.NET 8 中 使用 IFormFile 上传大文件报错解决方案

前言： 项目中使用 IFormFile写了一个上传文件的api，测试小文件时正常，当上传大文件（几十兆）时如下报错： 使用默认的http启动，如下提示

使用IIS启动，如下报错 Error: Request Entity Too Large 原因： .NET官方出于安全考虑，对body的大小做了限制，超出了限制就会form转化失败，导致我们Reuest.Form为空，最终抛出异常，解决办法也很简单，根据你的启动方式，主要分为三个方面

1. IIS content length limit The default request limit (maxAllowedContentLength) is 30,000,000 bytes, which is approximately 28.6MB. Customize the limit in the web.config file:

    <system.webServer>
      <security>
        <requestFiltering>
          <!-- Handle requests up to 1 GB -->
          <requestLimits maxAllowedContentLength="1073741824" />
        </requestFiltering>
      </security>
    </system.webServer>

Note: Without this application running on IIS would not work.

2. ASP.NET Core Request length limit: For application running on IIS:

     builder.Services.Configure<IISServerOptions>(options =>
     {
          options.MaxRequestBodySize = int.MaxValue;
     });

For application running on Kestrel:

    builder.Services.Configure<KestrelServerOptions>(options =>
    {
         options.Limits.MaxRequestBodySize = int.MaxValue; // if don't set default value is: 30 MB
    });

3. Form's MultipartBodyLengthLimit

    builder.Services.Configure<FormOptions>(x =>
    {
         x.ValueLengthLimit = int.MaxValue;
         x.MultipartBodyLengthLimit = int.MaxValue; // if don't set default value is: 128 MB
         x.MultipartHeadersLengthLimit = int.MaxValue;
    });