java - 使用 OpenJPA 和 postgresql 简单创建数据库

Question

我认为我的 TomEE 版本有一些问题，但一旦它运行良好......当我尝试创建数据库时出现问题...这是堆栈:

objc[1068]: Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Home/bin/java and /Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Home/jre/lib/libinstrument.dylib. One of the two will be used. Which one is undefined.
424  unisocial-database  INFO   [main] openjpa.Runtime - OpenJPA dynamically loaded the class enhancer. Any classes that were not enhanced at build time will be enhanced when they are loaded by the JVM.
522  unisocial-database  INFO   [main] openjpa.Runtime - OpenJPA dynamically loaded a validation provider.
537  unisocial-database  INFO   [main] openjpa.Runtime - Starting OpenJPA 2.4.0-nonfinal-1598334
Exception in thread "main" <openjpa-2.4.0-nonfinal-1598334-r422266:1599166    
fatal user error> org.apache.openjpa.persistence.ArgumentException: 
The persistence provider is attempting to use properties 
in the persistence.xml file to resolve the data source. 
A Java Database Connectivity (JDBC) driver or data source class
name must be specified in the openjpa.ConnectionDriverName or 
javax.persistence.jdbc.driver property. The following properties
are available in the configuration:  
"org.apache.openjpa.jdbc.conf.JDBCConfigurationImpl@80992065".

    at org.apache.openjpa.jdbc.schema.DataSourceFactory.newDataSource(DataSourceFactory.java:72)
    at org.apache.openjpa.jdbc.conf.JDBCConfigurationImpl.createConnectionFactory(JDBCConfigurationImpl.java:849)
    at org.apache.openjpa.jdbc.conf.JDBCConfigurationImpl.getDBDictionaryInstance(JDBCConfigurationImpl.java:602)
    at org.apache.openjpa.jdbc.meta.MappingRepository.endConfiguration(MappingRepository.java:1518)
    at org.apache.openjpa.lib.conf.Configurations.configureInstance(Configurations.java:535)
    at org.apache.openjpa.lib.conf.Configurations.configureInstance(Configurations.java:460)
    at org.apache.openjpa.lib.conf.PluginValue.instantiate(PluginValue.java:121)
    at org.apache.openjpa.conf.MetaDataRepositoryValue.instantiate(MetaDataRepositoryValue.java:68)
    at org.apache.openjpa.lib.conf.ObjectValue.instantiate(ObjectValue.java:83)
    at org.apache.openjpa.conf.OpenJPAConfigurationImpl.newMetaDataRepositoryInstance(OpenJPAConfigurationImpl.java:967)
    at org.apache.openjpa.conf.OpenJPAConfigurationImpl.getMetaDataRepositoryInstance(OpenJPAConfigurationImpl.java:958)
    at org.apache.openjpa.kernel.AbstractBrokerFactory.makeReadOnly(AbstractBrokerFactory.java:642)
    at org.apache.openjpa.kernel.AbstractBrokerFactory.newBroker(AbstractBrokerFactory.java:202)
    at org.apache.openjpa.kernel.DelegatingBrokerFactory.newBroker(DelegatingBrokerFactory.java:155)
    at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:226)
    at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:153)
    at org.apache.openjpa.persistence.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:59)
    at eu.algoritmi.unisocial.model.MainP.main(MainP.java:14)

这是我的 persistence.xml:

<?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="unisocial-database"
        transaction-type="JTA">

        <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
        <jta-data-source>unisocial database</jta-data-source>
        <class>eu.algoritmi.unisocial.model.UtenteNonGiuridico</class>
        <class>eu.algoritmi.unisocial.model.Corso</class>
        <class>eu.algoritmi.unisocial.model.Facolta</class>
        <class>eu.algoritmi.unisocial.model.Universita</class>
        <class>eu.algoritmi.unisocial.model.Studente</class>
        <class>eu.algoritmi.unisocial.model.UtenteNonGiuridico</class>

        <properties>
            <property name="openjpa.jdbc.SynchronizeMappings"
                value="buildSchema(SchemaAction=add,ForeignKeys=true)" />
            <property name="openjpa.Log"
                value="DefaultLevel=WARN, Runtime=INFO, Tool=INFO, SQL=TRACE" />
            <property name="openjpa.jdbc.MappingDefaults"
                value="ForeignKeyDeleteAction=restrict,JoinForeignKeyDeleteAction=restrict" />
            <property name="openjpa.RuntimeUnenhancedClasses" value="supported" />

            <property name="javax.persistence.schema-generation.database.action"
                value="drop-and-create" />
            <property
                name="javax.persistence.schema-generation.create-database-schemas"
                value="true" />
        </properties>

    </persistence-unit>
</persistence>

这是resouces.xml

<tomee>
    <Resource id="unisocial database" type="DataSource">
        JdbcDriver          org.postgresql.Driver
        JdbcUrl             jdbc:postgresql://localhost/unisocial
        UserName            unisocial
        Password            unisocial
        JtaManaged          true
        DefaultAutoCommit   false
    </Resource>
</tomee>

这是用来演示效果的主类。

package eu.algoritmi.unisocial.model;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

public class MainP {

    public static void main(String[] args) {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("unisocial-database");
        EntityManager em = emf.createEntityManager();

        Universita u=new Universita("romaTre", null);

        EntityTransaction tx = em.getTransaction();
        tx.begin();
        em.persist(u);
        tx.commit();

        em.close();
        emf.close();
    }       
}

Answer 1

问题与堆栈跟踪中的这条消息有关:

A Java Database Connectivity (JDBC) driver or data source class name must be specified in the openjpa.ConnectionDriverName or javax.persistence.jdbc.driver property.

检查您提供的 persistence.xml 我们可以看到，您忘记提供这两个属性之一。两者之一是必需的，因此您的 TomEE 环境可以确定在连接到 PostgreSQL 后端时要使用哪个 JDBC 驱动程序。 persistence.xml配置如下应该可以解决您的问题:

<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="unisocial-database"
        transaction-type="JTA">
        <provider>org.apache.openjpa.persistence.PersistenceProviderImpl</provider>
        <jta-data-source>unisocial database</jta-data-source>
        <class>eu.algoritmi.unisocial.model.UtenteNonGiuridico</class>
        <class>eu.algoritmi.unisocial.model.Corso</class>
        <class>eu.algoritmi.unisocial.model.Facolta</class>
        <class>eu.algoritmi.unisocial.model.Universita</class>
        <class>eu.algoritmi.unisocial.model.Studente</class>
        <class>eu.algoritmi.unisocial.model.UtenteNonGiuridico</class>

        <properties>

            <!-- Generic JPA configuration attributes -->
            <property name="javax.persistence.jdbc.driver"
                value="org.postgresql.Driver" />
            <property name="javax.persistence.schema-generation.database.action"
                value="drop-and-create" />
            <property name="javax.persistence.schema-generation.create-database-schemas"
                value="true" />

            <!-- OpenJPA specific configuration attributes -->
            <property name="openjpa.jdbc.SynchronizeMappings"
                value="buildSchema(SchemaAction=add,ForeignKeys=true)" />
            <property name="openjpa.Log"
                value="DefaultLevel=WARN, Runtime=INFO, Tool=INFO, SQL=TRACE" />
            <property name="openjpa.jdbc.MappingDefaults"
                value="ForeignKeyDeleteAction=restrict,JoinForeignKeyDeleteAction=restrict" />
            <property name="openjpa.RuntimeUnenhancedClasses" value="supported" />

        </properties>

    </persistence-unit>
</persistence>

请记住将 PostgreSQL 驱动程序的最新 JAR 文件复制到 TomEE 安装的 lib 目录中。通过这种方式，可以在容器中部署的不同 Web 应用程序中找到驱动程序。

希望对您有所帮助。