如何使 IMemoryCache 在所有控制器中可用？

Question

我已经学习了这个教程https://docs.microsoft.com/en-us/aspnet/core/performance/caching/memory?view=aspnetcore-2.2

它正在使用依赖注入使 IMemoryCache 仅在特定控制器中可用，例如

public class TController : ControllerBase
{
    public IConfiguration Configuration { get; }

    private IMemoryCache _cache;

    public TController(IConfiguration configuration, IMemoryCache memoryCache)
    {
        Configuration = configuration;
        _cache = memoryCache;
    }

    public IActionResult GetAccessToken()
    {

        string key ="IDGKey";
        string obj;
        if (!cache.TryGetValue<string>(key, out obj))
        {
            obj = DateTime.Now.ToString();
            _cache.Set<string>(key, obj);
        }
        return obj;

    }
}

现在，如果我尝试访问同一命名空间或不同控制器中的 _cache 值

public class RController : ControllerBase
{
    public IActionResult R()
    {
        var cb = _cache.Get("IDGKey");
        return Ok(cb);
    }
}

出现以下错误 -

The name '_cache' does not exist in the current context (CS0103)

如何让它对所有控制器都可用_cache？

Answer 1

首先你需要定义一些使用IMemoryCache

的基础控制器class

public abstract class MyBaseController : ControllerBase
{
    public IConfiguration Configuration { get; }
    protected IMemoryCache _memoryCache;

    public MyBaseController(IConfiguration configuration, IMemoryCache memoryCache)
    {
        Configuration = configuration;
        _memoryCache = memoryCache;
    }
}

然后从它继承你的控制器并且不要忘记调用基础 class 构造函数来实例化 IMemoryCache

public class MyController : MyBaseController
{
    public MyController(IConfiguration configuration, IMemoryCache memoryCache): base(configuration, memoryCache)
    {
    }

    public IActionResult Action()
    {
        var value = _memoryCache.Get("some key");
        return Ok();
    }
}