第十一篇 自定义一个缓存类（甚用~）

 1 //自定义缓存类
 2    public class CacheHelper<T>    where T:class
 3     {
 4         private class Entity
 5         {
 6             public T Value{get;set;}
 7             public DateTime Expiretime { get; set; }
 8         }
 9         private static readonly Dictionary<string, Entity> Dic=new Dictionary<string,Entity>();
10 
11         public T this[string key]
12         {
13             get
14             {
15                 if (!Dic.Keys.Contains(key)) return null;
16                 var data = Dic[key];
17                 if (data.Expiretime >= DateTime.Now)
18                 {
19                     return data.Value;
20                 }
21                 Remove(key);
22                 return null;
23             }
24         }
25 
26         public void Add(string key, T value, int min)
27         {
28              if( key == null ) {
29                  throw new Exception("键值不能为空");
30             }
31              if (Dic.Keys.Contains(key))
32                  throw new Exception("键值已经存在");
33 
34              if (min <= 0) throw new Exception("过期时间不能小于0或等于0");
35 
36              var entity = new Entity {Value = value, Expiretime = DateTime.Now.AddSeconds(min)};
37             Dic.Add(key, entity);
38         }
39 
40         public void Update(string key, T value, int min)
41         {
42             if (key == null)
43             {
44                 throw new Exception("键值不能为空");
45             }
46             if (min <= 0) throw new Exception("过期时间不能小于0或等于0");
47 
48             var entity = new Entity {Value = value, Expiretime = DateTime.Now.AddSeconds(min)};
49             Dic[key] = entity;
50         }
51 
52         public void Remove(string key)
53         {
54             if (key == null)
55             {
56                 throw new Exception("键值不能为空");
57             }
58             if (!Dic.Keys.Contains(key))
59                 throw new Exception("键值不存在");
60             Dic.Remove(key);
61         }
62 
63     }