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>(key); if (hash.ContainsKey(hashKey))
{
hash[key]=hashValue;
} else {
hash.Add(hashKey, hashValue);
}
_cache.Set>(key, hash);
} public T HashGet(string key, string hashKey)
{ var hash=_cache.Get>(key); if (hash.ContainsKey(hashKey))
{ return (T)hash[hashKey];
} else { return default(T);
}
} public bool HashExists(string key, string hashKey)
{ var hash=_cache.Get>(key); return hash.ContainsKey(hashKey);
} public void HashDelete(string key, string hashKey)
{ var hash=_cache.Get>(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