您正在使用共享缓存（缓存服务预览版） - 其他两个选项是“角色”缓存 - 在Windows Azure Cache上阅读更多内容。假设您在配置中的所有设置都是正确的，那么，您没有正确实例化缓存。阅读如何使用 Windows Azure 缓存服务（预览版）。您需要使用：
DataCache cache = new DataCache("default");
或者：
// Cache client configured by settings in application configuration file.
DataCacheFactory cacheFactory = new DataCacheFactory();
DataCache cache = cacheFactory.GetDefaultCache();
// Or DataCache cache = cacheFactory.GetCache("default");
// cache can now be used to add and retrieve items.
最后，创建缓存对象的成本很高——您应该为缓存创建一个新的单例类，以便创建一次——而不是每次调用操作时。这是单例类的完整示例：
public static class MyCache
{
private static DataCacheFactory _cacheFactory = null;
private static ObjectCache Cache
{
get
{
return MemoryCache.Default;
}
}
private static DataCache ACache
{
get
{
if (_cacheFactory == null)
{
try
{
_retryPolicy.ExecuteAction(() => { _cacheFactory = new DataCacheFactory(); });
return _cacheFactory == null ? null : _cacheFactory.GetDefaultCache();
}
catch (Exception ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
return null;
}
}
return _cacheFactory.GetDefaultCache();
}
}
public static void FlushCache()
{
ACache.Clear();
}
// Define your retry strategy: retry 3 times, 1 second apart.
private static readonly FixedInterval _retryStrategy = new FixedInterval(3, TimeSpan.FromSeconds(1));
// Define your retry policy using the retry strategy and the Windows Azure storage
// transient fault detection strategy.
private static RetryPolicy _retryPolicy = new RetryPolicy<StorageTransientErrorDetectionStrategy>(_retryStrategy);
// Private constructor to prevent instantiation
// and force consumers to use the Instance property
static MyCache()
{ }
/// <summary>
/// Add an item to the cache with a key and set a absolute expiration on it
/// </summary>
public static void Add(string key, object value, int minutes = 90)
{
try
{
if (RoleEnvironment.IsAvailable)
{
_retryPolicy.ExecuteAction(() => { ACache.Put(key, value, TimeSpan.FromMinutes(minutes)); });
}
else
{
Cache.Add(key, value, new CacheItemPolicy { AbsoluteExpiration = DateTime.Now + TimeSpan.FromMinutes(minutes) });
}
}
catch (Exception ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
}
}
/// <summary>
/// Add the object with the specified key to the cache if it does not exist, or replace the object if it does exist and set a absolute expiration on it
/// only valid for Azure caching
/// </summary>
public static void Put(string key, object value, int minutes = 90)
{
try
{
if (RoleEnvironment.IsAvailable)
{
_retryPolicy.ExecuteAction(() => { ACache.Put(key, value, TimeSpan.FromMinutes(minutes)); });
}
else
{
Cache.Add(key, value, new CacheItemPolicy { AbsoluteExpiration = DateTime.Now + TimeSpan.FromMinutes(minutes) });
}
}
catch (Exception ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
}
}
/// <summary>
/// Get a strongly typed item out of cache
/// </summary>
public static T Get<T>(string key) where T : class
{
try
{
object value = null;
if (RoleEnvironment.IsAvailable)
{
_retryPolicy.ExecuteAction(() => { value = ACache.Get(key); });
}
else
{
value = Cache[key];
}
if (value != null) return (T) value;
return null;
}
catch (DataCacheException ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
return null;
}
catch (Exception ex)
{
ErrorSignal.FromCurrentContext().Raise(ex);
return null;
}
}
/// <summary>
/// Microsoft's suggested method for cleaning up resources such as this in a static class
/// to ensure connections and other consumed resources are returned to the resource pool
/// as quickly as possible.
/// </summary>
public static void Uninitialize()
{
if (_cacheFactory == null) return;
_cacheFactory.Dispose();
_cacheFactory = null;
}
}
