这几天在面试,这个关于Redis缓存的博客一直没空写,今天总算有点时间了。
从很久很久之前,我就一直想学Redis了,反正看到各大招聘网上都要求Redis,不学就太落后了。
一开始我是按微软官网文档那样配置的,然后发现这也太简单了,不止配置简单,连使用都这么简单,简单得有点过分。如下图所示,它是基于IDistributedCache接口注入的
这么简单,怎么玩,我连判断某个key值存不存在都没办法。
当然了。绝对不是这么简单的。更高级的用法如下,要引入Microsoft.Extensions.Caching.StackExchangeRedis包
ConnectionMultiplexer connection = ConnectionMultiplexer.Connect("127.0.0.1:6379"); IDatabase cache = connection.GetDatabase(0); cache.HashSet("key", "hashKey", "value"); cache.SetAdd("key2", "value");
那要怎么用在系统里呢,当然直接使用IDatabase也可以,但不够优雅,而且我还想通过配置文件,来决定是否启用Redis,如果不启用的话,就使用MemoryCache。非常好。想法有了。
先定义一个接口ICacheHelper,这是用来注入的接口,我暂时只定义了string类型跟hash类型的缓存方法
public interface ICacheHelper { bool Exists(string key); void Set(string key, T value); T Get (string key); void Delete(string key); void Expire(string key, DateTime dateTime); void Expire(string key, TimeSpan timeSpan); void HashSet(string key, string hashKey, object hashValue); T HashGet (string key, string hashKey); bool HashExists(string key, string hashKey); void HashDelete(string key, string hashKey); }
然后用Redis实现这个接口,RedisCacheHelper类
////// Redis助手 /// public class RedisCacheHelper : ICacheHelper { public IDatabase _cache; private ConnectionMultiplexer _connection; private readonly string _instance; public RedisCacheHelper(RedisCacheOptions options, int database = 0) { _connection = ConnectionMultiplexer.Connect(options.Configuration); _cache = _connection.GetDatabase(database); _instance = options.InstanceName; } public bool Exists(string key) { return _cache.KeyExists(_instance + key); } public void Set (string key, T value) { _cache.StringSet(_instance + key, CommonHelper.ObjectToJsonString(value)); } public T Get (string key) { return CommonHelper.JsonStringToObject (_cache.StringGet(_instance + key)); } public void Delete(string key) { _cache.KeyDelete(_instance + key); } public void Expire(string key, DateTime dateTime) { _cache.KeyExpire(_instance + key, dateTime); } public void Expire(string key, TimeSpan timeSpan) { _cache.KeyExpire(_instance + key, timeSpan); } public void HashSet(string key, string hashKey, object hashValue) { string value = CommonHelper.ObjectToJsonString(hashValue); _cache.HashSet(_instance + key, hashKey, value); } public T HashGet (string key, string hashKey) { var value = _cache.HashGet(_instance + key, hashKey); return CommonHelper.JsonStringToObject (value); } public object HashGet(string key, string hashKey, Type type) { var value = _cache.HashGet(_instance + key, hashKey); return CommonHelper.JsonStringToObject(value, type); } public bool HashExists(string key, string hashKey) { return _cache.HashExists(_instance + key, hashKey); } public void HashDelete(string key, string hashKey) { _cache.HashDelete(_instance + key, hashKey); } }
再用MemoryCache实现接口,MemoryCacheHelper类
////// 缓存助手 /// public class MemoryCacheHelper : ICacheHelper { private readonly IMemoryCache _cache; public MemoryCacheHelper(IMemoryCache cache) { _cache = cache; } public bool Exists(string key) { return _cache.TryGetValue(key, out _); } public T Get (string key) { return _cache.Get (key); } public void Delete(string key) { _cache.Remove(key); } public void Set (string key, T value) { _cache.Set(key, value); } public void Expire(string key, DateTime dateTime) { var value = _cache.Get(key); _cache.Set(key, value, dateTime); } public void Expire(string key, TimeSpan timeSpan) { var value = _cache.Get(key); _cache.Set(key, value, timeSpan); } public void HashSet(string key, string hashKey, object hashValue) { var hash = _cache.Get string, object>>(key); if (hash.ContainsKey(hashKey)) { hash[key] = hashValue; } else { hash.Add(hashKey, hashValue); } _cache.Set string, object>>(key, hash); } public T HashGet (string key, string hashKey) { var hash = _cache.Get string, object>>(key); if (hash.ContainsKey(hashKey)) { return (T)hash[hashKey]; } else { return default(T); } } public bool HashExists(string key, string hashKey) { var hash = _cache.Get string, object>>(key); return hash.ContainsKey(hashKey); } public void HashDelete(string key, string hashKey) { var hash = _cache.Get string, object>>(key); if (hash.ContainsKey(hashKey)) { hash.Remove(hashKey); } } }
实现类都有了,那现在就来实现根据配置值来决定是否使用Redis还是MemoryCache,先在appsettings.json里添加这个配置值,当Enable为false时,就不启用Redis,使用MemoryCache,Connection是Redis的连接字符串,InstanceName是缓存的前缀,Database是使用哪个数据库
"Redis": { "Enable": true, "Connection": "127.0.0.1:6379", "InstanceName": "LessSharp:", "Database": 0 }
再定义一个选项类 RedisOption
public class RedisOption { public bool Enable { get; set; } public string Connection { get; set; } public string InstanceName { get; set; } public int Database { get; set; } }
然后在Startup.cs类里的ConfigureServices里根据配置值进行注入
var RedisConfiguration = Configuration.GetSection("Redis"); services.Configure(RedisConfiguration); RedisOption redisOption = RedisConfiguration.Get (); if (redisOption != null && redisOption.Enable) { var options = new RedisCacheOptions { InstanceName = redisOption.InstanceName, Configuration = redisOption.Connection }; var redis = new RedisCacheHelper(options, redisOption.Database); services.AddSingleton(redis); services.AddSingleton (redis); } else { services.AddMemoryCache(); services.AddScoped (); }
OK,测试后完美