3

I would like to use EclipseLink as my JPA engine. We are using a subclass of java.sql.Connection and I would like to know if I can force EclipseLink to use my connection. I would like to set the connection object programmatically.

Something like

MyConnection conn = new MyConnection(JDBC_URL, USR, PWD);
EntityManagerFactory factory = Persistence.createEntityManagerFactory(conn);
4

2 回答 2

1

您可以使用以下代码以编程方式设置自定义连接：

Map properties = new HashMap();

// Configure the internal EclipseLink connection pool
properties.put(JDBC_DRIVER, "oracle.jdbc.OracleDriver");
properties.put(JDBC_URL, "jdbc:oracle:thin:@localhost:1521:ORCL");
properties.put(JDBC_USER, "user-name");
properties.put(JDBC_PASSWORD, "password");
Persistence.createEntityManagerFactory("unit-name", properties);

经过快速谷歌搜索后，我在这里找到了这个答案：

http://eclipse.1072660.n5.nabble.com/Defining-persistence-xml-programatically-td2536.html

我不相信有一种方法可以强制 Eclipselink 仅使用它进行连接java.sql.Connection；至少不是开箱即用。您可以创建一个简单的实用程序方法来传递所述连接并构建一个属性映射，如上所述。

public Map convertConnectionToProperties(Connection conn) {
    // Do the mapping

    return theMap;
}

如果您查看此链接，您会看到

持久性.java

createEntityManagerFactory(String persistenceUnitName) 
createEntityManagerFactory(String persistenceUnitName, Map properties)

这就是它可以作为参数的全部。简单的说; 如果不获取您的连接对象并对其进行调整以返回符合createEntityManagerFactory可以接受的内容，那么您所要求的根本是不可能的。

class MyConnection {
     // Your code here
    
    public Map convertToMap() {
        // Do the mapping

        return theMap;
    }

    public String getPersistenceUnitName() {
        return "Some-Name";
    }
}

然后像这样使用它：

MyConnection conn = new MyConnection(JDBC_URL, USR, PWD);
EntityManagerFactory factory = Persistence.createEntityManagerFactory(conn.getPersistenceUnitName(), conn.convertToMap());
于 2014-06-27T13:13:28.547 回答
0

* 此解决方案使用 Spring Framework。

javax.sql.DataSource

首先，您需要将连接包装在 a 中javax.sql.DataSource，例如：

import java.sql.Connection;
import java.sql.SQLException;

import org.springframework.jdbc.datasource.AbstractDataSource;

public class MyDataSource extends AbstractDataSource {

    private static final String JDBC_URL = "jdbc:mysql://localhost/test";
    private static final String USR = "root";
    private static final String PWD = "";

    public Connection getConnection() throws SQLException {
        return new MyConnection(JDBC_URL, USR, PWD);
    }

    public Connection getConnection(String username, String password)
            throws SQLException {
        return new MyConnection(JDBC_URL, USR, PWD);
    }
}

为避免覆盖所有方法，您可以扩展 Spring 中的现有类。

javax.persistence.EntityManagerFactory

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;

import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.EclipseLinkJpaVendorAdapter;

public class Main {

    public static void main(String[] args) {
        LocalContainerEntityManagerFactoryBean bean =
                new LocalContainerEntityManagerFactoryBean();
        bean.setDataSource(new MyDataSource());
        bean.setPersistenceUnitName("TestPU");
        bean.setJpaVendorAdapter(new EclipseLinkJpaVendorAdapter());
        bean.afterPropertiesSet();

        EntityManagerFactory factory = bean.getNativeEntityManagerFactory();
        EntityManager em = factory.createEntityManager();
        em.getTransaction().begin();
        User user = new User();
        user.setFullname("Mister");
        em.persist(user);
        em.getTransaction().commit();
        em.close();
    }

}

笔记

  • 您可能需要在您的中添加下一个属性persistence.xml：

    <property name="eclipselink.weaving" value="false"/>

  • 我使用了一个独立的 Maven 项目来测试代码和依赖项，pom.xml如下所示：

    <dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.31</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.0.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>4.0.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.eclipse.persistence</groupId>
        <artifactId>eclipselink</artifactId>
        <version>2.5.1</version>
    </dependency>
</dependencies>

    或者，如果您愿意，所需的罐子：

    mysql-connector-java-5.1.31.jar
spring-context-4.0.5.RELEASE.jar
spring-aop-4.0.5.RELEASE.jar
aopalliance-1.0.jar
spring-beans-4.0.5.RELEASE.jar
spring-core-4.0.5.RELEASE.jar
commons-logging-1.1.3.jar
spring-expression-4.0.5.RELEASE.jar
spring-orm-4.0.5.RELEASE.jar
spring-jdbc-4.0.5.RELEASE.jar
spring-tx-4.0.5.RELEASE.jar
eclipselink-2.5.1.jar
javax.persistence-2.1.0.jar
commonj.sdo-2.1.1.jar
于 2014-06-27T14:25:02.420 回答