来自JavaSE的DBCP（数据库连接池）和JPA

Question

对于JavaSE客户端，如何处理DBCP？使用JDBC，我知道如何添加Apache DBCP。我可以将Apache DBCP添加到JPA吗？如果是这样，怎么样？

persistence.xml文件是否有这个选项？

代码：

package legacy.database; 

import java.util.ArrayList; 
import java.util.List; 
import java.util.logging.Logger; 
import javax.persistence.EntityManager; 
import javax.persistence.EntityManagerFactory; 
import javax.persistence.Persistence; 
import javax.persistence.Query; 
import javax.persistence.criteria.CriteriaBuilder; 
import javax.persistence.criteria.CriteriaQuery; 
import javax.persistence.criteria.Predicate; 
import javax.persistence.criteria.Root; 

public class MyQueries { 

    private static final Logger log = Logger.getLogger(MyQueries.class.getName()); 
    private EntityManagerFactory emf = Persistence.createEntityManagerFactory("LegacyDatabasePU"); 
    private EntityManager em = emf.createEntityManager(); 

    public MyQueries() { 
    } 

    private List<Clients> findAll() { 
     Query q = em.createQuery("select c from Clients c"); 
     List<Clients> clients = q.getResultList(); 
     em.close(); 
     return clients; 
    } 

    public List<Clients> selectByCriteria(Criteria criteria) { 
     CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder(); 
     CriteriaQuery<Clients> clientCriteriaQuery = criteriaBuilder.createQuery(Clients.class); 
     Root<Clients> clientRoot = clientCriteriaQuery.from(Clients.class); 
     clientCriteriaQuery.select(clientRoot); 
     List<Predicate> predicates = new ArrayList<>(); 
     predicates.add(criteriaBuilder.like(clientRoot.get(Clients_.phone1), "%" + criteria.getPhone1() + "%")); 
     if (!criteria.getStatus().equalsIgnoreCase("all")) { 
      predicates.add(criteriaBuilder.like(clientRoot.get(Clients_.status), "%" + criteria.getStatus() + "%")); 
     } 
     clientCriteriaQuery.where(predicates.toArray(new Predicate[0])); 
     List<Clients> clients = em.createQuery(clientCriteriaQuery).getResultList(); 
     em.close(); 
     return clients; 
    } 

    public Clients findById(int id) { 
     Clients client = em.find(Clients.class, id); 
     em.close(); 
     return client; 
    } 

} 

的persistence.xml：

<?xml version="1.0" encoding="UTF-8"?> 
<persistence version="2.1" xmlns="http://xmlns.jcp.org/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="LegacyDatabasePU" transaction-type="RESOURCE_LOCAL"> 
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> 
    <class>legacy.database.Clients</class> 
    <properties> 
     <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/legacy?zeroDateTimeBehavior=convertToNull"/> 
     <property name="javax.persistence.jdbc.password" value="gjkgjtd"/> 
     <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/> 
     <property name="javax.persistence.jdbc.user" value="jdbc"/> 
    </properties> 
    </persistence-unit> 
</persistence> 

我没有使用Tomcat，还是其他容器。

Answer 1

根据您的persistence.xml，您使用连接URL，驱动程序名称和使用的用户名/密码创建一个EntityManagerFactory，这不一定会汇集连接。因此，无法使用Spring将Apache DBCP添加到JPA或其他平台如DataNucleus。如果你使用hibernate，你可以配置hibernate-annotation.cfg.xml喜欢这个，

<hibernate-configuration> 
<session-factory> 
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> 
    <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/myschema</property> 
    <property name="hibernate.connection.username">user</property> 
    <property name="hibernate.connection.password">password</property> 
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property> 
    <property name="show_sql">true</property> 

    <property name="hibernate.dbcp.initialSize">8</property> 
    <property name="hibernate.dbcp.maxActive">20</property> 
    <property name="hibernate.dbcp.maxIdle">20</property> 
    <property name="hibernate.dbcp.minIdle">0</property> 
</session-factory> 
</hibernate-configuration> 

Answer 2

是的，这是可能的。您可以通过代码传递数据源，如this blog post所示。