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
)
