[Winform]緩存處理

摘要

在對winform做的項目優化的時候，首先想到的是對查詢，並不經常變化的數據進行緩存，但對web項目來說有System.Web.Caching.Cache類進行緩存，那么winform端該如何呢？你可能會想到，存到文件中，但那可能有問題，文件操作權限問題，IO操作性能問題。

解決辦法

針對exe的項目，可以使用MemoryCache這個類，進行內存級別的緩存。

輔助類

    /// <summary>
    /// 基於MemoryCache的緩存輔助類
    /// </summary>
    public static class MemoryCacheHelper
    {
        private static readonly Object _locker = new object();

        public static T FindCacheItem<T>(string key, Func<T> cachePopulate, TimeSpan? slidingExpiration = null,
 DateTime? absoluteExpiration = null)
        {
            if (String.IsNullOrWhiteSpace(key))
            {
                throw new ArgumentException("Invalid cache key");
            }
            if (cachePopulate == null)
            {
                throw new ArgumentNullException("cachePopulate");
            }
            if (slidingExpiration == null && absoluteExpiration == null)
            {
                throw new ArgumentException("Either a sliding expiration or absolute must be provided");
            }

            if (MemoryCache.Default[key] == null)
            {
                lock (_locker)
                {
                    if (MemoryCache.Default[key] == null)
                    {
                        var item = new CacheItem(key, cachePopulate());
                        var policy = CreatePolicy(slidingExpiration, absoluteExpiration);

                        MemoryCache.Default.Add(item, policy);
                    }
                }
            }

            return (T)MemoryCache.Default[key];
        }
        /// <summary>
        /// 移除緩存
        /// </summary>
        /// <param name="key"></param>
        public static void RemoveCache(string key)
        {
            MemoryCache.Default.Remove(key);
        }
        private static CacheItemPolicy CreatePolicy(TimeSpan? slidingExpiration, DateTime? absoluteExpiration)
        {
            var policy = new CacheItemPolicy();

            if (absoluteExpiration.HasValue)
            {
                policy.AbsoluteExpiration = absoluteExpiration.Value;
            }
            else if (slidingExpiration.HasValue)
            {
                policy.SlidingExpiration = slidingExpiration.Value;
            }

            policy.Priority = CacheItemPriority.Default;

            return policy;
        }
    }

測試

  class Program
    {
        static void Main(string[] args)
        {
            string cacheKey = "person_key";
            Person p = MemoryCacheHelper.FindCacheItem<Person>(cacheKey,
                () =>
                {
                    return new Person() { Id = Guid.NewGuid(), Name = "wolfy" };
                }, new TimeSpan(0, 30, 0));
            if (p != null)
            {
                Console.WriteLine(p.ToString());
            }
            Console.WriteLine("獲取緩存中數據");
            Person p2 = MemoryCacheHelper.FindCacheItem<Person>(cacheKey,
                () =>
                {
                    return new Person() { Id = Guid.NewGuid(), Name = "wolfy" };
                }, new TimeSpan(0, 30, 0));
            if (p2 != null)
            {
                Console.WriteLine(p2.ToString());
            }
            MemoryCacheHelper.RemoveCache(cacheKey);
            Person p3 = MemoryCacheHelper.FindCacheItem<Person>(cacheKey,
               () =>
               {
                   return new Person() { Id = Guid.NewGuid(), Name = "wolfy" };
               }, new TimeSpan(0, 30, 0));
            if (p3 != null)
            {
                Console.WriteLine(p3.ToString());
            }
            Console.Read();
        }

    }
    public class Person
    {
        public Guid Id { set; get; }
        public string Name { set; get; }
        public override string ToString()
        {
            return Id.ToString() + "\t" + Name;
        }
    }

參考

http://www.cnblogs.com/ldy_ai/p/3939954.html

https://msdn.microsoft.com/en-us/library/system.runtime.caching.memorycache(v=vs.110).aspx