.net core 实现默认图片

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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>();
}
}
}