ASP.NET Core实现文件上传和下载代码示例

本篇文章小编给大家分享一下ASP.NET Core实现文件上传和下载代码示例，文章代码介绍的很详细，小编觉得挺不错的，现在分享给大家供大家参考，有需要的小伙伴们可以来看看。

一、文件上传

1.1 获取文件后缀

/// 

/// 获取文件后缀
/// 
/// 文件名称
/// 
        public async static Task GetFileSuffixAsync(string fileName)
        {
            return await Task.Run(() =>
            {
                string suffix = Path.GetExtension(fileName);
                return suffix;
            });
        }

1.2 上传单文件

public class FileMessage
    {
        /// 

        /// 原文件名称
        /// 
        public string FileName { get; set; }

        /// 

        /// 附件名称(协议或其他要进行数据库保存与模型绑定的命名)
        /// 
        public string ArgumentName { get; set; }

        /// 

        /// 文件大小(KB)
        /// 
        public string FileSize { get; set; }

        /// 

        /// -1：上传失败 0：等待上传 1：已上传
        /// 
        public int FileStatus { get; set; }

        /// 

        /// 上传结果
        /// 
        public string UploadResult { get; set; }

        /// 

        /// 创建实例
        /// 
        /// 原文件名称
        /// (新)附件名称
        /// 大小
        /// 文件状态
        /// 
        public static FileMessage CreateNew(string fileName,
            string argumentName,
            string fileSize,
            int fileStatus,
            string uploadResult)
        {
            return new FileMessage()
            {
                FileName = fileName,
                ArgumentName = argumentName,
                FileSize = fileSize,
                FileStatus = fileStatus,
                UploadResult = uploadResult
            };
        }
    }

/// 

/// 上传文件
 /// 
 /// 上传的文件
 /// 要存储的文件夹
 /// 
        public async static Task UploadFileAsync(IFormFile file, string fold)
        {
            string fileName = file.FileName;
            string path = Directory.GetCurrentDirectory() + @"/Upload/" + fold + "/";
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
            string argumentName = DateTime.Now.ToString("yyyyMMddHHmmssfff") + await GetFileSuffixAsync(file.FileName);
            string fileSize = Math.Round((decimal)file.Length / 1024, 2) + "k";
            string filePath = Path.Combine(path, argumentName);
            try
            {
                using (FileStream stream = new FileStream(filePath, FileMode.Create))
                {
                    await file.CopyToAsync(stream);
                }
                return FileMessage.CreateNew(fileName, argumentName, fileSize, 1, "文件上传成功");
            }
            catch (Exception e)
            {
                return FileMessage.CreateNew(fileName, argumentName, fileSize, -1, "文件上传失败：" + e.Message);
            }
        }

1.3 上传多文件

/// 

/// 上传多文件
/// 
/// 上传的文件集合
/// 要存储的文件夹
/// 
        public async static Task> UploadFilesAsync(IFormFileCollection files, string fold)
        {
            string path = Directory.GetCurrentDirectory() + @"/Upload/" + fold + "/";
            if (!Directory.Exists(path))
            {
                Directory.CreateDirectory(path);
            }
            List messages = new List();
            foreach (var file in files)
            {
                string fileName = file.FileName;
                string argumentName = DateTime.Now.ToString("yyyyMMddHHmmssfff") + await GetFileSuffixAsync(file.FileName);
                string fileSize = Math.Round((decimal)file.Length / 1024, 2) + "k";
                string filePath = Path.Combine(path, argumentName);
                try
                {
                    using (FileStream stream = new FileStream(filePath, FileMode.Create))
                    {
                        await file.CopyToAsync(stream);
                    }
                    messages.Add(FileMessage.CreateNew(fileName, argumentName, fileSize, 1, "文件上传成功"));
                }
                catch (Exception e)
                {
                    messages.Add(FileMessage.CreateNew(fileName, argumentName, fileSize, -1, "文件上传失败，失败原因：" + e.Message));
                }
            }
            return messages;
        }

[Route("api/[controller]")]
    [ApiController]
    public class ManageProtocolFileController : ControllerBase
    {
        private readonly string createName = "";
        private readonly IWebHostEnvironment _env;
        private readonly ILogger _logger;
        public ManageProtocolFileController(IWebHostEnvironment env,
            ILogger logger)
        {
            _env = env;
            _logger = logger;
        }
        
        /// 

        /// 协议上传附件
        /// 
        /// 
        /// 
        [HttpPost("upload")]
        public async Task UploadProtocolFile([FromForm] IFormFile file)
        {
            return await UploadFileAsync(file, "ManageProtocol");
        }
    }

二、文件下载

2.1 获取ContentType属性

/// 

/// 获取文件ContentType
/// 
/// 文件名称
 /// 
        public async static Task GetFileContentTypeAsync(string fileName)
        {
            return await Task.Run(() =>
            {
                string suffix = Path.GetExtension(fileName);
                var provider = new FileExtensionContentTypeProvider();
                var contentType = provider.Mappings[suffix];
                return contentType;
            });
        }

2.2 执行下载

[Route("api/[controller]")]
[ApiController]
    public class ManageProtocolFileController : ControllerBase
    {
        private readonly string createName = "";
        private readonly IWebHostEnvironment _env;
        private readonly ILogger _logger;
        public ManageProtocolFileController(IWebHostEnvironment env,
            ILogger logger)
        {
            _env = env;
            _logger = logger;
        }
        
        /// 

        /// 下载附件
        /// 
        /// 文件名称
        /// 
        [HttpGet("download")]
        public async Task Download([FromQuery] string fileName)
        {
            try
            {
                string rootPath = _env.ContentRootPath + @"/Upload/ManageProtocolFile";
                string filePath = Path.Combine(rootPath, fileName);
                var stream = System.IO.File.OpenRead(filePath);
                string contentType = await GetFileContentTypeAsync(fileName);
                _logger.LogInformation("用户:" + createName + "下载后台客户协议附件:" + request.FileName);
                return File(stream, contentType, fileName);
            }
            catch (Exception e)
            {
                _logger.LogError(e, "用户:" + createName + "下载后台客户协议附件出错，出错原因:" + e.Message);
                throw new Exception(e.ToString());
            }
        }
}