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# 使用Redis缓存数据

上一篇文章完成了项目的全局异常处理和日志记录。

在日志记录中使用的静态方法有人指出写法不是很优雅，遂优化一下上一篇中日志记录的方法，具体操作如下：

在.ToolKits层中新建扩展方法Log4NetExtensions.cs。

//Log4NetExtensions.cs
using log4net;
using log4net.Config;
using Microsoft.Extensions.Hosting;
using System.IO;
using System.Reflection;

namespace Meowv.Blog.ToolKits.Extensions
{
    public static class Log4NetExtensions
    {
        public static IHostBuilder UseLog4Net(this IHostBuilder hostBuilder)
        {
            var log4netRepository = LogManager.GetRepository(Assembly.GetEntryAssembly());
            XmlConfigurator.Configure(log4netRepository, new FileInfo("log4net.config"));

            return hostBuilder;
        }
    }
}
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配置log4net，然后我们直接返回IHostBuilder对象，便于在Main方法中链式调用。

//Program.cs
using Meowv.Blog.ToolKits.Extensions;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;
using System.Threading.Tasks;

namespace Meowv.Blog.HttpApi.Hosting
{
    public class Program
    {
        public static async Task Main(string[] args)
        {
            await Host.CreateDefaultBuilder(args)
                      .UseLog4Net()
                      .ConfigureWebHostDefaults(builder =>
                      {
                          builder.UseIISIntegration()
                                 .UseStartup<Startup>();
                      }).UseAutofac().Build().RunAsync();
        }
    }
}
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然后修改MeowvBlogExceptionFilter过滤器，代码如下：

//MeowvBlogExceptionFilter.cs
using log4net;
using Microsoft.AspNetCore.Mvc.Filters;

namespace Meowv.Blog.HttpApi.Hosting.Filters
{
    public class MeowvBlogExceptionFilter : IExceptionFilter
    {
        private readonly ILog _log;

        public MeowvBlogExceptionFilter()
        {
            _log = LogManager.GetLogger(typeof(MeowvBlogExceptionFilter));
        }

        /// <summary>
        /// 异常处理
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public void OnException(ExceptionContext context)
        {
            // 错误日志记录
            _log.Error($"{context.HttpContext.Request.Path}|{context.Exception.Message}", context.Exception);
        }
    }
}
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可以删掉之前添加的LoggerHelper.cs类，运行一下，同样可以达到预期效果。

本篇将集成Redis，使用Redis来缓存数据，使用方法参考的微软官方文档：https://docs.microsoft.com/zh-cn/aspnet/core/performance/caching/distributed (opens new window)

关于Redis的介绍这里就不多说了，这里有一篇快速入门的文章：Redis快速入门及使用 (opens new window)，对于不了解的同学可以看看。

直入主题，先在appsettings.json配置Redis的连接字符串。

//appsettings.json
...
  "Caching": {
    "RedisConnectionString": "127.0.0.1:6379,password=123456,ConnectTimeout=15000,SyncTimeout=5000"
  }
...
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对应的，在AppSettings.cs中读取。

//AppSettings.cs
...
    /// <summary>
    /// Caching
    /// </summary>
    public static class Caching
    {
        /// <summary>
        /// RedisConnectionString
        /// </summary>
        public static string RedisConnectionString => _config["Caching:RedisConnectionString"];
    }
...
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在.Application.Caching层添加包Microsoft.Extensions.Caching.StackExchangeRedis，然后在模块类MeowvBlogApplicationCachingModule中添加配置缓存实现。

//MeowvBlogApplicationCachingModule.cs
using Meowv.Blog.Domain;
using Meowv.Blog.Domain.Configurations;
using Microsoft.Extensions.DependencyInjection;
using Volo.Abp.Caching;
using Volo.Abp.Modularity;

namespace Meowv.Blog.Application.Caching
{
    [DependsOn(
        typeof(AbpCachingModule),
        typeof(MeowvBlogDomainModule)
    )]
    public class MeowvBlogApplicationCachingModule : AbpModule
    {
        public override void ConfigureServices(ServiceConfigurationContext context)
        {
            context.Services.AddStackExchangeRedisCache(options =>
            {
                options.Configuration = AppSettings.Caching.RedisConnectionString;
                //options.InstanceName
                //options.ConfigurationOptions
            });
        }
    }
}
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options.Configuration是 Redis 的连接字符串。

options.InstanceNam是 Redis 实例名称，这里没填。

options.ConfigurationOptions是 Redis 的配置属性，如果配置了这个字，将优先于 Configuration 中的配置，同时它支持更多的选项。我这里也没填。

紧接着我们就可以直接使用了，直接将IDistributedCache接口依赖关系注入即可。

可以看到默认已经实现了这么多常用的接口，已经够我这个小项目用的了，同时在Microsoft.Extensions.Caching.Distributed.DistributedCacheExtensions中微软还给我们提供了很多扩展方法。

于是，我们我就想到写一个新的扩展方法，可以同时处理获取和添加缓存的操作，当缓存存在时，直接返回，不存在时，添加缓存。

新建MeowvBlogApplicationCachingExtensions.cs扩展方法，如下：

//MeowvBlogApplicationCachingExtensions.cs
using Meowv.Blog.ToolKits.Extensions;
using Microsoft.Extensions.Caching.Distributed;
using System;
using System.Threading.Tasks;

namespace Meowv.Blog.Application.Caching
{
    public static class MeowvBlogApplicationCachingExtensions
    {
        /// <summary>
        /// 获取或添加缓存
        /// </summary>
        /// <typeparam name="TCacheItem"></typeparam>
        /// <param name="cache"></param>
        /// <param name="key"></param>
        /// <param name="factory"></param>
        /// <param name="minutes"></param>
        /// <returns></returns>
        public static async Task<TCacheItem> GetOrAddAsync<TCacheItem>(this IDistributedCache cache, string key, Func<Task<TCacheItem>> factory, int minutes)
        {
            TCacheItem cacheItem;

            var result = await cache.GetStringAsync(key);
            if (string.IsNullOrEmpty(result))
            {
                cacheItem = await factory.Invoke();

                var options = new DistributedCacheEntryOptions();
                if (minutes != CacheStrategy.NEVER)
                {
                    options.AbsoluteExpiration = DateTimeOffset.Now.AddMinutes(minutes);
                }

                await cache.SetStringAsync(key, cacheItem.ToJson(), options);
            }
            else
            {
                cacheItem = result.FromJson<TCacheItem>();
            }

            return cacheItem;
        }
    }
}
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我们可以在DistributedCacheEntryOptions中可以配置我们的缓存过期时间，其中有一个判断条件，就是当minutes = -1的时候，不指定过期时间，那么我们的缓存就不会过期了。

GetStringAsync()、SetStringAsync()是DistributedCacheExtensions的扩展方法，最终会将缓存项cacheItem转换成JSON格式进行存储。

CacheStrategy是在.Domain.Shared层定义的缓存过期时间策略常量。

//MeowvBlogConsts.cs
...
        /// <summary>
        /// 缓存过期时间策略
        /// </summary>
        public static class CacheStrategy
        {
            /// <summary>
            /// 一天过期24小时
            /// </summary>

            public const int ONE_DAY = 1440;

            /// <summary>
            /// 12小时过期
            /// </summary>

            public const int HALF_DAY = 720;

            /// <summary>
            /// 8小时过期
            /// </summary>

            public const int EIGHT_HOURS = 480;

            /// <summary>
            /// 5小时过期
            /// </summary>

            public const int FIVE_HOURS = 300;

            /// <summary>
            /// 3小时过期
            /// </summary>

            public const int THREE_HOURS = 180;

            /// <summary>
            /// 2小时过期
            /// </summary>

            public const int TWO_HOURS = 120;

            /// <summary>
            /// 1小时过期
            /// </summary>

            public const int ONE_HOURS = 60;

            /// <summary>
            /// 半小时过期
            /// </summary>

            public const int HALF_HOURS = 30;

            /// <summary>
            /// 5分钟过期
            /// </summary>
            public const int FIVE_MINUTES = 5;

            /// <summary>
            /// 1分钟过期
            /// </summary>
            public const int ONE_MINUTE = 1;

            /// <summary>
            /// 永不过期
            /// </summary>

            public const int NEVER = -1;
        }
...
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接下来去创建缓存接口类和实现类，然后再我们的引用服务层.Application中进行调用，拿上一篇中接入GitHub的几个接口来做新增缓存操作。

和.Application层格式一样，在.Application.Caching中新建Authorize文件夹，添加缓存接口IAuthorizeCacheService和实现类AuthorizeCacheService。

注意命名规范，实现类肯定要继承一个公共的CachingServiceBase基类。在.Application.Caching层根目录添加MeowvBlogApplicationCachingServiceBase.cs，继承ITransientDependency。

//MeowvBlogApplicationCachingServiceBase.cs
using Microsoft.Extensions.Caching.Distributed;
using Volo.Abp.DependencyInjection;

namespace Meowv.Blog.Application.Caching
{
    public class CachingServiceBase : ITransientDependency
    {
        public IDistributedCache Cache { get; set; }
    }
}
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然后使用属性注入的方式，注入IDistributedCache。这样我们只要继承了基类：CachingServiceBase，就可以愉快的使用缓存了。

添加要缓存的接口到IAuthorizeCacheService，在这里我们使用Func()方法，我们的接口返回什么类型由Func()来决定，于是添加三个接口如下：

//IAuthorizeCacheService.cs
using Meowv.Blog.ToolKits.Base;
using System;
using System.Threading.Tasks;

namespace Meowv.Blog.Application.Caching.Authorize
{
    public interface IAuthorizeCacheService
    {
        /// <summary>
        /// 获取登录地址(GitHub)
        /// </summary>
        /// <returns></returns>
        Task<ServiceResult<string>> GetLoginAddressAsync(Func<Task<ServiceResult<string>>> factory);

        /// <summary>
        /// 获取AccessToken
        /// </summary>
        /// <param name="code"></param>
        /// <param name="factory"></param>
        /// <returns></returns>
        Task<ServiceResult<string>> GetAccessTokenAsync(string code, Func<Task<ServiceResult<string>>> factory);

        /// <summary>
        /// 登录成功，生成Token
        /// </summary>
        /// <param name="access_token"></param>
        /// <param name="factory"></param>
        /// <returns></returns>
        Task<ServiceResult<string>> GenerateTokenAsync(string access_token, Func<Task<ServiceResult<string>>> factory);
    }
}
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是不是和IAuthorizeService代码很像，的确，我就是直接复制过来改的。

在AuthorizeCacheService中实现接口。

//AuthorizeCacheService.cs
using Meowv.Blog.ToolKits.Base;
using Meowv.Blog.ToolKits.Extensions;
using System;
using System.Threading.Tasks;
using static Meowv.Blog.Domain.Shared.MeowvBlogConsts;

namespace Meowv.Blog.Application.Caching.Authorize.Impl
{
    public class AuthorizeCacheService : CachingServiceBase, IAuthorizeCacheService
    {
        private const string KEY_GetLoginAddress = "Authorize:GetLoginAddress";

        private const string KEY_GetAccessToken = "Authorize:GetAccessToken-{0}";

        private const string KEY_GenerateToken = "Authorize:GenerateToken-{0}";

        /// <summary>
        /// 获取登录地址(GitHub)
        /// </summary>
        /// <param name="factory"></param>
        /// <returns></returns>
        public async Task<ServiceResult<string>> GetLoginAddressAsync(Func<Task<ServiceResult<string>>> factory)
        {
            return await Cache.GetOrAddAsync(KEY_GetLoginAddress, factory, CacheStrategy.NEVER);
        }

        /// <summary>
        /// 获取AccessToken
        /// </summary>
        /// <param name="code"></param>
        /// <param name="factory"></param>
        /// <returns></returns>
        public async Task<ServiceResult<string>> GetAccessTokenAsync(string code, Func<Task<ServiceResult<string>>> factory)
        {
            return await Cache.GetOrAddAsync(KEY_GetAccessToken.FormatWith(code), factory, CacheStrategy.FIVE_MINUTES);
        }

        /// <summary>
        /// 登录成功，生成Token
        /// </summary>
        /// <param name="access_token"></param>
        /// <param name="factory"></param>
        /// <returns></returns>
        public async Task<ServiceResult<string>> GenerateTokenAsync(string access_token, Func<Task<ServiceResult<string>>> factory)
        {
            return await Cache.GetOrAddAsync(KEY_GenerateToken.FormatWith(access_token), factory, CacheStrategy.ONE_HOURS);
        }
    }
}
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代码很简单，每个缓存都有固定KEY值，根据参数生成KEY，然后调用前面写的扩展方法，再给一个过期时间即可，可以看到KEY里面包含了冒号 :，这个冒号 : 可以起到类似于文件夹的操作，在界面化管理工具中可以很友好的查看。

这样我们的缓存就搞定了，然后在.Application层对应的Service中进行调用。代码如下：

//AuthorizeService.cs
using Meowv.Blog.Application.Caching.Authorize;
using Meowv.Blog.Domain.Configurations;
using Meowv.Blog.ToolKits.Base;
using Meowv.Blog.ToolKits.Extensions;
using Meowv.Blog.ToolKits.GitHub;
using Microsoft.IdentityModel.Tokens;
using System;
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Security.Claims;
using System.Threading.Tasks;

namespace Meowv.Blog.Application.Authorize.Impl
{
    public class AuthorizeService : ServiceBase, IAuthorizeService
    {
        private readonly IAuthorizeCacheService _authorizeCacheService;
        private readonly IHttpClientFactory _httpClient;

        public AuthorizeService(IAuthorizeCacheService authorizeCacheService,
                                IHttpClientFactory httpClient)
        {
            _authorizeCacheService = authorizeCacheService;
            _httpClient = httpClient;
        }

        /// <summary>
        /// 获取登录地址(GitHub)
        /// </summary>
        /// <returns></returns>
        public async Task<ServiceResult<string>> GetLoginAddressAsync()
        {
            return await _authorizeCacheService.GetLoginAddressAsync(async () =>
            {
                var result = new ServiceResult<string>();

                var request = new AuthorizeRequest();
                var address = string.Concat(new string[]
                {
                    GitHubConfig.API_Authorize,
                    "?client_id=", request.Client_ID,
                    "&scope=", request.Scope,
                    "&state=", request.State,
                    "&redirect_uri=", request.Redirect_Uri
                });

                result.IsSuccess(address);
                return await Task.FromResult(result);
            });
        }

        /// <summary>
        /// 获取AccessToken
        /// </summary>
        /// <param name="code"></param>
        /// <returns></returns>
        public async Task<ServiceResult<string>> GetAccessTokenAsync(string code)
        {
            var result = new ServiceResult<string>();

            if (string.IsNullOrEmpty(code))
            {
                result.IsFailed("code为空");
                return result;
            }

            return await _authorizeCacheService.GetAccessTokenAsync(code, async () =>
            {
                var request = new AccessTokenRequest();

                var content = new StringContent($"code={code}&client_id={request.Client_ID}&redirect_uri={request.Redirect_Uri}&client_secret={request.Client_Secret}");
                content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");

                using var client = _httpClient.CreateClient();
                var httpResponse = await client.PostAsync(GitHubConfig.API_AccessToken, content);

                var response = await httpResponse.Content.ReadAsStringAsync();

                if (response.StartsWith("access_token"))
                    result.IsSuccess(response.Split("=")[1].Split("&").First());
                else
                    result.IsFailed("code不正确");

                return result;
            });
        }

        /// <summary>
        /// 登录成功，生成Token
        /// </summary>
        /// <param name="access_token"></param>
        /// <returns></returns>
        public async Task<ServiceResult<string>> GenerateTokenAsync(string access_token)
        {
            var result = new ServiceResult<string>();

            if (string.IsNullOrEmpty(access_token))
            {
                result.IsFailed("access_token为空");
                return result;
            }

            return await _authorizeCacheService.GenerateTokenAsync(access_token, async () =>
            {
                var url = $"{GitHubConfig.API_User}?access_token={access_token}";
                using var client = _httpClient.CreateClient();
                client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.14 Safari/537.36 Edg/83.0.478.13");
                var httpResponse = await client.GetAsync(url);
                if (httpResponse.StatusCode != HttpStatusCode.OK)
                {
                    result.IsFailed("access_token不正确");
                    return result;
                }

                var content = await httpResponse.Content.ReadAsStringAsync();

                var user = content.FromJson<UserResponse>();
                if (user.IsNull())
                {
                    result.IsFailed("未获取到用户数据");
                    return result;
                }

                if (user.Id != GitHubConfig.UserId)
                {
                    result.IsFailed("当前账号未授权");
                    return result;
                }

                var claims = new[] {
                    new Claim(ClaimTypes.Name, user.Name),
                    new Claim(ClaimTypes.Email, user.Email),
                    new Claim(JwtRegisteredClaimNames.Exp, $"{new DateTimeOffset(DateTime.Now.AddMinutes(AppSettings.JWT.Expires)).ToUnixTimeSeconds()}"),
                    new Claim(JwtRegisteredClaimNames.Nbf, $"{new DateTimeOffset(DateTime.Now).ToUnixTimeSeconds()}")
                };

                var key = new SymmetricSecurityKey(AppSettings.JWT.SecurityKey.SerializeUtf8());
                var creds = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);

                var securityToken = new JwtSecurityToken(
                    issuer: AppSettings.JWT.Domain,
                    audience: AppSettings.JWT.Domain,
                    claims: claims,
                    expires: DateTime.Now.AddMinutes(AppSettings.JWT.Expires),
                    signingCredentials: creds);

                var token = new JwtSecurityTokenHandler().WriteToken(securityToken);

                result.IsSuccess(token);
                return await Task.FromResult(result);
            });
        }
    }
}
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直接return我们的缓存接口，当查询到Redis中存在KEY值的缓存就不会再走我们的具体的实现方法了。

注意注意，千万不要忘了在.Application层的模块类中添加依赖缓存模块MeowvBlogApplicationCachingModule，不然就会报错报错报错(我就是忘了添加...)

//MeowvBlogApplicationCachingModule.cs
using Meowv.Blog.Domain;
using Meowv.Blog.Domain.Configurations;
using Microsoft.Extensions.DependencyInjection;
using Volo.Abp.Caching;
using Volo.Abp.Modularity;

namespace Meowv.Blog.Application.Caching
{
    [DependsOn(
        typeof(AbpCachingModule),
        typeof(MeowvBlogDomainModule)
    )]
    public class MeowvBlogApplicationCachingModule : AbpModule
    {
        public override void ConfigureServices(ServiceConfigurationContext context)
        {
            context.Services.AddStackExchangeRedisCache(options =>
            {
                options.Configuration = AppSettings.Caching.RedisConnectionString;
            });
        }
    }
}
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此时项目的层级目录结构。

好的，编译运行项目，现在去调用接口看看效果，为了真实，这里我先将我redis缓存数据全部干掉。

访问接口，.../auth/url，成功返回数据，现在再去看看我们的redis。

成功将KEY为：Authorize:GetLoginAddress 添加进去了，这里直接使用RedisDesktopManager进行查看。

那么再次调用这个接口，只要没有过期，就会直接返回数据了，调试图如下：

可以看到，是可以直接取到缓存数据的，其他接口大家自己试试吧，一样的效果。

是不是很简单，用最少的代码集成Redis进行数据缓存，你学会了吗？😁😁😁

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