Asp.Net Core 自定义设置Http缓存处理

一、使用中间件拦截请求自定义输出文件

输出前自定义指定响应头

    public class OuterImgMiddleware
    {
        public static string RootPath { get; set; } //配置文件读取绝对位置
        private readonly RequestDelegate _next;
        public OuterImgMiddleware(RequestDelegate next, IHostingEnvironment env)
        {
            _next = next;
        }
        public async Task Invoke(HttpContext context)
        {
            var path = context.Request.Path.ToString();
            var headersDictionary = context.Request.Headers;

            if (context.Request.Method == "GET")
                if (!string.IsNullOrEmpty(path) && path.Contains("/upload/logo"))
                {
                    var unauthorizedImagePath = RootPath + path;
                    context.Response.ContentType = "image/jpeg";
                    context.Response.Headers["Cache-Control"] = "public"; //指定客户端，服务器都处理缓存
                    int length = path.LastIndexOf(".") - path.LastIndexOf("/") - 1;
                    context.Response.Headers["Etag"] = path.Substring(path.LastIndexOf("/") + 1, length);
                    context.Response.Headers["Last-Modified"] = new DateTime(2018).ToString("r");

                    FileInfo file = new FileInfo(unauthorizedImagePath);
                    context.Response.Headers["Content-Length"] = file.Length.ToString();
                    context.Response.Headers["Accept-Ranges"] = "bytes";

                    //如果Transfer-Encoding =chunked 没有指定的话，SendFile 前台解析事变
                    //指定Content-Length 可以是 chunked 分块实效
                    //context.Response.Headers["Transfer-Encoding"] = "";

                    //Http 1.0 是使用Expires 属性
                    //context.Response.Headers["Expires"] = DateTime.Now.AddMonths(1).ToString("r");
                    await context.Response.SendFileAsync(unauthorizedImagePath);

                    return;
                }

            await _next(context);
        }
    }

    public static class MvcExtensions
    {
        public static IApplicationBuilder UseOutImg(this IApplicationBuilder builder)
        {
            return builder.UseMiddleware<OuterImgMiddleware>();
        }
    }