浅析Java模板方法的一种使用方式

SessionFactory sessionFactory = (SessionFactory) applicationContext.getBean("sessionFactory");
Session session = sessionFactory.openSession();
try {
    session.beginTransaction();
    String sql = "update table set A = :a where id = :id";
    session.createNativeQuery(sql)
            .setParameter("a", "a")
            .setParameter("id", id)
            .executeUpdate();
    session.getTransaction().commit();
} catch (Exception e) {
    session.getTransaction().rollback();
} finally {
    session.close();
}

public abstract class TransactionManagerTemplate {

    
    public void handle() {}

    
    public void exceptionHandle() {}

    
    public void finallyHandle() {}

}

@Component
public class TransactionManager {

    @Autowired
    private ApplicationContext applicationContext;

    
    public static final String DEFAULT_SESSION_FACTORY = "sessionFactory";


    
    public void runTransaction(Session session, TransactionManagerTemplate transactionManagerTemplate) {
        try {
            session.beginTransaction();
            transactionManagerTemplate.handle();
            session.getTransaction().commit();
        } catch (Exception e) {
            transactionManagerTemplate.exceptionHandle();
            session.getTransaction().rollback();
        } finally {
            transactionManagerTemplate.finallyHandle();
            session.close();
        }
    }

    
    public SessionFactory getSessionFactory() {
        return getSessionFactory(DEFAULT_SESSION_FACTORY);
    }

    
    public SessionFactory getSessionFactory(String beanName) {
        SessionFactory sessionFactory = (SessionFactory) applicationContext.getBean(beanName);
        if(sessionFactory == null) {
            throw new BAPException("不存在BeanName为【{}】的SessionFactory", beanName);
        }
        return sessionFactory;
    }

    
    public Session getSession() {
        return getSessionFactory(DEFAULT_SESSION_FACTORY).openSession();
    }

    
    public Session getSession(String sessionFactoryBeanName) {
        return getSessionFactory(sessionFactoryBeanName).openSession();
    }

}

Session session = transactionManager.getSession();
transactionManager.runTransaction(session, new TransactionManagerTemplate() {
    @Override
    public void handle() {
        // try中要添加的业务逻辑
    }

    @Override
    public void exceptionHandle() {
        // catch中要添加的业务逻辑
    }

    @Override
    public void finallyHandle() {
        // finally中要添加的业务逻辑
    }
});