asp. Net coree file upload and download example

asp.net core image springboot Very similar , We're from a springboot File upload and download examples to asp.net core File upload and download ：

this paper asp.net core Version is ：6.0

1 springboot How to upload and download files in

1.1 Upload

stay controller In the receiving MultipartFile that will do .
Front end needs to use form-data The ginseng , The way is as follows ：

2.2 download

Refer to this article ：
spring controller There are two ways to download files

2 Use asp.net core Upload and download files

Or that sentence , Although the official website has been very detailed , But it still looks very abstract 、 obscure .

Here are a few examples to complete the upload and download of files .

2.1 Upload of files

1、 First create a controller
stay asp.net core Of api In service , We need to inherit from ControllerBase class .

[Route("[controller]/[action]")] It means , For example, we have a way uploadFile(), Then the current parameter url Namely ：ip:port/File/uploadFile

[Route("[controller]/[action]")]
[ApiController]
public class FileController : ControllerBase{
    

}

2、 Then we create a class with parameters
Be careful ： there IFormFile For standard springboot Medium MultipartFile, Can receive files directly .
For specific properties and methods, please refer to Microsoft official website .

public class FileParam
{
    
    // file id
    public long? fileId {
     get; set; }
    
    //  file 
    public IFormFile? file{
     get; set;}
}

3、 Start writing specific front-end controllers
Be careful , We need to add [FromForm], Otherwise, we cannot receive the data from the front end .

When we add [FromForm] after ,asp.net core The received parameters will be automatically encapsulated as FileParam class

[Route("[controller]/[action]")]
[ApiController]
public class FileController : ControllerBase{
    

	[HttpPost]
    public ResultVo<bool> uploadFile([FromForm] FileParam fileParam)
    {
    
        //  Upload files 
        string? fileName = fileParam.file?.FileName;
        //  Get the directory of the program 
        string baseDir = System.AppDomain.CurrentDomain.BaseDirectory + "/upload/";
        string filePath = baseDir + fileName;
        //  If the directory does not exist , Create 
        if (!System.IO.Directory.Exists(baseDir)) System.IO.Directory.CreateDirectory(baseDir);
        //  Create a file stream 
        FileStream stream = System.IO.File.Create(filePath);
        //  Write the uploaded file to the stream 
        fileParam.file?.CopyTo(stream);
        //  Closed flow 
        stream.Close();
        return ResultUtil.success(true);
    }
    
}

4、 How to transfer parameters from the front end
Use form-data The ginseng , The way is as follows
Front end needs to use form-data The ginseng , The way is as follows ：

2.2 Download files

Start writing specific front-end controllers
Be careful , Our return value must be IActionResult Or its Subclass 、 Generic

[Route("[controller]/[action]")]
[ApiController]
public class FileController : ControllerBase{
    

	public IActionResult download()
    {
    
        string url = @"D:\xxx\xxx";
        //  Read file information 
        FileInfo fileMetaInfo = new System.IO.FileInfo(url!);
        //  Server file path 
        string strFilePath = url!;
        //  Create file read stream 
        FileStream fileStream = System.IO.File.OpenRead(strFilePath);
        //  Get the... Of the file according to the file suffix ContentType
        var fileExtensionContentTypeProvider = new FileExtensionContentTypeProvider();
        //  Return file contentType type 
        var contentType = fileExtensionContentTypeProvider.Mappings[".png"];
        return File(fileStream, contentType, fileMetaInfo.Name);
    }
    
}