首先就是先要配置Memcached，这个回头再写。

https://zhidao.baidu.com/question/809745125827797732.html

https://www.cnblogs.com/XZhao/p/6821121.html

using Memcached.ClientLibrary;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace OAMS.Common
{
public class MemcacheHelper//声明一个类，里面放所用的方法之类的
{
private static readonly MemcachedClient mc = null;//MemcachedClient是添加的Memcached的dll里封装的
static MemcacheHelper()
{
//最好放在配置文件中
string[] serverlist = { "127.0.0.1:11211", "10.0.0.132:11211" };
//初始化池
SockIOPool pool = SockIOPool.GetInstance();
pool.SetServers(serverlist);

pool.InitConnections = 3;
pool.MinConnections = 3;
pool.MaxConnections = 5;

pool.SocketConnectTimeout = 1000;
pool.SocketTimeout = 3000;

pool.MaintenanceSleep = 30;
pool.Failover = true;

pool.Nagle = false;
pool.Initialize();

// 获得客户端实例
mc = new MemcachedClient();
mc.EnableCompression = false;
}

/// <summary>
/// 存储数据
/// </summary>
/// <param name="key"></param>
/// <param name="value"></param>
/// <returns></returns>
public static bool Set(string key, object value)
{
return mc.Set(key, value);
}
public static bool Set(string key, object value, DateTime time)
{
return mc.Set(key, value, time);
}
/// <summary>
/// 获取数据
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static object Get(string key)
{
return mc.Get(key);
}
/// <summary>
/// 删除
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public static bool Delete(string key)
{
if (mc.KeyExists(key))
{
return mc.Delete(key);

}
return false;

}
}
}

-------------------------------------------------------------------------

//将登录用户信息存储到Memcache中。
Common.MemcacheHelper.Set(sessionId, Common.SerializeHelper.SerializeToString(userInfo), DateTime.Now.AddMinutes(20));

//根据该值查Memcache.
object obj = Common.MemcacheHelper.Get(sessionId);

要在nuget里引用（安装） EnyimMemcached ,https://blog.csdn.net/ma_jiang/article/details/61419460