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ASP.NET Core 中实现 Markdown 渲染中间件

news 2025/5/10 10:26:04

文章目录

前言
一、核心功能
二、实现步骤
- 1）安装依赖包
- 2）创建中间件类
- 3）中间件扩展方法
- 4）在Program.cs配置
- 5）模板文件示例
- 6）*.md文件示例
- 7）缓存优化
- 8）使用示例
三、注意事项
总结

前言

Markdown 内容的动态渲染，适用于文档系统、博客引擎等场景。

一、核心功能

自动识别请求路径：将 .md 或 .markdown 结尾的请求视为 Markdown 文件请求。
实时转换：将 Markdown 内容转换为 HTML。
支持模板嵌入：将渲染后的 HTML 嵌入统一布局模板。
异常处理：处理文件不存在或转换错误。

二、实现步骤

1）安装依赖包

使用 NuGet 安装 Markdown 解析库（推荐 Markdig）：
```
Install-Package Markdig
```

2）创建中间件类

MarkdownRenderingMiddleware.cs

using Microsoft.Extensions.FileProviders;namespace MarkDownMiddleware.Middleware
{public class MarkdownRenderingMiddleware{private readonly RequestDelegate next;private readonly IFileProvider _fileProvider;private readonly string _template;public MarkdownRenderingMiddleware(RequestDelegate next, IFileProvider fileProvider, string template=null){this.next = next;_fileProvider = fileProvider;_template = template ?? "<html><body>{0}</body></html>";}public async Task InvokeAsync(HttpContext context){var path=context.Request.Path.Value;if (!path.EndsWith(".md")&&!path.EndsWith(".markdown")){await next(context);return;}var fileInfo=_fileProvider.GetFileInfo(path);if (!fileInfo.Exists){context.Response.StatusCode = 404;await context.Response.WriteAsync($"Markdown file ({path}) not found");return;}// 读取 Markdown 内容using var stream = fileInfo.CreateReadStream();using var reader = new StreamReader(stream);var markdown = await reader.ReadToEndAsync();// 转换为 HTMLvar html = Markdig.Markdown.ToHtml(markdown);// 嵌入模板var fullHtml = string.Format(_template, html);// 返回响应context.Response.ContentType = "text/html";await context.Response.WriteAsync(fullHtml);}}
}

3）中间件扩展方法

MarkdownRenderingMiddlewareExtensions.cs

using MarkDownMiddleware.Middleware;
using Microsoft.Extensions.FileProviders;namespace MarkDownMiddleware.Extensions
{public static class MarkdownRenderingMiddlewareExtensions{public static IApplicationBuilder UseMarkdownRendering(this IApplicationBuilder app,string templatePath = null,string fileProviderRoot="wwwroot"){var fileProvider=new PhysicalFileProvider(Path.Combine(Directory.GetCurrentDirectory(),fileProviderRoot));string template = null;if (!string.IsNullOrEmpty(templatePath)){var templateFile=fileProvider.GetFileInfo(templatePath);if (templateFile.Exists){using var stream=templateFile.CreateReadStream();using var reader=new StreamReader(stream);template = reader.ReadToEnd();}}return app.UseMiddleware<MarkdownRenderingMiddleware>(fileProvider,template);}}
}

4）在Program.cs配置

Program.cs

using MarkDownMiddleware.Extensions;
using MarkDownMiddleware.Middleware;
using Microsoft.AspNetCore.Mvc.ApplicationParts;
using Microsoft.Extensions.FileProviders;var builder = WebApplication.CreateBuilder(args);// Add services to the container.
builder.Services.AddControllersWithViews();
// 注册 IFileProvider 服务（指向 wwwroot 目录）
builder.Services.AddSingleton<IFileProvider>(new PhysicalFileProvider(builder.Environment.WebRootPath)
);
var app = builder.Build();if (!app.Environment.IsDevelopment())
{app.UseExceptionHandler("/Home/Error");// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.app.UseHsts();
}app.UseHttpsRedirection();
//app.UseMiddleware<MarkdownRenderingMiddleware>();
app.UseMarkdownRendering(templatePath: "/template/layout.html",fileProviderRoot:"Content");
app.UseStaticFiles();app.UseRouting();app.UseAuthorization();app.MapControllerRoute(name: "default",pattern: "{controller=Home}/{action=Index}/{id?}");app.Run();

5）模板文件示例

layout.html

<!-- Content/template/layout.html -->
<!DOCTYPE html>
<html>
<head><meta charset="utf-8"><title>Markdown Render</title><link rel="stylesheet" href="/styles/markdown.css">
</head>
<body><div class="markdown-body">{0} <!-- Markdown 内容插入位置 --></div>
</body>
</html>

6）*.md文件示例

test.md

7）缓存优化

在中间件添加内存缓存

using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.Caching.Memory;namespace MarkDownMiddleware.Middleware
{public class MarkdownRenderingMiddleware{private readonly RequestDelegate next;private readonly IFileProvider _fileProvider;private readonly string _template;private readonly IMemoryCache _memoryCache;public MarkdownRenderingMiddleware(RequestDelegate next,IFileProvider fileProvider,string template = null,IMemoryCache memoryCache = null){this.next = next;_fileProvider = fileProvider;_template = template ?? "<html><body>{0}</body></html>";_memoryCache = memoryCache;}public async Task InvokeAsync(HttpContext context){var path=context.Request.Path.Value;if (!path.EndsWith(".md")&&!path.EndsWith(".markdown")){await next(context);return;}var cacheKey = $"markdown_{path}";if (_memoryCache.TryGetValue(cacheKey, out string cachedHtml)){await context.Response.WriteAsync(cachedHtml);return;}var fileInfo=_fileProvider.GetFileInfo(path);if (!fileInfo.Exists){context.Response.StatusCode = 404;await context.Response.WriteAsync($"Markdown file ({path}) not found");return;}// 读取 Markdown 内容using var stream = fileInfo.CreateReadStream();using var reader = new StreamReader(stream);var markdown = await reader.ReadToEndAsync();// 转换为 HTMLvar html = Markdig.Markdown.ToHtml(markdown);// 嵌入模板var fullHtml = string.Format(_template, html);// 返回响应context.Response.ContentType = "text/html";await context.Response.WriteAsync(fullHtml);_memoryCache.Set(cacheKey, fullHtml, TimeSpan.FromMinutes(10));}}
}