ASP.NET Core应用：文件扫描上传

微软的东西愈来愈棒了，各类开源和跨平台工具相继推出。.NET Core终于让.NET开始像Java同样，能够在任意平台上运行代码。最近学习了下微软的教程，结合跨平台的Dynamic Web TWAIN，分享下个人第一个ASP.NET Core "Hello World"。

安装

• ASP.NET Core
• Dynamic Web TWAIN

Hello World

如何初始化一个ASP.NET Core的工程？根据微软的教程：

mkdir aspnetcoreapp
cd aspnetcoreapp
dotnet new -t web

建立的工程包含了不少的文件，已经比较复杂了。要搞明白发生了什么，仍是一步一步建立文件比较好。因此只须要用命令：

dotnet new

这样会建立一个命令行工程，包含两个文件Program.cs和project.json。我须要的是web server，因此修改下这两个文件。

Program.cs:

using System.IO;
using aspnetcoreapp;
using Microsoft.AspNetCore.Hosting;
 
namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var host = new WebHostBuilder()
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseStartup<Startup>()
                .Build();
 
            host.Run();
        }
    }
}

project.json:

{
  "version": "1.0.0-*",
  "buildOptions": {
    "debugType": "portable",
    "emitEntryPoint": true
  },
  "dependencies": {},
  "frameworks": {
    "netcoreapp1.0": {
      "dependencies": {
        "Microsoft.NETCore.App": {
          "type": "platform",
          "version": "1.0.1"
        },
        "Microsoft.AspNetCore.Server.Kestrel": "1.0.1",
        "Microsoft.AspNetCore.StaticFiles": "1.0.0"
      },
      "imports": "dnxcore50"
    }
  }
}

这里作的事情就是添加了web server Kestrel,以及经过当前路径加载静态文静。还须要建立一个Startup.cs：

using System.IO;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
 
namespace aspnetcoreapp
{
    public class Startup
    {
        public void Configure(IApplicationBuilder app)
        {
            // app.UseDefaultFiles();
            // app.UseStaticFiles();
            app.UseFileServer();
        }
    }
}

UseFileServer等同与UseDefaultFiles+UseStaticFiles。默认加载wwwroot目录下的静态文件，并把index.html看成首页。固然你能够经过代码去修改路径。若是如今部署静态html文件，已经能够访问了。

为了让server端作一点事情，作一个文件上传功能。首先须要映射一下路径，好比上传的url是www.xxx.com/upload。打开index.html作一下修改：

var strActionPage = CurrentPath + "upload";

一旦知足条件就能够执行操做：

using System.IO;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
 
namespace aspnetcoreapp
{
    public class Startup
    {
        public void Configure(IApplicationBuilder app)
        {
            // app.UseDefaultFiles();
            // app.UseStaticFiles();
            app.UseFileServer();
 
            app.Map("/upload", UploadFile);
        }
 
        private static void UploadFile(IApplicationBuilder app)
        {
            app.Run(async context =>
            {
                var files = context.Request.Form.Files;
                var uploads = Path.Combine(Directory.GetCurrentDirectory(), "uploads");
                if (!Directory.Exists(uploads)) {
                    Directory.CreateDirectory(uploads);
                }
 
                foreach (var file in files)
                {
                    var filename = file.FileName;
                    using (var fileStream = new FileStream(Path.Combine(uploads, filename), FileMode.Create))
                    {
                        await file.CopyToAsync(fileStream);
                    }
                }
            });
        }
    }
}

如今能够运行下程序：

dotnet restore
dotnet run

浏览器中打开localhost:5000看到的效果：

MVC

如今用MVC来改造下上面的代码。首先在project.json中添加新的依赖：

{
  "version": "1.0.0-*",
  "buildOptions": {
    "debugType": "portable",
    "emitEntryPoint": true
  },
  "dependencies": {},
  "frameworks": {
    "netcoreapp1.0": {
      "dependencies": {
        "Microsoft.NETCore.App": {
          "type": "platform",
          "version": "1.0.1"
        },
        "Microsoft.AspNetCore.Mvc": "1.0.1",
        "Microsoft.AspNetCore.Server.Kestrel": "1.0.1",
        "Microsoft.AspNetCore.StaticFiles": "1.0.0"
      },
      "imports": "dnxcore50"
    }
  },
 
  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  }
}

在Startup.cs中添加MVC服务：

using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
 
namespace aspnetcoreapp
{
    public class Startup
    {
        public void Configure(IApplicationBuilder app)
        {
            app.UseStaticFiles();
 
            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
 
        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
        }
    }
}

MVC中使用了路径模版。默认状况下须要一个HomeController.cs:

using Microsoft.AspNetCore.Mvc;
 
namespace aspnetcoreapp.Controllers
{
    public class HomeController : Controller
    {
        public IActionResult Index()
        {
            return View();
        }
    }
}

这个文件放在Controller目录下。对应的还有一个Index.cshtml文件，放在Views/Home目录下。把以前的那个index.html改一下名就能够了。

由于上传的URL是www.xxx.com/upload，相对的也要建立一个Controller/UploadController.cs：

using Microsoft.AspNetCore.Mvc;
using System.IO;
 
namespace aspnetcoreapp.Controllers
{
    public class UploadController : Controller
    {
        [HttpPost]
        public void Index()
        {
            var files = Request.Form.Files;
            var uploads = Path.Combine(Directory.GetCurrentDirectory(), "uploads");
            if (!Directory.Exists(uploads))
            {
                Directory.CreateDirectory(uploads);
            }
 
            foreach (var file in files)
            {
                var filename = file.FileName;
                using (var fileStream = new FileStream(Path.Combine(uploads, filename), FileMode.Create))
                {
                    file.CopyTo(fileStream);
                    fileStream.Flush();
                }
            }
        }
    }
}

这样就完成了。

源码

https://github.com/dynamsoft-dwt/ASP.NET-Core