详解Hibernate注解方式的二级缓存

<property name="cache.use_second_level_cache">true</property>
 <property name="cache.provider_class">net.sf.ehcache.hibernate.EhCacheProvider</property>

@Cache(usage=CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)

//实体类@cacheable 
@Entity @Cacheable 
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE) 
public class Forest { ... } 
 
//集合类@cache 
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER) 
@JoinColumn(name="CUST_ID") 
@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE) 
public SortedSet<Ticket> getTickets() { 
  return tickets; 
} 
 
 

@Test 
  public void testFind() {//Model1是使用了二级缓存的，这里只会发出一条sql语句 
    Session session = factory.openSession(); 
    Model1 model = (Model1)session.get(Model1.class, 1); 
     
    System.out.println(model.getId()); 
    Session session2 = factory.openSession(); 
    Model1 model2 = (Model1)session2.get(Model1.class, 1); 
    System.out.println(model2.getId()); 
     
    session.close(); 
    session2.close(); 
  } 
   
  @Test 
  public void testFind2() {//Model2没有进行二级缓存，所以这里会发出两条sql语句 
    Session session = factory.openSession(); 
    Model2 model = (Model2)session.get(Model2.class, 1); 
     
    System.out.println(model.getId()); 
    Session session2 = factory.openSession(); 
    Model2 model2 = (Model2)session2.get(Model2.class, 1); 
    System.out.println(model2.getId()); 
     
    session.close(); 
    session2.close(); 
  } 

@Test 
  public void testFind4() { 
    //在没有给Model1里面的models加上二级缓存的注解@Cache之前， 
    //不同的Session里面的同一个对象使用models的时候会发出多条sql语句 
    //而加上了@Cache之后，下面只会发出一条SQL语句 
    Session session = factory.openSession(); 
    Model1 model = (Model1)session.get(Model1.class, 1); 
    List<Model2> models = model.getModels(); 
    for (Model2 mode2: models) { 
      System.out.println(mode2.getId()); 
    } 
    Session session2 = factory.openSession(); 
    Model1 model1 = (Model1)session2.get(Model1.class, 1); 
    List<Model2> models2 = model1.getModels(); 
    for (Model2 model2: models2) { 
      System.out.println(model2.getId()); 
    } 
    session.close(); 
    session2.close(); 
  } 

@OneToMany(mappedBy="model1") 
  @Cache(usage=CacheConcurrencyStrategy.READ_ONLY) 
  public List<Model2> getModels() { 
    return models; 
  }