:

<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_2_0.xsd"
    version="2.0">
<persistence-unit name="plasma.persistence" transaction-type="RESOURCE_LOCAL">
    <properties>
        <property name="hibernate.dialect" value="org.hibernate.spatial.dialect.postgis.PostgisDialect"/>
        <property name="hibernate.connection.driver_class" value="org.postgresql.Driver"/>
        <property name="hibernate.connection.url" value="jdbc:postgresql://localhost:5432:xxxxx"/>
        <property name="hibernate.connection.username" value="xxxxx"/>
        <property name="hibernate.connection.password" value="xxxxx"/>
        <property name="hibernate.connection.pool_size" value="5"/>
        <property name="hibernate.show_sql" value="true"/>
        <property name="hibernate.format_sql" value="true"/>
        <property name="hibernate.max_fetch_depth" value="5"/>
        <property name="hibernate.hbm2ddl.auto" value="update"/>
    </properties>
</persistence-unit>

I have tried right clicking on the project and adding the META_INF folder to the build path, and it still doesn't work. Any ideas?

The proper home for the persistence file should be src/main/resources/META-INF. In the question, you mention src/main/resource/META_INF. Note, there should be an 's' in resources and a dash (-) in META-INF, not an underscore. Are those just typos in the question? If not, fix the path and it should work.