Java 使用OpenJPA和postgresql简单地创建数据库

我想我的版本有点问题，但一旦它工作得这么好。。。。 当我尝试创建数据库时，出现了一些错误。。。 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)

---

该问题与stacktrace中的此消息有关：

Java数据库连接（JDBC）驱动程序或数据源类 必须在

openjpa.ConnectionDriverName

中指定名称，或

javax.persistence.jdbc.driver

属性

检查您提供的

persistence.xml

我们可以看到，您忘记提供这两个属性中的一个。两者之一都是必需的，因此您的TomEE环境可以确定在连接到PostgreSQL后端时使用哪个JDBC驱动程序。按以下方式配置的

persistence.xml

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>

org.apache.openjpa.persistence.PersistenceProviderImpl
统一数据库
eu.algoritmi.unisocial.model.Utentenengiuridico
eu.algoritmi.unisocial.model.Corso
eu.algoritmi.unisocial.model.Facolta
eu.algoritmi.unisocial.model.Universita
eu.algoritmi.unisocial.model.Studente
eu.algoritmi.unisocial.model.Utentenengiuridico

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。这样，就可以在容器中部署的不同web应用程序中找到驱动程序

希望能有帮助

<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>

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();
    }       
}

<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>