NET怎么实现文件的上传和下载功能_文件上传下载实现教程

[HttpPost("upload")]

public async Task<IActionResult> Upload(IFormFile file)

{

    if (file == null || file.Length == 0)

        return BadRequest("文件为空");

    var uploadDir = Path.Combine(Directory.GetCurrentDirectory(), "uploads");

    Directory.CreateDirectory(uploadDir); // 确保目录存在

    var filePath = Path.Combine(uploadDir, file.FileName);

    await using (var stream = new FileStream(filePath, FileMode.Create))

    {

        await file.CopyToAsync(stream);

    }

    return Ok(new { message = "上传成功", fileName = file.FileName });

}

[HttpGet("download/{fileName}")]

public IActionResult Download(string fileName)

{

    var filePath = Path.Combine(Directory.GetCurrentDirectory(), "uploads", fileName);

    if (!System.IO.File.Exists(filePath))

        return NotFound("文件未找到");

    var fileBytes = System.IO.File.ReadAllBytes(filePath);

    return File(fileBytes, "application/octet-stream", fileName);

}

var fileExtension = Path.GetExtension(file.FileName);

var newFileName = Guid.NewGuid() + fileExtension;

var filePath = Path.Combine(uploadDir, newFileName);

<form action="/api/file/upload" method="post" enctype="multipart/form-data">

  <input type="file" name="file" required />

  <button type="submit">上传文件</button>

</form>

<a href="/api/file/download/test.pdf">下载示例文件</a>