我正在尝试使用 Memcached 设置 Spring 3.1 缓存解决方案。我已经成功地合并了 ehcache（Spring 已经内置了对此的支持）。但是，我遇到了 memcached 的问题。我提前为长度道歉（它主要是样板代码）......
我正在使用 Java 配置，所以我注释了我的控制器配置以启用缓存，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
}
这设置了三个控制器，允许对 Stock 元素进行基本的 CRUD 操作。业务对象如下所示：
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
}
我正在使用 MyBatis，所以我为 Stock 对象创建了一个 Mapper。然后将映射器注入到我的 DAO 中，然后将 DAO 注入到服务中。工作缓存（在两种实现中）发生在“服务”层中。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);
}
}
这是示例控制器，它应该缓存显示所有股票的结果（当从数据库中添加、更新或删除股票时，此缓存将被完全清除）：
@Controller
public class ListAllStocksController {
@Autowired
private TradingService tradingService;
@Cacheable("viewCache")
@RequestMapping(value = "listStocks.html", method = RequestMethod.GET)
public ModelAndView displayAllStocks() {
//The SerializableModelAndView extends Spring's ModelAndView and implements Serializable due to spymemcached not being able to add a non-serializable object to the cache
final ModelAndView mav = new SerializableModelAndView("listStocks");
mav.addObject("stocks", tradingService.getAll());
return mav;
}
@CacheEvict(value = "viewCache", allEntries = true)
@RequestMapping(value = "editStock.html", method = RequestMethod.POST, params = "submit=Edit")
public ModelAndView editStock(final Stock stock, final BindingResult result) {
final ModelAndView mav = new ModelAndView("redirect:listStocks.html");
tradingService.updateStock(stock);
return mav;
}
@CacheEvict(value = "viewCache", allEntries = true)
@RequestMapping(value = "listStocks.html", method = RequestMethod.POST, params = "submit=Delete")
public ModelAndView deleteStockAction(@RequestParam("name") final String name) {
final ModelAndView mav = new ModelAndView("redirect:listStocks.html");
tradingService.removeStock(stock);
return mav;
}
}
这是我的小缓存管理器：
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;
}
}
这是我的 MemCache 类的样子：
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();
}
}
我已经用 CouchBase 和常规 memcached 尝试过这个。下面的设置显示 memcached 仅自行启动。
@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();
}
}
在上面的示例中，我们将简单地使用 memcached。这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记录：
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，这是一个全新的发布，缓存中应该没有任何内容。我现在将一个股票添加到缓存中：
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 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
这里有趣的是，当我向系统添加股票时，我被重定向到 displayAllStocks 方法。它最初是正确的，但是如果我刷新页面，我会收到原始版本（显示没有库存的版本）。我被困在这里，并且不确定此时可能导致此问题的原因。如果我以任何方式使缓存无效，则重定向可以正常工作。在随后的刷新中，我检索了似乎是放入的第一个值（已被删除）
这是配置问题吗？memcache 或 spymemcached 中的限制/错误，还是我的 MemCache 代码中的错误？