1. 在Blazor页面中，通过使用NavigationManager的NavigateTo方法将文件下载请求发送到控制器：

@inject NavigationManager NavigationManager

Download File

@code {
    private async Task DownloadFile()
    {
        string url = $"{NavigationManager.BaseUri}api/DownloadFile?a=1&b=2&c=3";
        await NavigationManager.NavigateTo(url, forceLoad: true);
    }
}

2. 在WEB API控制器中，通过使用[FromQuery]标记来接收多个参数：

[ApiController]
[Route("api/[controller]")]
public class DownloadFileController : ControllerBase
{
    [HttpGet]
    public IActionResult GetFile([FromQuery] int a, [FromQuery] int b, [FromQuery] int c)
    {
        // Use the parameters a, b, and c to generate or fetch the file
        byte[] fileBytes = GenerateFile(a, b, c);

        // Return the file as a download
        return File(fileBytes, "application/octet-stream", "MyFile.txt");
    }

    private byte[] GenerateFile(int a, int b, int c)
    {
        // Generate or fetch the file, using the arguments a, b, and c
        return Encoding.ASCII.GetBytes($"File with parameters a={a}, b={b}, c={c}");
    }
}