using System;
using System.Runtime.Caching;
class Program
{
    private static readonly MemoryCache Cache = MemoryCache.Default;
    static void Main()
    {
        // 添加緩存項，設置5分鐘絕對過期時間
        var policy = new CacheItemPolicy
        {
            AbsoluteExpiration = DateTimeOffset.Now.AddMinutes(5)
        };
        Cache.Add("my_cache_key", "緩存的值", policy);
        // 獲取緩存值
        if (Cache.Contains("my_cache_key"))
        {
            var value = Cache.Get("my_cache_key");
            Console.WriteLine($"從緩存獲取: {value}");
        }
        // 移除緩存項
        Cache.Remove("my_cache_key");
    }
}

public class DataService
{
    private static readonly MemoryCache Cache = MemoryCache.Default;
    public string GetExpensiveData(string key)
    {
        if (Cache.Contains(key))
        {
            return Cache.Get(key) as string;
        }
        // 模擬耗時操作
        var data = ExpensiveDatabaseCall(key);
        var policy = new CacheItemPolicy
        {
            SlidingExpiration = TimeSpan.FromMinutes(10),
            RemovedCallback = arguments =>
            {
                Console.WriteLine($"緩存項 {arguments.CacheItem.Key} 被移除，原因: {arguments.RemovedReason}");
            }
        };
        Cache.Add(key, data, policy);
        return data;
    }
    private string ExpensiveDatabaseCall(string key)
    {
        // 模擬數(shù)據(jù)庫查詢
        Thread.Sleep(2000);
        return $"數(shù)據(jù)庫查詢結(jié)果 for {key}";
    }
}

// 創(chuàng)建文件依賴的緩存項
var filePaths = new List<string> { @"C:\data\config.xml" };
var policy = new CacheItemPolicy
{
    ChangeMonitors = { new HostFileChangeMonitor(filePaths) }
};
Cache.Add("config_data", LoadConfig(), policy);

// 獲取當前緩存統(tǒng)計信息
var cacheStats = Cache.GetCount();
Console.WriteLine($"當前緩存項數(shù)量: {cacheStats}");
// 設置內(nèi)存限制（單位：字節(jié)）
var cacheSettings = new NameValueCollection
{
    { "cacheMemoryLimitMegabytes", "100" }, // 100MB
    { "physicalMemoryLimitPercentage", "50" } // 物理內(nèi)存50%
};
var customCache = new MemoryCache("CustomCache", cacheSettings);

// 創(chuàng)建命名緩存實例
var userCache = new MemoryCache("UserCache");
var productCache = new MemoryCache("ProductCache");
// 在不同緩存中存儲數(shù)據(jù)
userCache.Add("user_123", GetUser(123), policy);
productCache.Add("product_456", GetProduct(456), policy);