使用 .NET Core 6.0 Web API 上传单个和多个文件

示例代码： https://download.csdn.net/download/hefeng_aspnet/90138968

介绍

我们将在 IFormFile 接口和 .NET 提供的其他接口的帮助下，逐步讨论单个和多个文件上传。

.NET 提供了一个 IFormFile 接口，代表 HTTP 请求中传输的文件。
此外，它还提供许多属性，如 ContentDisposition、ContentType、FileName、Headers、Name 和 Length。
IFormFile还提供了许多方法，如复制请求流内容，打开请求流进行读取等等。

先决条件

.NET Core 6 SDK
Visual Studio 2022
SQL Server
Postman

逐步实施

步骤 1.创建一个新的 .NET Core Web API。

第 2 步。安装以下 NuGet 包。

步骤3.创建以下文件实体。

FileDetails.cs

using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;

namespace FileUpload.Entities
{
[Table("FileDetails")]
public class FileDetails
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
public string FileName { get; set; }
public byte[] FileData { get; set; }
public FileType FileType { get; set; }
}
}

FileUploadModel.cs

namespace FileUpload.Entities
{
public class FileUploadModel
{
public IFormFile FileDetails { get; set; }
public FileType FileType { get; set; }
}
}

FileType

namespace FileUpload.Entities
{
public enum FileType
{
PDF = 1,
DOCX = 2
}
}

步骤4.接下来，Data文件夹内的DbContextClass.cs类。

using FileUpload.Entities;
using Microsoft.EntityFrameworkCore;

namespace FileUpload.Data
{
public class DbContextClass : DbContext
{
protected readonly IConfiguration Configuration;

public DbContextClass(IConfiguration configuration)
{
Configuration = configuration;
}
protected override void OnConfiguring(DbContextOptionsBuilder options)
{
options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
}

public DbSet<FileDetails> FileDetails { get; set; }
}
}

步骤5.创建IFileService和FileService文件。

IFileService.cs

using FileUpload.Entities;

namespace FileUpload.Services
{
public interface IFileService
{
public Task PostFileAsync(IFormFile fileData, FileType fileType);

public Task PostMultiFileAsync(List<FileUploadModel> fileData);

public Task DownloadFileById(int fileName);
}
}

FileService.cs

using FileUpload.Data;
using FileUpload.Entities;
using Microsoft.EntityFrameworkCore;

namespace FileUpload.Services
{
public class FileService : IFileService
{
private readonly DbContextClass dbContextClass;

public FileService(DbContextClass dbContextClass)
{
this.dbContextClass = dbContextClass;
}

public async Task PostFileAsync(IFormFile fileData, FileType fileType)
{
try
{
var fileDetails = new FileDetails()
{
ID = 0,
FileName = fileData.FileName,
FileType = fileType,
};

using (var stream = new MemoryStream())
{
fileData.CopyTo(stream);
fileDetails.FileData = stream.ToArray();
}

var result = dbContextClass.FileDetails.Add(fileDetails);
await dbContextClass.SaveChangesAsync();
}
catch (Exception)
{
throw;
}
}

public async Task PostMultiFileAsync(List<FileUploadModel> fileData)
{
try
{
foreach(FileUploadModel file in fileData)
{
var fileDetails = new FileDetails()
{
ID = 0,
FileName = file.FileDetails.FileName,
FileType = file.FileType,
};

using (var stream = new MemoryStream())
{
file.FileDetails.CopyTo(stream);
fileDetails.FileData = stream.ToArray();
}

var result = dbContextClass.FileDetails.Add(fileDetails);
}
await dbContextClass.SaveChangesAsync();
}
catch (Exception)
{
throw;
}
}

public async Task DownloadFileById(int Id)
{
try
{
var file = dbContextClass.FileDetails.Where(x => x.ID == Id).FirstOrDefaultAsync();

var content = new System.IO.MemoryStream(file.Result.FileData);
var path = Path.Combine(
Directory.GetCurrentDirectory(), "FileDownloaded",
file.Result.FileName);

await CopyStream(content, path);
}
catch (Exception)
{
throw;
}
}

public async Task CopyStream(Stream stream, string downloadPath)
{
using (var fileStream = new FileStream(downloadPath, FileMode.Create, FileAccess.Write))
{
await stream.CopyToAsync(fileStream);
}
}
}
}

步骤6.在控制器部分内创建FilesController.cs。

FilesController.cs

using FileUpload.Entities;
using FileUpload.Services;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

namespace FileUpload.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class FilesController : ControllerBase
{
private readonly IFileService _uploadService;

public FilesController(IFileService uploadService)
{
_uploadService = uploadService;
}

/// <summary>
/// Single File Upload
/// </summary>
/// <param name="file"></param>
/// <returns></returns>
[HttpPost("PostSingleFile")]
public async Task<ActionResult> PostSingleFile([FromForm] FileUploadModel fileDetails)
{
if(fileDetails == null)
{
return BadRequest();
}

try
{
await _uploadService.PostFileAsync(fileDetails.FileDetails, fileDetails.FileType);
return Ok();
}
catch (Exception)
{
throw;
}
}

/// <summary>
/// Multiple File Upload
/// </summary>
/// <param name="file"></param>
/// <returns></returns>
[HttpPost("PostMultipleFile")]
public async Task<ActionResult> PostMultipleFile([FromForm] List<FileUploadModel> fileDetails)
{
if (fileDetails == null)
{
return BadRequest();
}

try
{
await _uploadService.PostMultiFileAsync(fileDetails);
return Ok();
}
catch (Exception)
{
throw;
}
}

/// <summary>
/// Download File
/// </summary>
/// <param name="file"></param>
/// <returns></returns>
[HttpGet("DownloadFile")]
public async Task<ActionResult> DownloadFile(int id)
{
if (id < 1)
{
return BadRequest();
}

try
{
await _uploadService.DownloadFileById(id);
return Ok();
}
catch (Exception)
{
throw;
}
}
}
}

第七步，在程序类和DI容器内配置一些服务。

using FileUpload.Data;
using FileUpload.Services;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddDbContext < DbContextClass > ();
builder.Services.AddScoped < IFileService, FileService > ();
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment()) {
app.UseSwagger();
app.UseSwaggerUI();
}
app.UseAuthorization();
app.MapControllers();
app.Run();

步骤8.在SQL Server中创建一个新的数据库并将其命名为FileUploadDemo。

步骤9.接下来，使用以下脚本创建FileDetails表。

USE [FileUploadDemo]
GO

/****** Object: Table [dbo].[FileDetails] Script Date: 10/1/2022 5:51:22 PM ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[FileDetails](
   [ID] [int] IDENTITY(1,1) NOT NULL,
   [FileName] [nvarchar](80) NOT NULL,
   [FileData] [varbinary](max) NOT NULL,
   [FileType] [int] NULL,
CONSTRAINT [PK_FileDetails] PRIMARY KEY CLUSTERED
(
   [ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO

第十步. 将数据库连接放入 appsettings.json 文件中。

{
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft.AspNetCore": "Warning"
}
},
"AllowedHosts": "*",
"ConnectionStrings": {
"DefaultConnection": "Data Source=DESKTOP-****;;Initial Catalog=FileUploadDemo;User Id=sa;Password=database;"
}
}

第 11 步. 最后，我们运行该应用程序。