使用Asp.Net Core MVC 開發項目實踐[第五篇:緩存的使用]

項目中我們常常會碰到一些數據,需要高頻率用到但是又不會頻繁變動的這類,我們就可以使用緩存把這些數據緩存起來(比如說本項目的導航數據,帖子頻道數據).

我們項目中常用到有Asp.Net Core 本身提供的緩存組件MemoryCache以及第三方緩存組件Redis(當然這個不僅僅只用來做緩存工具用).

MemoryCache組件的使用:

第一步：我們在Startup類中ConfigureServices方法中添加緩存組件

services.AddMemoryCache();

第二步：我們就可以在項目中使用該緩存組件了

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Caching.Memory;
using MVCDemo.Core.Cache;
namespace MVCDemo.Web.Controllers
{
    public class CacheController : Controller
    {
        IMemoryCache _cache = null;
        public CacheController(IMemoryCache memoryCache)
        {
            _cache = memoryCache;
        }
        public IActionResult Index()
        {
            //MemoryCache示例
            string memoryCache = _cache.Get<string>("memoryCacheTest");
            if (string.IsNullOrEmpty(memoryCache))
            {
                //添加並且設置緩存
                _cache.Set<string>("memoryCacheTest", "我是memoryCacheTest緩存");
                memoryCache = _cache.Get<string>("memoryCacheTest");
            }
            ViewData["memoryCache"] = memoryCache;
            return View();
        }
    }
}

PS:在這裡我們使用的構造函數註入的方式獲取到了MemoryCache的實例對象

Redis緩存組件的使用:

PS:我們使用的是Windows系統上安裝的Redis組件,安裝教程請查看https://www.51core.net/posts/read/3048

第一步：使用Nuget添加Microsoft.Extensions.Caching.Redis組件

第二步:將Redis常用方法封裝成一個服務

1.創建一個ICacheService的介面,方便緩存組件的擴展

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace Mango.Framework.Services.Cache
 6 {
 7     public interface ICacheService
 8     {
 9         /// <summary>
10         /// 獲取緩存
11         /// </summary>
12         /// <typeparam name="T">泛型(返回的結果類型)</typeparam>
13         /// <param name="key">緩存key</param>
14         /// <returns></returns>
15         T Get<T>(string key) where T : new();
16         /// <summary>
17         /// 獲取緩存
18         /// </summary>
19         /// <param name="key">緩存key</param>
20         /// <returns></returns>
21         string Get(string key);
22         /// <summary>
23         /// 添加緩存
24         /// </summary>
25         /// <param name="key">緩存key</param>
26         /// <param name="value">緩存值</param>
27         /// <param name="ExpirationTime">絕對過期時間(分鐘)</param>
28         void Add(string key, object value, int expirationTime = 20);
29         /// <summary>
30         /// 移除緩存
31         /// </summary>
32         /// <param name="key"></param>
33         void Remove(string key);
34         /// <summary>
35         /// 更新緩存
36         /// </summary>
37         /// <param name="key"></param>
38         /// <param name="value"></param>
39         /// <param name="ExpirationTime"></param>
40         void Replace(string key, object value, int expirationTime = 20);
41     }
42 }

2.創建一個RedisCacheService類繼承自ICacheService介面並且實現介面中的方法

using System;
using System.Text;
using Microsoft.Extensions.Caching.Redis;
using Microsoft.Extensions.Caching.Distributed;
using Newtonsoft.Json;
namespace Mango.Framework.Services.Cache
{
    public class RedisCacheService:ICacheService
    {
        private RedisCache _redisCache = null;
        public RedisCacheService(RedisCacheOptions options)
        {
            _redisCache = new RedisCache(options);
        }
        /// <summary>
        /// 獲取緩存
        /// </summary>
        /// <typeparam name="T">泛型(返回的結果類型)</typeparam>
        /// <param name="key">緩存key</param>
        /// <returns></returns>
        public T Get<T>(string key) where T:new()
        {
            try
            {
                if (!string.IsNullOrEmpty(key))
                {
                    return JsonConvert.DeserializeObject<T>(Encoding.UTF8.GetString(_redisCache.Get(key)));
                }
                return default(T);
            }
            catch
            {
                return default(T);
            }
        }
        /// <summary>
        /// 獲取緩存
        /// </summary>
        /// <param name="key">緩存key</param>
        /// <returns></returns>
        public string Get(string key)
        {
            try
            {
                if (!string.IsNullOrEmpty(key))
                {
                    return Encoding.UTF8.GetString(_redisCache.Get(key));
                }
                return string.Empty;
            }
            catch
            {
                return null;
            }
        }
        /// <summary>
        /// 添加緩存
        /// </summary>
        /// <param name="key">緩存key</param>
        /// <param name="value">緩存值</param>
        /// <param name="ExpirationTime">絕對過期時間(分鐘)</param>
        public void Add(string key,object value,int expirationTime=20)
        {
            if (!string.IsNullOrEmpty(key))
            {
                _redisCache.Set(key, Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(value)), new DistributedCacheEntryOptions()
                {
                    AbsoluteExpiration = DateTimeOffset.Now.AddMinutes(expirationTime)
                });
            }
        }
        /// <summary>
        /// 移除緩存
        /// </summary>
        /// <param name="key">緩存key</param>
        public void Remove(string key)
        {
            if (!string.IsNullOrEmpty(key))
            {
                _redisCache.Remove(key);
            }
        }
        /// <summary>
        /// 更新緩存
        /// </summary>
        /// <param name="key">緩存key</param>
        /// <param name="value">緩存值</param>
        /// <param name="ExpirationTime"></param>
        public void Replace(string key, object value, int expirationTime = 20)
        {
            if (!string.IsNullOrEmpty(key))
            {
                _redisCache.Remove(key);
                _redisCache.Set(key, Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(value)), new DistributedCacheEntryOptions()
                {
                    AbsoluteExpiration = DateTimeOffset.Now.AddMinutes(expirationTime)
                });
            }
        }
    }
}

PS：該類中的構造函數負責創建Redis緩存的實例並且把相關的參數(連接字元串)傳入進行連接

第三步：在Startup類中ConfigureServices添加封裝的服務組件

//註冊自定義服務
services.AddSingleton(typeof(ICacheService), new RedisCacheService(new RedisCacheOptions()
{
      Configuration = Configuration.GetSection("Cache:ConnectionString").Value,
      InstanceName = Configuration.GetSection("Cache:InstanceName").Value
}));
//註冊到全局服務控制類中以供其它項目的使用
Framework.Services.ServiceContext.RegisterServices(services);

第四步:在項目中調用,示例代碼如下

ICacheService cacheService = ServiceContext.GetService<ICacheService>();
string cacheData = cacheService.Get("WebSiteConfigCache");

到此ASP.NET CORE MVC項目中緩存的使用介紹已經完成.