.net core 实现默认图片

男娘i 2022-09-17 03:04 112阅读 0赞

web 上 如果图片不存在 一般是打xx 这时候 一般都是会设置默认的图片 代替 现在用中间件的方式实现统一设置 一次设置 全部作用

.net core 实现默认图片

Startup 文件

app.UseDefaultImage(defaultImagePath: Configuration.GetSection("defaultImagePath").Value);

新建类

using Microsoft.AspNetCore.Builder;
    using Microsoft.AspNetCore.Http;
    using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Threading.Tasks;
     
    
    namespace conan.Saas.Framework.Middlewares
    {
        public class DefaultImageMiddleware
        {
            private readonly RequestDelegate _next;
     
            public static string DefaultImagePath { get; set; }
    
            public DefaultImageMiddleware(RequestDelegate next)
            {
                this._next = next;
            }
    
     
            public async Task Invoke(HttpContext context)
            {
                await _next(context);
    
                if (context.Response.StatusCode == 404)
                {
                    var contentType = context.Request.Headers["accept"].ToString().ToLower();
    
                    if (contentType.StartsWith("image"))
                    {
                        await SetDefaultImage(context);
                    }
                }
            }
    
     
            private async Task SetDefaultImage(HttpContext context)
            {
                try
                {
                    string path = Path.Combine(Directory.GetCurrentDirectory(), DefaultImagePath);
    
                     FileStream fs = File.OpenRead(path);
                    byte[] bytes = new byte[fs.Length];
                    await fs.ReadAsync(bytes, 0, bytes.Length);
                    //this header is use for browser cache, format like: "Mon, 15 May 2017 07:03:37 GMT".
                    //context.Response.Headers.Append("Last-Modified", $"{File.GetLastWriteTimeUtc(path).ToString("ddd, dd MMM yyyy HH:mm:ss")} GMT");
    
                     await context.Response.Body.WriteAsync(bytes, 0, bytes.Length);
                }
                catch (Exception ex)
                {
                    await context.Response.WriteAsync(ex.Message);
                }
            }
        }
    
     
        public static class DefaultImageMiddlewareExtensions
        {
    
            public static IApplicationBuilder UseDefaultImage(this IApplicationBuilder app, string defaultImagePath)
            {
                DefaultImageMiddleware.DefaultImagePath = defaultImagePath;
    
                 return app.UseMiddleware<DefaultImageMiddleware>();
            }
        }
    }

appsettings.json 添加路径

"defaultImagePath": "wwwroot\\DefaultImage.png",

最后 在 wwwroot 放张 DefaultImage.png图片 即可

https://www.cnblogs.com/lyl6796910/p/7660076.html