設置休眠第二級緩存

Question

我是新的休眠和春季，我試驗休眠二級緩存。但它似乎不起作用。我有以下測試類：

@RunWith(SpringJUnit4ClassRunner.class) 
@ContextConfiguration(locations = { "classpath:applicationContext.xml" }) 
@TransactionConfiguration 
@Transactional 
public class CacheTest extends AbstractTransactionalJUnit4SpringContextTests 
{ 
    @Test 
     public void testCache1() 
     { 
     System.out.println("Running testCache1"); 
     ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); 
     MutableDAO<AppUser> appUserDAO = new MutableDAOImpl<AppUser>(AppUser.class, (SessionFactory) ctx.getBean("OnMediaSessionFactory"), 10); 
     assertNotNull("AppUser DAO is null.", appUserDAO); 

     SessionFactory sessionFactory = (SessionFactory)ctx.getBean("OnMediaSessionFactory"); 
     long numberOfUsers = appUserDAO.countAll(); 

     System.out.println("Number of rows :" + numberOfUsers); 
     final String cacheRegion = AppUser.class.getCanonicalName(); 

     SecondLevelCacheStatistics settingsStatistics = sessionFactory.getStatistics(). 
      getSecondLevelCacheStatistics(cacheRegion); 
     StopWatch stopWatch = new StopWatch(); 
     stopWatch.start(); 
     appUserDAO.findAll(); 
     stopWatch.stop(); 
     System.out.println("Query time : " + stopWatch.getTotalTimeSeconds()); 
     System.out.println(settingsStatistics); 
    } 

    @Test 
    public void testCache2() 
    { 
     System.out.println("Running testCache2"); 
     ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); 
     MutableDAO<AppUser> appUserDAO = new MutableDAOImpl<AppUser>(AppUser.class, (SessionFactory) ctx.getBean("OnMediaSessionFactory"), 10); 
     assertNotNull("AppUser DAO is null.", appUserDAO); 

     SessionFactory sessionFactory = (SessionFactory)ctx.getBean("OnMediaSessionFactory"); 
     long numberOfUsers = appUserDAO.countAll(); 

     System.out.println("Number of rows :" + numberOfUsers); 
     final String cacheRegion = AppUser.class.getCanonicalName(); 

     SecondLevelCacheStatistics settingsStatistics = sessionFactory.getStatistics(). 
      getSecondLevelCacheStatistics(cacheRegion); 
     StopWatch stopWatch = new StopWatch(); 
     stopWatch.start(); 
     appUserDAO.findAll(); 
     stopWatch.stop(); 
     System.out.println("Query time : " + stopWatch.getTotalTimeSeconds()); 
     System.out.println(settingsStatistics); 
    } 
} 

和我有

<prop key="hibernate.show_sql">false</prop> 
<prop key="hibernate.format_sql">true</prop> 
<prop key="hibernate.use_sql_comments">true</prop> 
<prop key="hibernate.cache.use_query_cache">true</prop> 
<prop key="hibernate.cache.use_second_level_cache">true</prop> 
<prop key="hibernate.generate_statistics">true</prop> 
<prop key="hibernate.cache.use_structured_entries">true</prop> 

，但我得到的輸出是這樣的：

Running testCache1 
Number of rows :81 
Query time : 0.129 
SecondLevelCacheStatistics[hitCount=0,missCount=0,putCount=81,elementCountInMemory=81,elementCountOnDisk=0,sizeInMemory=219634] 
Running testCache2 
Number of rows :81 
Query time : 0.063 
SecondLevelCacheStatistics[hitCount=0,missCount=0,putCount=81,elementCountInMemory=81,elementCountOnDisk=0,sizeInMemory=219634] 

我有什麼做的就是它的工作？

Answer 1

您的測試看起來很奇怪，您爲每個測試創建一個新的應用程序上下文，因此Hibernate SessionFactory在測試之間以及它的二級緩存之間並不存在。

正確的測試應該是這樣的：

所有的

@RunWith(SpringJUnit4ClassRunner.class) 
@ContextConfiguration(locations = { "classpath:applicationContext.xml" }) 
public class CacheTest extends AbstractTransactionalJUnit4SpringContextTests 
{ 
    @Autowired 
    private MutableDAO<AppUser> appUserDAO; 

    @Autowired 
    private SessionFactory sessionFactory; 

    private TransactionTemplate tx; 

    @Autowired 
    public void setPtm(PlatformTransactionManagement ptm) { 
     tx = new TransactionTemplate(ptm); 
    } 

    @Test 
    public void doTestCache() { 
     // Using programmatic transaction management since we need 2 transactions 
     // inside the same method 

     // 1st attempt 
     tx.execute(new TransactionCallbackWithoutResult() { 
      public void doInTransactionWithoutResult(TransactionStatus status) { 
       testCache(); 
      } 
     }); 

     // 2nd attempt 
     tx.execute(new TransactionCallbackWithoutResult() { 
      public void doInTransactionWithoutResult(TransactionStatus status) { 
       testCache(); 
      } 
     }); 

    } 

    public void testCache() { 
     long numberOfUsers = appUserDAO.countAll(); 

     System.out.println("Number of rows :" + numberOfUsers); 
     final String cacheRegion = AppUser.class.getCanonicalName(); 

     SecondLevelCacheStatistics settingsStatistics = sessionFactory.getStatistics(). 
      getSecondLevelCacheStatistics(cacheRegion); 
     StopWatch stopWatch = new StopWatch(); 
     stopWatch.start(); 
     appUserDAO.findAll(); 
     stopWatch.stop(); 
     System.out.println("Query time : " + stopWatch.getTotalTimeSeconds()); 
     System.out.println(settingsStatistics); 
    }  
} 

Answer 2

首先，請記住，Hibernate並不默認使用任何緩存提供者。所以，你需要一個Hibernate的2L緩存的「外部」緩存提供者。對於我的回答，我將使用ehcache和Hibernate 3.3。請注意，在更新版本的Hibernate中配置已更改，因此請閱讀您正在使用的確切版本的文檔。

在您的Hibernate配置中，您錯過了一個部分，即將Hibernate指向實際的提供者。該屬性hibernate.cache.provider_class爲Hibernate 3.3做到了這一點。設置它的價值net.sf.ehcache.hibernate.SingletonEhCacheProvider

現在，你還需要一個ehcache.xml中，像這樣：

<?xml version="1.0" encoding="UTF-8"?> 
<ehcache> 

    <diskStore path="./cache" /> 

    <defaultCache maxElementsInMemory="10000" 
        eternal="true" 
        overflowToDisk="true" 
        diskPersistent="true" 
        diskExpiryThreadIntervalSeconds="120" 
        memoryStoreEvictionPolicy="FIFO" /> 

    <cache name="com.mycompany.jpa.MyEntity" 
      maxElementsInMemory="50" 
      overflowToDisk="true" /> 

    <cache name="org.hibernate.cache.StandardQueryCache" 
      maxElementsInMemory="50" 
      overflowToDisk="true" /> 

    <cache name="org.hibernate.cache.UpdateTimestampsCache" 
      maxElementsInMemory="5000" 
      overflowToDisk="true" /> 

</ehcache> 

你沒有表現出你的DAO，所以，我不知道它的正確與否。請注意，您始終需要明確緩存，因爲它旨在用於特定位置的解決方案，而不是一切的通用解決方案。這意味着，在你的DAO中，你會添加一個查詢提示，指出你的查詢是可緩存的（從你的測試看來，你似乎想要查詢緩存，而不僅僅是實體緩存）。

如果您仍然無法使其工作，請參閱以下JIRA中的附件。它包含啓用緩存Maven項目，所以，你可以將它與你的代碼比較：

https://issues.jboss.org/browse/JBPAPP-4224