[Winform]缓存处理

摘要

在对winform做的项目优化的时候，首先想到的是对查询，并不经常变化的数据进行缓存，但对web项目来说有System.Web.Caching.Cache类进行缓存，那么winform端该如何呢？你可能会想到，存到文件中，但那可能有问题，文件操作权限问题，IO操作性能问题。

解决办法

针对exe的项目，可以使用MemoryCache这个类，进行内存级别的缓存。

辅助类

    /// <summary>
    /// 基于MemoryCache的缓存辅助类
    /// </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>
        /// 移除缓存
        /// </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;
        }
    }

测试

  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("获取缓存中数据");
            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;
        }
    }