微软企业库的Cache

通常，应用程序可以将那些频繁访问的数据，以及那些需要大量处理时间来创建的数据存储在内存中，从而提高性能。基于微软的企业库，我们的快速创建一个缓存的实现。

新建PrismSample.Infrastructure.Cache

新建一个类库项目，将其命名为PrismSample.Infrastructure.Cache，然后从nuget中下载微软企业库的Cache。

然后新建我们的CacheManager类：

using Microsoft.Practices.EnterpriseLibrary.Caching;

using System.ComponentModel.Composition;

namespace PrismSample.Infrastructure.Cache

{

    [Export("PrismSampleCache", typeof(ICacheManager))]

    public class CacheManager : ICacheManager

    {

        ICacheManager _cacheManager;

        public CacheManager()

        {

            _cacheManager = CacheFactory.GetCacheManager("MemoryCacheManager");

        }

        public object this[string key]

        {

            get

            {

                return _cacheManager[key];

            }

        }

        public int Count

        {

            get

            {

                return _cacheManager.Count;

            }

        }

        public void Add(string key, object value)

        {

            _cacheManager.Add(key, value);

        }

        public void Add(string key, object value, CacheItemPriority scavengingPriority, ICacheItemRefreshAction refreshAction, params ICacheItemExpiration[] expirations)

        {

            _cacheManager.Add(key, value, scavengingPriority, refreshAction, expirations);

        }

        public bool Contains(string key)

        {

            return _cacheManager.Contains(key);

        }

        public void Flush()

        {

            _cacheManager.Flush();

        }

        public object GetData(string key)

        {

        return  _cacheManager.GetData(key);

        }

        public void Remove(string key)

        {

            _cacheManager.Remove(key);

        }

    }

}

其中MemoryCacheManager是我们稍后需要在App.config文件中配置的。

修改生成后事件：

xcopy "$(TargetPath)" "$(SolutionDir)\PrismSample\bin\Debug\" /Y

之所以添加生成后事件，是因为Cache的类库的引入不是通过Project间的项目引用来实现的，是在运行时MEF的容器去寻找指令集，所以我们把程序集都放置到运行目录下。

修改App.config配置文件

<?xml version="1.0" encoding="utf-8"?>

<configuration>

    <configSections>

        <section name="cachingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Caching.Configuration.CacheManagerSettings, Microsoft.Practices.EnterpriseLibrary.Caching" />

    </configSections>

        <startup>

            <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1" />

        </startup>

    <runtime>

        <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">

        <dependentAssembly>

            <assemblyIdentity name="Microsoft.Practices.ServiceLocation" publicKeyToken="31bf3856ad364e35" culture="neutral" />

            <bindingRedirect oldVersion="0.0.0.0-1.3.0.0" newVersion="1.3.0.0" />

        </dependentAssembly>

        </assemblyBinding>

    </runtime>

    <cachingConfiguration defaultCacheManager="MemoryCacheManager">

        <cacheManagers>

        <add name="MemoryCacheManager" type="Microsoft.Practices.EnterpriseLibrary.Caching.CacheManager, Microsoft.Practices.EnterpriseLibrary.Caching" expirationPollFrequencyInSeconds="60" maximumElementsInCacheBeforeScavenging="1000" numberToRemoveWhenScavenging="10" backingStoreName="NullBackingStore" />

        </cacheManagers>

        <backingStores>

        <add type="Microsoft.Practices.EnterpriseLibrary.Caching.BackingStoreImplementations.NullBackingStore, Microsoft.Practices.EnterpriseLibrary.Caching"

            name="NullBackingStore" />

        </backingStores>

    </cachingConfiguration>

</configuration>

配置文件的生成可以通过微软企业库的工具(配置方式)

修改Bootstrapper，将目录下符合条件的dll全部导入

using Prism.Mef;

using PrismSample.Infrastructure.Abstract.Presentation.Interface;

using System.ComponentModel.Composition.Hosting;

using System.Windows;

using Prism.Logging;

using PrismSample.Infrastructure.Logger;

using System.IO;

using System;

namespace PrismSample

{

    public class Bootstrapper : MefBootstrapper

    {

        private const string SEARCH_PATTERN = "PrismSample.Infrastructure.*.dll";

        protected override DependencyObject CreateShell()

        {

            IViewModel shellViewModel = this.Container.GetExportedValue<IViewModel>("ShellViewModel");

            return shellViewModel.View as DependencyObject;

        }

        protected override void InitializeShell()

        {

            Application.Current.MainWindow = (Shell)this.Shell;

            Application.Current.MainWindow.Show();

        }

        protected override void ConfigureAggregateCatalog()

        {

            base.ConfigureAggregateCatalog();

            //加载自己

            this.AggregateCatalog.Catalogs.Add(new AssemblyCatalog(this.GetType().Assembly));

            //加载当前目录

            DirectoryInfo dirInfo = new DirectoryInfo(@".\");

            foreach (FileInfo fileInfo in dirInfo.EnumerateFiles(SEARCH_PATTERN))

            {

                try

                {

                    this.AggregateCatalog.Catalogs.Add(new AssemblyCatalog(fileInfo.FullName));

                }

                catch (Exception ex)

                {

                    this.Logger.Log( string.Format("导入异常：{0}", ex.Message), Category.Exception, Priority.None);

                }

            }

        }

        protected override ILoggerFacade CreateLogger()

        {

            return new Logger();

        }

    }

}

测试运行

修改ShellViewModel的构造函数

[ImportingConstructor]

public ShellViewModel([Import("ShellView", typeof(IView))]IView view,

                        [Import]ILoggerFacade logger,

                        [Import("PrismSampleCache", typeof(ICacheManager))] ICacheManager _cacheManager)

{

    this.View = view;

    this.View.DataContext = this;

    _cacheManager.Add("SampleValue", "CacheValue");

    this._text = _cacheManager.GetData("SampleValue").ToString();

    logger.Log("ShellViewModel Created", Category.Info, Priority.None);

}

运行结果：

小结

本文用微软企业库实现了一个简单的缓存系统。
源码下载

参考信息

patterns & practices – Enterprise Library
黄聪：Microsoft Enterprise Library 5.0 系列教程(一) : Caching Application Block (初级)