Java Memcached+Spring缓存

我正在尝试使用Memcached设置Spring3.1缓存解决方案。我已经成功地将ehcache Spring内置的对这一点的支持合并到一起。然而，我被memcached的一个问题困住了。我很抱歉提前这么长时间，大部分都是样板代码

我使用的是Java配置，因此我对控制器配置进行了注释，以启用缓存，如下所示

@Configuration  @EnableWebMvc  @EnableCaching 
@ComponentScan("com.ehcache.reference.web")
public class ControllerConfig extends WebMvcConfigurerAdapter {
   //Bean to create ViewResolver and add the Resource handler
}

这将设置三个控制器，允许对库存元素执行基本CRUD操作。业务对象看起来像：

public class Stock implements Serializable {
  private String name;
  private double cost; //This isn't a real app, don't care about correctness of value
  //Getters, Setters contructors, etc... left out just a standard POJO

public class MemCache implements Cache {

  private MemcachedClient cache;
  private final String name;
  private static final Logger LOGGER = Logger.getLogger(MemCache.class);

  public MemCache(final String name, final int port) throws URISyntaxException {
    this.name = name;
    try {
      cache = new MemcachedClient(AddrUtil.getAddresses("localhost:" + port));
      final SerializingTranscoder stc = (SerializingTranscoder) cache.getTranscoder();
      stc.setCompressionThreshold(600000);
    } catch (final IOException e) { //Let it attempt to reconnect }
  }

  @Override
  public String getName() {
    return name;
  }

  @Override
  public Object getNativeCache() {
    return cache;
  }

  @Override
  public ValueWrapper get(final Object key) {
    Object value = null;
    try {
      value = cache.get(key.toString());
    } catch (final Exception e) {
      LOGGER.warn(e);
    }
    if (value == null) {
      return null;
    }
    return new SimpleValueWrapper(value);
  }

  @Override
  public void put(final Object key, final Object value) {
    cache.set(key.toString(), 7 * 24 * 3600, value);
    Assert.assertNotNull(get(key)); //This fails on the viewCache
  }

  @Override
  public void evict(final Object key) {
    this.cache.delete(key.toString());
  }

  @Override
  public void clear() {
    cache.flush();
  }
}

}

我正在使用MyBatis，因此我为Stock对象创建了一个映射器。映射器然后被注入到我的DAO中，DAO随后被注入到服务中。两种实现中的工作缓存都发生在服务层。下面是使用注入的DAO的服务层：

public class TradingServiceImpl implements TradingService {

  @Autowired
  private final StockDao stockDao;

  public TradingServiceImpl(final StockDao stockDao) {
    this.stockDao = stockDao;
  }

  @Override
  public void addNewStock(final Stock stock) {
    stockDao.save(stock);
  }

  @Override
  @Cacheable(value = "stockCache")
  public Stock getStock(final String stockName) {
    return stockDao.findByName(stockName);
  }

  @Override
  public List<Stock> getAll() {
    return stockDao.findAll();
  }

  @Override
  @CacheEvict(value = "stockCache", key = "#stock.name")
  public void removeStock(final Stock stock) {
    stockDao.delete(stock);
  }

  @Override
  @CacheEvict(value = "stockCache", key = "#stock.name")
  public void updateStock(final Stock stock) {
    stockDao.update(stock);
  }
}

这是我的小型CacheManager：

public class MemCacheManager extends AbstractCacheManager {
  private final Collection<MemCache> internalCaches;

  public MemCacheManager(final Collection<MemCache> internalCaches) {
    this.internalCaches = internalCaches;
  }

  @Override
  protected Collection<? extends Cache> loadCaches() {
    Assert.notNull(internalCaches, "A collection caches is required and cannot be empty");
    return internalCaches;
  }
}

我用CouchBase和普通memcached都试过了。下面的设置显示memcached仅由自身启动

@Configuration @EnableCaching @Profile("memcached")
public class MemCacheConfiguration implements CachingConfigurer {

  @Override @Bean
  public CacheManager cacheManager() {
    CacheManager cacheManager;
    try {
      cacheManager = new MemCacheManager(internalCaches());
      return cacheManager;
    } catch (final URISyntaxException e) {
      throw new RuntimeException(e);
    }
  }

  @Bean
  public Collection<MemCache> internalCaches() throws URISyntaxException {
    final Collection<MemCache> caches = new ArrayList<MemCache>();
    // caches.add(new MemCache("stockCache", 11212));
    caches.add(new MemCache("viewCache", 11211));
    return caches;
  }

  @Override
  public KeyGenerator keyGenerator() {
    return new DefaultKeyGenerator();
  }

}

在上面的例子中，我们只是使用memcached。以下是我第一次启动应用程序并点击列表控制器时看到的日志：

58513 [qtp1656205248-16] TRACE org.springframework.cache.interceptor.CacheInterceptor  - Computed cache key 0 for operation CacheableOperation[public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.ListAllStocksController.displayAllStocks()] caches=[viewCache] | condition='' | key='0'
58519 [qtp1656205248-16] WARN  com.memcache.MemCache  - Retrieved: null from the cache 'viewCache' at <0> key of type <java.lang.Integer>
58519 [qtp1656205248-16] ERROR com.memcache.MemCache  - Returning null
58520 [qtp1656205248-16] DEBUG org.mybatis.spring.SqlSessionUtils  - Creating a new SqlSession
58520 [qtp1656205248-16] DEBUG org.mybatis.spring.SqlSessionUtils  - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@640f434f] was not registered for synchronization because synchronization is not active
58520 [qtp1656205248-16] DEBUG org.mybatis.spring.transaction.SpringManagedTransaction  - JDBC Connection [org.hsqldb.jdbc.JDBCConnection@260c2adb] will not be managed by Spring
58521 [qtp1656205248-16] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ooo Using Connection [org.hsqldb.jdbc.JDBCConnection@260c2adb]
58521 [qtp1656205248-16] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==>  Preparing: SELECT * from STOCK
58521 [qtp1656205248-16] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==> Parameters:
58521 [qtp1656205248-16] DEBUG org.mybatis.spring.SqlSessionUtils  - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@640f434f]
58521 [qtp1656205248-16] WARN  com.memcache.MemCache  - Setting: ModelAndView: reference to view with name 'listStocks'; model is {stocks=[]} into the cache 'viewCache' at <0> key of type <java.lang.Integer>
58527 [qtp1656205248-16] WARN  com.memcache.MemCache  - Retrieved: ModelAndView: materialized View is [null]; model is null from the cache 'viewCache' at <0> key of type <java.lang.Integer>

这一切看起来都是正确的，这是一个新的启动缓存中应该没有任何内容。现在，我将向缓存中添加股票：

263036 [qtp1656205248-14] DEBUG org.mybatis.spring.SqlSessionUtils  - Creating a new SqlSession
263036 [qtp1656205248-14] DEBUG org.mybatis.spring.SqlSessionUtils  - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3d20b8d5] was not registered for synchronization because synchronization is not active
263038 [qtp1656205248-14] DEBUG org.mybatis.spring.transaction.SpringManagedTransaction  - JDBC Connection [org.hsqldb.jdbc.JDBCConnection@40b5f9bb] will not be managed by Spring
263038 [qtp1656205248-14] DEBUG com.ehcache.reference.dao.StockMapper.save  - ooo Using Connection [org.hsqldb.jdbc.JDBCConnection@40b5f9bb]
263038 [qtp1656205248-14] DEBUG com.ehcache.reference.dao.StockMapper.save  - ==>  Preparing: INSERT INTO STOCK (name, cost) VALUES (?, ?)
263039 [qtp1656205248-14] DEBUG com.ehcache.reference.dao.StockMapper.save  - ==> Parameters: A(String), 1.0(Double)
263039 [qtp1656205248-14] DEBUG org.mybatis.spring.SqlSessionUtils  - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@3d20b8d5]
263039 [qtp1656205248-14] TRACE org.springframework.cache.interceptor.CacheInterceptor  - Invalidating cache key 0 for operation CacheEvictOperation[public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.AddStockController.addNewStock(com.ehcache.reference.business.Stock,org.springframework.validation.BindingResult)] caches=[viewCache] | condition='' | key='0',false,false on method public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.AddStockController.addNewStock(com.ehcache.reference.business.Stock,org.springframework.validation.BindingResult)
263039 [qtp1656205248-14] WARN  com.memcache.MemCache  - Evicting value at <0> in cache 'viewCache'
263049 [qtp1656205248-18] TRACE org.springframework.cache.interceptor.CacheInterceptor  - Computed cache key 0 for operation CacheableOperation[public org.springframework.web.servlet.ModelAndView com.ehcache.reference.web.ListAllStocksController.displayAllStocks()] caches=[viewCache] | condition='' | key='0'
263051 [qtp1656205248-18] WARN  com.memcache.MemCache  - Retrieved: null from the cache 'viewCache' at <0> key of type <java.lang.Integer>
263051 [qtp1656205248-18] ERROR com.memcache.MemCache  - Returning null
263051 [qtp1656205248-18] DEBUG org.mybatis.spring.SqlSessionUtils  - Creating a new SqlSession
263051 [qtp1656205248-18] DEBUG org.mybatis.spring.SqlSessionUtils  - SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7050d0a7] was not registered for synchronization because synchronization is not active
263051 [qtp1656205248-18] DEBUG org.mybatis.spring.transaction.SpringManagedTransaction  - JDBC Connection [org.hsqldb.jdbc.JDBCConnection@49b2bd8c] will not be managed by Spring
263051 [qtp1656205248-18] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ooo Using Connection [org.hsqldb.jdbc.JDBCConnection@49b2bd8c]
263051 [qtp1656205248-18] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==>  Preparing: SELECT * from STOCK
263052 [qtp1656205248-18] DEBUG com.ehcache.reference.dao.StockMapper.findAll  - ==> Parameters:
263053 [qtp1656205248-18] DEBUG org.mybatis.spring.SqlSessionUtils  - Closing non transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@7050d0a7]
263053 [qtp1656205248-18] WARN  com.memcache.MemCache  - Setting: ModelAndView: reference to view with name 'listStocks'; model is {stocks=[Stock Name: <A>      Current Cost <1.0>]} into the cache 'viewCache' at <0> key of type <java.lang.Integer>
263055 [qtp1656205248-18] WARN  com.memcache.MemCache  - Retrieved: ModelAndView: materialized View is [null]; model is null from the cache 'viewCache' at <0> key of type <java.lang.Integer>

减去最后一行，这一切看起来都是正确的。这是我从memcached-vv的输出：

<156 get 0               ##Initial listing of all
>156 END                 
<156 set 0 1 604800 79   ##Cache initial result on startup
>156 STORED
<156 get 0
>156 sending key 0
>156 END
<156 delete 0            ##Invalidation when stock added
>156 DELETED
<156 get 0               ##Add redirects to the get page
>156 END
<156 set 0 1 604800 79   ##Store the new value
>156 STORED
<156 get 0
>156 sending key 0       ##Refresh the page
>156 END

这里的unfun位是当我向系统添加股票时，我被重定向到displayAllStocks方法。它最初这样做是正确的，但是如果我刷新页面，我会被发送到原始版本，即不显示库存的版本。我被困在这里，不确定是什么导致了这个问题。如果我以任何方式使缓存无效，重定向将正常工作。在随后的刷新中，我检索到的似乎是第一个被删除的值

---

这是配置问题吗？memcache或SpymeMached中的限制/错误，或者只是我的memcache代码中的错误？

在TradingServiceImpl中，getStock方法始终从缓存返回相同的对象，而不依赖于股票名称。您应该将其更改为：

  @Override
  @Cacheable(value = "stockCache", key="#stockName")
  public Stock getStock(final String stockName) {
    return stockDao.findByName(stockName);
  }

在哪里逐出viewCache？我在你的代码里没看到

如果您想在Spring3.1缓存抽象上使用memcached，您可以使用简单的SpringMemcached当前快照版本—您需要从源代码构建它。您可以找到如何使用SSM将memcached与Spring Cache集成的示例配置。 示例项目：SSM svn中提供了使用此集成的功能

---

更新：3.0.0与Spring Cache集成已经可用。

您可以检查每个步骤中memcached中存储的内容吗？使用putty/telent连接到memcached服务器，并检查viewCache是否已更新。上面的日志仅显示viewCache。我可以看到设置了一个值，但它不是正确的值。我猜是因为扩展模型和视图实现了serializable，而有些东西没有被正确序列化。您可以尝试简单的Spring Memcached和JSON序列化，这样您就可以看到缓存中到底存储了什么？

  @Override
  @Cacheable(value = "stockCache", key="#stockName")
  public Stock getStock(final String stockName) {
    return stockDao.findByName(stockName);
  }