.Net Core MemoryCache-权限菜单缓存
标签：实现 remove pack name 举例 扩展 help 框架 产品
前提：在框架设计中，因为权限菜单访问比较频繁，相对稳定，且数据体积较小，通过缓存来提升性能，提升获取数据的效率。
1.ICache封装
缓存接口，实现对缓存增删改查的封装
1 public interface ICache
2 {
3 ///
4 /// 读取缓存
5 ///
6 ///
7 ///
8 ///
9 T Get(string key);
10 ///
11 /// 设置缓存
12 ///
13 ///
14 ///
15 ///
16 void Add(string key, T data, ObsloteType obsloteType = default, int cachetime = 30);
17 ///
18 /// 是否包含
19 ///
20 ///
21 ///
22 bool Contains(string key);
23 ///
24 /// 清除缓存
25 ///
26 ///
27 bool Remove(string key);
28 ///
29 /// 更新缓存
30 ///
31 ///
32 ///
33 bool Upate(string key,T data, ObsloteType obsloteType = default, int cacheMin = 30);
34
35 }
枚举类 ObsloteType
1 ///
2 /// Cache策略类型 永久/绝对过期/滑动过期
3 ///
4 public enum ObsloteType
5 {
6 ///
7 /// 永久
8 ///
9 Never,
10 ///
11 /// 绝对过期
12 ///
13 Absolutely,
14 ///
15 /// 滑动过期 如果期间查询或更新，就再次延长
16 ///
17 Relative
18 }
2.MemoryCache使用
引用Nuget包 Install-Package Microsoft.Extensions.Caching.Memory
（1）缓存设置
在Startup.cs的ConfigureServices中添加
1 services.AddMemoryCache(options =>
2 {
3 //最大缓存空间大小限制为 1024
4 options.SizeLimit = 1024;
5 //缓存策略设置为缓存压缩比为 2%
6 options.CompactionPercentage = 0.02d;
7 //每 5 分钟进行一次过期缓存的扫描
8 options.ExpirationScanFrequency = TimeSpan.FromMinutes(5);
9 });
（2）注入并使用
1 private readonly IMemoryCache _memoryCache;
2 public HomeController(IMemoryCache memoryCache)
3 {
4 _memoryCache = memoryCache;
5 }
缓存的操作增删改查
(2-1)Set
public IActionResult Index()
{
_memoryCache.Setstring>("timestamp", DateTime.Now.ToString());
return View();
}
(2-2)Get
public IActionResult Show()
{
string timestamp = _memoryCache.Getstring>("timestamp");
return View("Show",timestamp);
}
(2-3)TryGetValue检查特定值
if (!_memoryCache.TryGetValuestring>
("timestamp", out string timestamp))
{
_memoryCache.Setstring>("timestamp", DateTime.Now.ToString());
}
（2-4）GetOrCreate() 不存在新增，存在获取
public IActionResult Show()
{
string timestamp = cache.GetOrCreatestring>
("timestamp", entry => {
return DateTime.Now.ToString(); });
return View("Show",timestamp);
}
缓存的过期时间策略： 永久|绝对过期|滚动过期
（2-5）缓存时间配置
绝对过期：AbsoluteExpiration 在指定的日期和时间点被移除
滚动过期： SlidingExpiration 在一段时间内处于空闲状态会被移除
1 MemoryCacheEntryOptions options = new MemoryCacheEntryOptions();
2 options.AbsoluteExpiration = DateTime.Now.AddMinutes(1);
3 options.SlidingExpiration = TimeSpan.FromMinutes(1);
4 _memoryCache.Setstring>("timestamp", DateTime.Now.ToString(), options);
2.扩展MemoryEetensions
（1）新建“MemoryCacheExtensions”实现ICache的接口
1 public class MemoryCacheExtensions:ICache
2 {
3 private readonly IMemoryCache _cache;
4 ///
5 /// 缓存配置项
6 ///
7 private readonly MemoryCacheEntryOptions _memoryCacheEntryOptions;
8 //构造器注入
9 public MemoryCacheExtensions(IMemoryCache cache)
10 {
11 //单项缓存设置项
12 _memoryCacheEntryOptions = new MemoryCacheEntryOptions()
13 {
14 Priority = CacheItemPriority.Low,
15 //缓存大小占1份
16 Size = 1
17 };
18 _cache = cache;
19 }
20 ///
21 /// 添加
22 ///
23 ///
24 ///
25 ///
26 ///
27 public void Add(string key, T data, ObsloteType obsloteType = default, int cacheMin = 30)
28 {
29 if (obsloteType == ObsloteType.Absolutely)
30 {
31 _memoryCacheEntryOptions.AbsoluteExpiration = DateTime.Now.AddMinutes(cacheMin);
32 }
33 if (obsloteType == ObsloteType.Relative)
34 {
35 _memoryCacheEntryOptions.SlidingExpiration = TimeSpan.FromMinutes(cacheMin);
36 }
37 if (Contains(key))
38 {
39 Upate(key, data, obsloteType);
40 }
41 else
42 {
43 _cache.Set(key, data, _memoryCacheEntryOptions);
44 }
45
46 }
47 ///
48 /// 是否存在
49 ///
50 ///
51 ///
52 public bool Contains(string key)
53 {
54 object RetValue;
55 return _cache.TryGetValue(key, out RetValue);
56 }
57 public T Get(string key)
58 {
59 return _cache.Get(key);
60 }
61
62 public bool Remove(string key)
63 {
64 bool ReturnBool = true;
65 if (!Contains(key))
66 {
67 ReturnBool = false;
68 }
69 else {
70 _cache.Remove(key);
71 }
72
73 return ReturnBool;
74 }
75 public bool Upate(string key,T data, ObsloteType obsloteType, int cacheMin = 30)
76 {
77 bool ReturnBool = true;
78 if (!Contains(key))
79 {
80 ReturnBool = false;
81 }
82 else
83 {
84 _cache.Remove(key);
85 Add(key, data, obsloteType, cacheMin);
86 }
87 return ReturnBool;
88
89 }
90 }
其中“MemoryCacheEntryOptions”缓存项设置，可以设置Priority（优先级），Size（缓存大小），缓存时间的配置（参见2-5）
（2）在Startup中注入扩展类
services.AddScoped(typeof(MemoryCacheExtensions));
3.MemoryCacheExtensions使用，对权限菜单缓存读取
1 private readonly Frame_RelationsService _service;
2 private readonly MemoryCacheExtensions _memoryCacheExtensions;
3 public FrameRelationsController(Frame_RelationsService service, MemoryCacheExtensions memoryCacheExtensions)
4 {
5 _service = service;
6 _memoryCacheExtensions = memoryCacheExtensions;
7 }
8
9 [AllowAnonymous]
10 public string LoadRoleMenu( )
11 {
12 PageResponse resp = new PageResponse();
13 string KeyName = "Menu_" + CurrentUser.ID;
14 //第一次加载 判断是否有Key为"Keyname"的缓存
15 if (_memoryCacheExtensions.Contains(KeyName))
16 {
17 resp.Message = _memoryCacheExtensions.Get(KeyName);
18 }
19 else
20 {
21 //返回菜单权限的信息
22 resp.Message = _service.LoadRoleMenu(CurrentUser.RoleID);
23 _memoryCacheExtensions.Add(KeyName, resp.Message);
24 }
25 return JsonHelper.Instance.Serialize(Newtonsoft.Json.Linq.JArray.Parse(resp.Message));
26 }
总结：适合缓存的特点：访问频繁，耗时耗资源，相对稳定，体积不大。
举例：字典/省市区/配置文件/公告信息/部门/权限/热搜/产品列表/商品评论
.Net Core MemoryCache-权限菜单缓存
标签：实现 remove pack name 举例 扩展 help 框架 产品
原文地址：https://www.cnblogs.com/ywkcode/p/12283855.html
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