69 lines
2.4 KiB
C#
69 lines
2.4 KiB
C#
using Microsoft.AspNetCore.Builder;
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using Microsoft.AspNetCore.Http;
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using System;
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using System.IO;
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using System.Threading.Tasks;
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namespace Nirvana.Common.Middleware
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{
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/// <summary>
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/// 默认图片中间件,使用方法app.UseDefaultImage(defaultImagePath: Configuration.GetSection("defaultImagePath").Value);
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/// </summary>
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public class DefaultImageMiddleware
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{
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private readonly RequestDelegate _next;
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public static string DefaultImagePath { get; set; }
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public DefaultImageMiddleware(RequestDelegate next)
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{
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this._next = next;
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}
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public async Task InvokeAsync(HttpContext context)
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{
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await _next(context);
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if (context.Response.StatusCode == 404)
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{
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var contentType = context.Request.Headers["accept"].ToString().ToLower();
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if (contentType.StartsWith("image"))
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{
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await SetDefaultImageAsync(context);
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}
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}
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}
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/// <summary>
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/// 设置默认图片
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/// </summary>
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/// <param name="context"></param>
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private async Task SetDefaultImageAsync(HttpContext context)
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{
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try
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{
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string path = Path.Combine(Directory.GetCurrentDirectory(), DefaultImagePath);
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FileStream fs = System.IO.File.OpenRead(path);
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byte[] bytes = new byte[fs.Length];
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await fs.ReadAsync(bytes, 0, bytes.Length);
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//this header is use for browser cache, format like: "Mon, 15 May 2017 07:03:37 GMT".
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//context.Response.Headers.Append("Last-Modified", $"{File.GetLastWriteTimeUtc(path).ToString("ddd, dd MMM yyyy HH:mm:ss")} GMT");
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await context.Response.Body.WriteAsync(bytes, 0, bytes.Length);
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}
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catch (Exception ex)
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{
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await context.Response.WriteAsync(ex.Message);
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}
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}
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}
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/// <summary>
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/// 默认图片中间件扩展
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/// </summary>
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public static class DefaultImageMiddlewareExtensions
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{
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public static IApplicationBuilder UseDefaultImage(this IApplicationBuilder app, string defaultImagePath)
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{
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DefaultImageMiddleware.DefaultImagePath = defaultImagePath;
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app.UseMiddleware<DefaultImageMiddleware>();
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return app;
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}
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}
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}
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