在spring boot中指定自定义持久性单元

Question

我在Spring启动应用程序中有以下配置：

@Bean(name="entityManagerFactory")
public LocalContainerEntityManagerFactoryBean entityManagerFactory( 
            @Value("${ds.fake.driverClass}") String driverClass,
            @Value("${ds.fake.url}") String url,
            @Value("${ds.fake.user}") String user,
            @Value("${ds.fake.password}") String password,
            @Value("${ds.fake.hibernateDialect}") String hibernateDialect){

        LocalContainerEntityManagerFactoryBean bean = new LocalContainerEntityManagerFactoryBean();
//      bean.setPersistenceUnitName("fake");
        bean.setPersistenceProviderClass(HibernatePersistenceProvider.class);
        bean.setPersistenceUnitManager(persistenceUnitManager(driverClass,url,user,password));
        bean.setJpaVendorAdapter(adapter());
        bean.setJpaProperties((Properties)fakeJpaProperties(hibernateDialect).get());
        bean.setDataSource(fakeDataSource(driverClass,url,user,password));
        //bean.setPackagesToScan("my.required.package");
        bean.afterPropertiesSet();
        return bean;   
    }
    @Bean
    public MergingPersistenceUnitManager persistenceUnitManager(
            @Value("${ds.fake.driverClass}") String driverClass,
            @Value("${ds.fake.url}") String url,
            @Value("${ds.fake.user}") String user,
            @Value("${ds.fake.password}") String password){
        MergingPersistenceUnitManager merger = new MergingPersistenceUnitManager();
//      merger.setPersistenceXmlLocations("classpath*:META-INF/fake/persistence.xml");
        merger.setPackagesToScan("my.required.package");
//      merger.setDefaultDataSource(fakeDataSource(driverClass,url,user,password));
        return merger;
    }

    @Bean
    public HibernateJpaVendorAdapter adapter(){
        HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
        adapter.setGenerateDdl(false);
        return adapter;
    }

    @Bean(initMethod="init",destroyMethod="close")
    public static PoolingDataSource fakeDataSource(
            @Value("${ds.fake.driverClass}") String driverClass,
            @Value("${ds.fake.url}") String url,
            @Value("${ds.fake.user}") String user,
            @Value("${ds.fake.password}") String password) {
        PoolingDataSource bean = new PoolingDataSource();
        bean.setClassName("bitronix.tm.resource.jdbc.lrc.LrcXADataSource");
        bean.setUniqueName("fakeDataSource");
        bean.setMinPoolSize(2);
        bean.setMaxPoolSize(10);
        bean.setMaxIdleTime(900);
        bean.setUseTmJoin(true);
        bean.setDeferConnectionRelease(true);
        bean.setAutomaticEnlistingEnabled(true);
        bean.setAllowLocalTransactions(true);
        bean.setIsolationLevel("READ_COMMITTED");
        Properties props = new Properties();
        props.setProperty("driverClassName", driverClass);
        props.setProperty("url", url);
        props.setProperty("user", user);
        props.setProperty("password", password);
        bean.setDriverProperties(props);
        return bean;
    }

如果我启动我的应用程序，我收到以下错误：

Caused by: java.lang.IllegalStateException: Persistence unit with name 'default' already obtained
        at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.obtainPersistenceUnitInfo(DefaultPersistenceUnitManager.java:678)
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.determinePersistenceUnitInfo(LocalContainerEntityManagerFactoryBean.java:355)
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:307)
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:318)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1613)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1550)
        ... 21 more

但是，如果我尝试取消注释行bean.setPersistenceUnitName("fake");，我会收到新错误：

Caused by: java.lang.IllegalArgumentException: No persistence unit with name 'fake' found
        at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.obtainPersistenceUnitInfo(DefaultPersistenceUnitManager.java:674)
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.determinePersistenceUnitInfo(LocalContainerEntityManagerFactoryBean.java:355)
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:307)
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:318)
        at com.ixaris.providers.fake.app.boot.FakeAppBooter.entityManagerFactory(FakeAppBooter.java:226)
        at com.ixaris.providers.fake.app.boot.FakeAppBooter$$EnhancerBySpringCGLIB$$6ec884df.CGLIB$entityManagerFactory$2(<generated>)
        at com.ixaris.providers.fake.app.boot.FakeAppBooter$$EnhancerBySpringCGLIB$$6ec884df$$FastClassBySpringCGLIB$$cefb3e29.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228)
        at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:312)
        at com.ixaris.providers.fake.app.boot.FakeAppBooter$$EnhancerBySpringCGLIB$$6ec884df.entityManagerFactory(<generated>)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:166)
        ... 24 more

我怎样才能解决这个问题？或者自己“创建”持久性单元？