asp.net mvc json数据缓存

一些虚拟主机资源给的少, 如果直接用框架缓存, 估计内存就爆了吧, 如果不用缓存, 虚拟主机自带的数据库也是限制资源的, 访问多了就直接给timeout了,

用json文件形式缓存查询出来的数据, 虽然占用一些空间, 使用一些IO, 也是比查询数据库快的, 至少不会timeout了, 不过会占用一些空间, 可是现在虚拟主机空间都不小了, 不差这一点了哈哈,

key直接作为文件名了,扩展名乱写的(*.cache)

超时时间比较用的是DateTime.Ticks, 单位是微妙, 看下面的换算吧, 在AppSetting中增加一个cache_time节点, 单位是秒

<appSettings>
    <!-- 缓存时间, 单位(秒) -->
    <add key="cache_time" value="120" />
</appSettings>

 

public class JCache
{
    public static string DirPath { get; set; }
    private static string SplitChar = "!/~/#!";
    /// <summary>
    /// 缓存时间(秒)
    /// </summary>
    private static long CacheTime
    {
        get
        {
            return Convert.ToInt64(ConfigurationManager.AppSettings["cache_time"]) * 10000000;
        }
    }
    public static T Get<T>(string key)
        where T : class, new()
    {
        var filename = Path.Combine(DirPath, key + ".cache");
        if(!Directory.Exists(DirPath))
        {
            Directory.CreateDirectory(DirPath);
        }
        if (!File.Exists(filename))
            return null;
        var fileContent = string.Empty;// File.ReadAllText(filename, System.Text.Encoding.UTF8);
        using (var fs = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
        {
            fileContent = new StreamReader(fs, System.Text.Encoding.UTF8).ReadToEnd();
        }
        if (string.IsNullOrEmpty(fileContent))
            return null;
        if (!fileContent.Contains(SplitChar))
            return null;
        var arr = fileContent.Split(new string[] { SplitChar }, StringSplitOptions.RemoveEmptyEntries);
        try
        {
            var d = Convert.ToInt64(arr[0]);
            if (DateTime.Now.Ticks - d > CacheTime)
                return null;

            var res = JsonConvert.DeserializeObject<T>(arr[1]);
            return res;
        }
        catch (Exception ex)
        {
            return null;
        }
    }

    public static void Set(string key, object obj)
    {
        if (!Directory.Exists(DirPath))
        {
            Directory.CreateDirectory(DirPath);
        }
        var filename = Path.Combine(DirPath, key + ".cache");
        var d = DateTime.Now.Ticks.ToString();
        if (obj == null)
            return;
        var json = JsonConvert.SerializeObject(obj);
        var fileContent = string.Concat(d, SplitChar, json);
        try
        {
            using (var fs = new FileStream(filename, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite))
            {
                new StreamWriter(fs, System.Text.Encoding.UTF8).Write(fileContent);
            }
            //File.WriteAllText(filename, fileContent);
        }
        catch (Exception ex)
        {
            var xx = 1;
        }
    }
}

 使用方法

var cahceKey = "xxxkey";
var cache = JCache.Get<T>(cacheKey);

var model = new T();
if(cache == null){
     JCache.Set<T>(cacheKey, 查询出来的数据);
}else{
    model = cache;
}