图解一级缓存：
代码：
@Test
public void firstCache(){
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
Session session = sessionFactory.openSession();
Transaction trans = session.beginTransaction();
Book book1 = (Book) session.get(Book.class, 1);
System.out.println(book1);
Book book2 = (Book) session.get(Book.class, 1);
System.out.println(book2);
trans.commit();
session.close();
sessionFactory.close();
}
debug进行调试查看，如下图：