缓存可以通过减少生成内容所需的工作，显著提高应用的性能和可伸缩性。 缓存最适用于不常更改且生成成本很高的数据。 缓存生成的数据副本可以比从源中更快地返回。 应该以从不依赖于缓存数据的方式编写和测试应用。ASP.NET Core 支持多个不同的缓存。
本文主要介绍三种缓存方式
| 缓存类别 | Nuget |
|---|---|
| Memory内存 | Microsoft.Extensions.Caching.Memory |
| SqlServer | Microsoft.Extensions.Caching.SqlServer |
| Redis | Microsoft.Extensions.Caching.StackExchangeRedis |
添加缓存服务
Memory
//分布式
services.AddDistributedMemoryCache();
//非分布式
//services.AddMemoryCache();
Redis
services.AddStackExchangeRedisCache(options =>
{
options.Configuration = "192.168.1.105:6379,password=1qaz@WSX3edc$RFV,ssl=False,abortConnect=False";
options.InstanceName = "App-Instance-Keys";
});
services.AddStackExchangeRedisCache(options =>
{
options.ConfigurationOptions = new StackExchange.Redis.ConfigurationOptions()
{
Password = "1qaz@WSX3edc$RFV",
ConnectTimeout = 5000,//设置建立连接到Redis服务器的超时时间为5000毫秒
SyncTimeout = 5000,//设置对Redis服务器进行同步操作的超时时间为5000毫秒
ResponseTimeout = 5000,//设置对Redis服务器进行操作的响应超时时间为5000毫秒
Ssl = false,//设置启用SSL安全加密传输Redis数据
//SslHost=""
//SslProtocols = System.Security.Authentication.SslProtocols.Tls//还可以通过SslProtocols属性指定SSL具体用到的是什么协议，不过这个属性不是必须的
};
options.ConfigurationOptions.EndPoints.Add("192.168.1.105:6379");
options.InstanceName = "App-Instance-Keys";
});
SqlServer
services.AddDistributedSqlServerCache(options =>
{
options.SchemaName = "dbo";
options.ConnectionString = Configuration["SqlServerConnection"];
//会创建一个外部表
options.TableName = "AppCache";
//默认缓存时间
options.DefaultSlidingExpiration = TimeSpan.FromMinutes(20);
//过时自动删除
options.ExpiredItemsDeletionInterval = TimeSpan.FromMinutes(30);
});
使用缓存
DistributedCacheEntryOptions是设置缓存时间的配置类
//设置十分钟后过期
new DistributedCacheEntryOptions().SetAbsoluteExpiration(TimeSpan.FromMinutes(10));
//设置以当前时间为例，十分钟后过期
new DistributedCacheEntryOptions().SetAbsoluteExpiration(DateTimeOffset.Now.AddMinutes(10));
new DistributedCacheEntryOptions {
//设置未来某一个时间过期
AbsoluteExpiration = DateTimeOffset.Now.AddMinutes(10),
//设置以当前时间为例，过过长时间过期，案例为10分钟
//AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(10)
};
设置缓存
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Caching.Distributed;
using System;
using System.Threading.Tasks;
namespace MicrosoftCache.Controllers
{
[ApiController]
[Route("[controller]")]
public class RedisController : ControllerBase
{
private readonly IDistributedCache _distributedCache;
public RedisController(IDistributedCache distributedCache)
{
_distributedCache = distributedCache;
}
[HttpGet]
public async Task Get()
{
//设置十分钟后过期
var dco= new DistributedCacheEntryOptions().SetAbsoluteExpiration(TimeSpan.FromMinutes(10));
string key = "demokey";
//添加/修改缓存时间
_distributedCache.SetString(key, "123456", dco);
//异步缓存
await _distributedCache.SetStringAsync("demokeyAsync", "123456", dco);
//获取缓存数据
var getvlaue = _distributedCache.GetString(key);
//刷新
_distributedCache.Refresh(key);
//删除
_distributedCache.Remove(key);
object value = new { id=1,user = "zs" };
var stringObject = System.Text.Json.JsonSerializer.Serialize(value, new System.Text.Json.JsonSerializerOptions
{
//.Net6+
ReferenceHandler = System.Text.Json.Serialization.ReferenceHandler.IgnoreCycles
});
var bytesObject = System.Text.Encoding.UTF8.GetBytes(stringObject);//将Json字符串通过UTF-8编码，序列化为字节数组
//设置byte 缓存
_distributedCache.Set(key, bytesObject, dco);
//刷新Redis
_distributedCache.Refresh(key);
//获取byte 缓存数据
var bytesGetObject = _distributedCache.Get(key);
var stringGetObject = System.Text.Encoding.UTF8.GetString(bytesGetObject);//通过UTF-8编码，将字节数组反序列化为Json字符串
var bytevlaue = System.Text.Json.JsonSerializer.Deserialize<object>(stringGetObject);
}
}
}
缓存帮助类
using Microsoft.Extensions.Caching.Distributed;
using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;
namespace MicrosoftCache
{
/// <summary>
/// Cache缓存操作类
/// </summary>
public class CacheHelper
{
protected IDistributedCache cache;
/// <summary>
/// 通过IDistributedCache来构造RedisCache缓存操作类
/// </summary>
/// <param name="cache">IDistributedCache对象</param>
public CacheHelper(IDistributedCache cache)
{
this.cache = cache;
}
/// <summary>
/// 添加或更改Redis的键值，并设置缓存的过期策略
/// </summary>
/// <param name="key">缓存键</param>
/// <param name="value">缓存值</param>
/// <param name="distributedCacheEntryOptions">设置Redis缓存的过期策略</param>
public void Set(string key, object value, DistributedCacheEntryOptions distributedCacheEntryOptions)
{
var stringObject = JsonSerializer.Serialize(value, new JsonSerializerOptions
{
ReferenceHandler = ReferenceHandler.IgnoreCycles
});
var bytesObject = Encoding.UTF8.GetBytes(stringObject);//将Json字符串通过UTF-8编码，序列化为字节数组
cache.Set(key, bytesObject, distributedCacheEntryOptions);
Refresh(key);//刷新Redis
}
/// <summary>
/// 查询键值是否在Redis中存在
/// </summary>
/// <param name="key">缓存键</param>
/// <returns>true：存在，false：不存在</returns>
public bool Exist(string key) => cache.Get(key) != null;
/// <summary>
/// Redis中获取键值
/// </summary>
/// <typeparam name="T">缓存的类型</typeparam>
/// <param name="key">缓存键</param>
/// <param name="isExisted">是否获取到键值，true：获取到了，false：键值不存在</param>
/// <returns>缓存的对象</returns>
public T Get<T>(string key, out bool isExisted)
{
var bytesObject = cache.Get(key);//从Redis中获取键值key的字节数组，如果没获取到，那么会返回null
if (bytesObject == null)
{
isExisted = false;
return default(T);
}
var stringObject = Encoding.UTF8.GetString(bytesObject);//通过UTF-8编码，将字节数组反序列化为Json字符串
isExisted = true;
return JsonSerializer.Deserialize<T>(stringObject);
}
/// <summary>
/// Redis中删除键值
/// </summary>
/// <param name="key">缓存键</param>
public void Remove(string key)=> cache.Remove(key);
/// <summary>
/// 从Redis中刷新键值
/// </summary>
/// <param name="key">缓存键</param>
public void Refresh(string key)=> cache.Refresh(key);
}
}