java - JPA:从属性创建 EntityManagerFactory

Question

我在 JAR 项目中使用 JPA，并使用 persistence.xml 来设置我的 EntityManager。

但由于 persistence.xml 在构建后位于 JAR 中，因此用户之后更改设置非常复杂。所以我正在寻找一种解决方案，我可以通过在运行时加载的属性文件配置我的连接。

我在网上遇到了这个解决方案:

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);

这是我一直在寻找的解决方案，但我在这里遗漏了一件事:在我的 persistence.xml 中，我还在映射文件上声明了一个架构名称:

持久性.xml:

<persistence version="2.0" ...>
  <persistence-unit name="jpa" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <class>...</class>
    <exclude-unlisted-classes>true</exclude-unlisted-classes>
    <properties>
      <property name="javax.persistence.jdbc.url" value="..."/>
      <property name="javax.persistence.jdbc.password" value="..."/>
      <property name="javax.persistence.jdbc.driver" value="oracle.jdbc.OracleDriver"/>
      <property name="javax.persistence.jdbc.user" value="..."/>
    </properties>
    <mapping-file>META-INF/orm.xml</mapping-file>
  </persistence-unit>
</persistence>

orm.xml:

<entity-mappings ...>
 <persistence-unit-metadata>
  <persistence-unit-defaults>
   <schema>SCHEMA_NAME</schema>
  </persistence-unit-defaults>
 </persistence-unit-metadata>
</entity-mappings>

所以我的问题基本上是:是否有一个属性可用于在运行时设置架构，就像我对其他属性所做的那样？

或者有更好的解决方案吗？

提前致谢!

Answer 1

切换到java配置。然后你可以通过 Autowiring 环境轻松地注入(inject)属性值

这个例子非常基础。但一般来说，如果您知道如何进行 xml 配置，则可以将其直接映射到 Java 配置上

contextConfig.java

/**
 * Spring Context configuration.
 */
@ComponentScan(basePackages = { "com.example" })
@PropertySource({ "classpath:common.properties" })
@Configuration
@Import(JpaConfig.class)
public class ContextConfig extends WebMvcConfigurerAdapter {
    /**
     * This bean is needed because Spring when you use xml config to load property files the bean is automatically
     * created... when you use @PropertySource then not so much
     * @return new bean
     */
    @Bean
    public PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }
}

jpaConfig.java

@Configuration
@EnableJpaRepositories("com.example.repository")
public class JpaConfig {

    @Autowired
    private Environment env;

    /**
     * Create the fooDataSource Bean.
     * @return fooDataSource Bean
     */
    @Bean
    public BasicDataSource fooDataSource() {

        BasicDataSource basicDataSource = new BasicDataSource();
        basicDataSource.setDriverClassName(env.getProperty("cfg_foo.driver.name"));
        basicDataSource.setUrl(env.getProperty("cfg_foo.jdbc.url"));
        basicDataSource.setUsername(env.getProperty("cfg_foo.username"));
        basicDataSource.setPassword(env.getProperty("cfg_foo.password"));
        basicDataSource.setPoolPreparedStatements(Boolean.valueOf(env.getProperty("cfg_foo.poolPreparedStatements")));
        basicDataSource.setInitialSize(Integer.valueOf(env.getProperty("cfg_foo.poolInitialSize")));
        basicDataSource.setMaxActive(Integer.valueOf(env.getProperty("cfg_foo.poolMaxActive")));
        basicDataSource.setMaxIdle(Integer.valueOf(env.getProperty("cfg_foo.poolMaxIdle")));
        basicDataSource.setValidationQuery("SELECT '1'");

        return basicDataSource;
    }

    /**
     * Create the hibernateJpaVendorAdapter Bean.
     * @return hibernateJpaVendorAdapter Bean
     */
    @Bean
    public HibernateJpaVendorAdapter hibernateJpaVendorAdapter() {

        HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        adapter.setDatabasePlatform("org.hibernate.dialect.MySQLDialect");
        adapter.setShowSql(Boolean.valueOf(env.getProperty("show.sql")));
        adapter.setGenerateDdl(Boolean.valueOf(env.getProperty("format.sql")));

        return adapter;
    }

    /**
     * Create the entityManagerFactory Bean.
     * @return entityManagerFactory Bean
     */
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {

        LocalContainerEntityManagerFactoryBean entityManagerFactory = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactory.setPersistenceUnitName("foo");
        entityManagerFactory.setDataSource(fooDataSource());
        entityManagerFactory.setJpaVendorAdapter(hibernateJpaVendorAdapter());
        entityManagerFactory.setPackagesToScan("com.example.repository");

        return entityManagerFactory;
    }

}