起因

　　專案中帶有Entity註解類很多,但實際使用的只有一小部分,每次啟動都需要驗證實體與表結構,拖慢啟動速度

解決方案

　　常用的自己可控的Entity類放在一個包下,走以前spring boot Jpa 邏輯,採用掃描包獲取,外部不可控Entity進行改造配置

1. 啟動類註解掃表包修改

   @EnableJpaRepositories("XXXXXXX")
   @EntityScan("XXXXXX")

2. 繼承LocalContainerEntityManagerFactoryBean類,覆蓋determinePersistenceUnitInfo 方法 並在方法中新增自己需要新增的Entity類

   public
    
    class MyLocalContainerEntityManagerFactoryBean extends LocalContainerEntityManagerFactoryBean {
   
       @Override
       protected PersistenceUnitInfo determinePersistenceUnitInfo(PersistenceUnitManager persistenceUnitManager) {
           PersistenceUnitInfo persistenceUnitInfo = super.determinePersistenceUnitInfo(persistenceUnitManager);
           List
    
   <String> managedClassNames = persistenceUnitInfo.getManagedClassNames();
           managedClassNames.add("com.test.domain.User");
           return persistenceUnitInfo;
       }
   }

3. 新增配置類代替原有LocalContainerEntityManagerFactoryBean

@Configuration
public class MyHibernateJpaAutoConfiguration extends
 
 HibernateJpaAutoConfiguration {

    public MyHibernateJpaAutoConfiguration(DataSource dataSource, JpaProperties jpaProperties, 
　　　　　　ObjectProvider<JtaTransactionManager> jtaTransactionManager, 
　　　　　　ObjectProvider<TransactionManagerCustomizers> transactionManagerCustomizers) {
        super(dataSource, jpaProperties, jtaTransactionManager, transactionManagerCustomizers);
    }


    @Bean
    @Primary
    public LocalContainerEntityManagerFactoryBean entityManagerFactory( 
            JpaVendorAdapter jpaVendorAdapter,
            ObjectProvider<PersistenceUnitManager> persistenceUnitManager) {
        Map<String, Object> vendorProperties = getVendorProperties();
        customizeVendorProperties(vendorProperties);

        MyLocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new MyLocalContainerEntityManagerFactoryBean();

        if (persistenceUnitManager.getIfAvailable() != null) {
            entityManagerFactoryBean.setPersistenceUnitManager(persistenceUnitManager.getIfAvailable());
        }

        entityManagerFactoryBean.setJpaVendorAdapter(jpaVendorAdapter);

        if (isJta()) {
            entityManagerFactoryBean.setJtaDataSource(super.getDataSource());
        } else {
            entityManagerFactoryBean.setDataSource(super.getDataSource());
        }
        entityManagerFactoryBean.setPackagesToScan(super.getPackagesToScan());
        entityManagerFactoryBean.getJpaPropertyMap()
                .putAll(super.getProperties().getProperties());
        entityManagerFactoryBean.getJpaPropertyMap().putAll(vendorProperties);
        return entityManagerFactoryBean;
    }
}