分享基于MemoryCache(内存缓存)的缓存工具类,C# B/S 、C/S项目均可以使用!
2021-02-15 03:19
using System; using System.Collections.Generic; using System.Linq; using System.Runtime.Caching; using System.Text; using System.Threading.Tasks; namespace AutoLogisticsPH.Common.Utils { ////// 基于MemoryCache(内存缓存)的缓存工具类 /// Author:左文俊 /// Date:2017/12/11 /// public static class MemoryCacheUtil { private static readonly Object _locker = new object(), _locker2 = new object(); ////// 取缓存项,如果不存在则返回空 /// ////// /// public static T GetCacheItem (String key) { try { return (T)MemoryCache.Default[key]; } catch { return default(T); } } /// /// 是否包含指定键的缓存项 /// /// ///public static bool Contains(string key) { return MemoryCache.Default.Contains(key); } /// /// 取缓存项,如果不存在则新增缓存项 /// ////// /// /// /// /// public static T GetOrAddCacheItem (String key, Func 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) { T cacheValue = cachePopulate(); if (!typeof(T).IsValueType && ((object)cacheValue) == null) //如果是引用类型且为NULL则不存缓存 { return cacheValue; } var item = new CacheItem(key, cacheValue); var policy = CreatePolicy(slidingExpiration, absoluteExpiration); MemoryCache.Default.Add(item, policy); } } } return (T)MemoryCache.Default[key]; } /// /// 取缓存项,如果不存在则新增缓存项 /// ////// /// /// /// public static T GetOrAddCacheItem (String key, Func cachePopulate, string dependencyFilePath) { if (String.IsNullOrWhiteSpace(key)) throw new ArgumentException("Invalid cache key"); if (cachePopulate == null) throw new ArgumentNullException("cachePopulate"); if (MemoryCache.Default[key] == null) { lock (_locker2) { if (MemoryCache.Default[key] == null) { T cacheValue = cachePopulate(); if (!typeof(T).IsValueType && ((object)cacheValue) == null) //如果是引用类型且为NULL则不存缓存 { return cacheValue; } var item = new CacheItem(key, cacheValue); var policy = CreatePolicy(dependencyFilePath); MemoryCache.Default.Add(item, policy); } } } return (T)MemoryCache.Default[key]; } /// /// 移除指定键的缓存项 /// /// public static void RemoveCacheItem(string key) { try { MemoryCache.Default.Remove(key); } catch { } } 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; } private static CacheItemPolicy CreatePolicy(string filePath) { CacheItemPolicy policy = new CacheItemPolicy(); policy.ChangeMonitors.Add(new HostFileChangeMonitor(new List() { filePath })); policy.Priority = CacheItemPriority.Default; return policy; } } }
支持:可指定绝对过期时间、滑动过期明间、文件依赖 三种缓存方式,目前已在公司各种生产业务项目中有使用。优点是可以根据数据的使用频率设置缓存有效期,特别是文件依赖缓存,比如:连接字符串读取一次后,若CONFIG文件没有改变,则缓存永久有效,一旦CONFIG更改,则缓存失效需重新读取,保证数据缓存的最大可用性,减少不必要的多次重复读取CONFIG。
使用示例很简单:(如下:会在第一次读取连接字符串并解密后返回给connstr变量,后续直接通过缓存KEY dbConnName直接返回连接字符串的结果,若修改了连接字符串的CONFIG文件,则缓存的项会失效,会重新读取连接字符串并重新加入到缓存中)
string connstr= MemoryCacheUtil.GetOrAddCacheItem(dbConnName, () =>
{
var connStrSettings = ConfigUtil.GetConnectionString(dbConnName,dbConnectionStringConfigPath);
string dbProdName = connStrSettings.ProviderName;
string dbConnStr = connStrSettings.ConnectionString;
return EncryptUtil.Decrypt(dbConnStr);
}, "缓存依赖文件路路,如:c:\app\app.config");
文章标题:分享基于MemoryCache(内存缓存)的缓存工具类,C# B/S 、C/S项目均可以使用!
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