.NET Core Web API 中的图像上传

Question

我正在使用 .Net Core 开发 Web API，我需要允许客户端上传文件列表（主要是图像）并将它们保存到服务器。

我使用 ASP.NET Core 3.0

这是我的启动文件 Startup.cs：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.AspNetCore.Http;


namespace ImageUplaodDemo
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                // 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.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

这是我的 ImageController 文件 ImageController.cs：

using System;
using System.IO;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
namespace ImageUploadDemo.Controllers
{
    [Route("api/[controller]")]
    public class ImageController : ControllerBase
    {
        public static IHostingEnvironment _environment;
        public ImageController(IHostingEnvironment environment)
        {
            _environment = environment;
        }
        public class FIleUploadAPI
        {
            public IFormFile files { get; set; }
        }
        [HttpPost]
        public async Task<string> Post(FIleUploadAPI files)
        {
            if (files.files.Length > 0)
            {
                try
                {
                    if (!Directory.Exists(_environment.WebRootPath + "\\uploads\\"))
                    {
                        Directory.CreateDirectory(_environment.WebRootPath + "\\uploads\\");
                    }
                    using (FileStream filestream = System.IO.File.Create(_environment.WebRootPath + "\\uploads\\" + files.files.FileName))
                    {
                        files.files.CopyTo(filestream);
                        filestream.Flush();
                        return "\\uploads\\" + files.files.FileName;
                    }
                }
                catch (Exception ex)
                {
                    return ex.ToString();
                }
            }
            else
            {
                return "Unsuccessful";
            }
        }
    }
}

我试图通过 POST 操作使用 POSTMAN 上传图像。我将 REQUEST 分配给 POST 并使用 Body 标签下的表单数据，并将 KEY 分配为文件以从桌面上传文件。但我收到以下错误。

我已经尝试了所有可能的方法，但还是遇到了同样的错误...

检查一次代码，需要对代码进行任何修改或对邮递员进行任何修改....

{
    "type": "https://tools.ietf.org/html/rfc7231#section-6.5.13",
    "title": "Unsupported Media Type",
    "status": 415,
    "detail": null,
    "instance": null,
    "extensions": {
        "traceId": "|2c45b532-43521b159e7b734f."
    }
}

Answer 1

[HttpPost("UploadFile")]
 public async Task<string> UploadFile([FromForm] IFormFile file)
    {
        string fName = file.FileName;
        string path = Path.Combine(hostingEnvironment.ContentRootPath, "Images/" + file.FileName);
        using (var stream = new FileStream(path, FileMode.Create))
        {
            await file.CopyToAsync(stream);
        }
        return file.FileName; 
    }

您可以在控制器类中使用它。不需要创建 FileUploadAPi 类。

Answer 2

嘿，你尝试过官方文档吗？

https://learn.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-2.2

这是一个 https://learn.microsoft.com/en-us/aspnet/core/tutorials/first-web-api?view=aspnetcore-2.2&tabs=visual-studio

我会尝试使用官方资源来学习这样的主题，而不是随机的博客。

你的控制器调试了吗？您的视图模型中的 IFormFile 是否已映射？

应自动找到控制器并响应：

http(s)://localhost:DEVPORT/api/Image

您可以添加一个返回字符串“Hello World”的索引端点，当您尝试连接浏览器时，您应该会看到一个 Json Response 。

不确定你为什么要这样做：

app.Run(async (context) =>
            {
                await context.Response.WriteAsync("Controller didn't find anything!");
            });

您在帖子请求中发送了正确的正文吗？