C#MVC通过AJAX调用API方法进行上传下载

//这是写的一个类,具体是上传图片的上传和下载

public class FileResult
    {
        public int Code { get; set; }
        public string Msg { get; set; }
        public string Url { get; set; }
    }

//首先在api方法内新建一个控制器

//控制器内写关于上传和下载的具体代码

// 允许上传的文件扩展名
        public string[] ExtentsfileName = new string[] { ".doc", ".xls", ".png",".jpg" };

public string UrlPath = "/Upload/";

//下载
        [HttpGet]
        public void DownLoad(string Url)
        {
            string filePath = HttpContext.Current.Server.MapPath(Url);
            FileInfo fi = new FileInfo(filePath);
            if (File.Exists(filePath))
            {
                HttpResponse response = HttpContext.Current.Response;
                response.Clear();
                response.ClearHeaders();
                response.ClearContent();
                response.Buffer = true;
                response.AddHeader("content-disposition", string.Format("attachment; FileName={0}", fi.Name));
                response.Charset = "GB2312";
                response.ContentEncoding = Encoding.GetEncoding("GB2312");
                response.ContentType = MimeMapping.GetMimeMapping(fi.Name);
                response.WriteFile(filePath);
                response.Flush();
                response.Close();
            }
        }

//上传
        [HttpPost]
        public FileResult UpLoad()
        {
            var request = HttpContext.Current.Request;
            if (request.Files.Count > 0)
            {
                var file = request.Files[0];
                var extenfilename = Path.GetExtension(file.FileName);

string path = HttpContext.Current.Server.MapPath(UrlPath);
                if (!Directory.Exists(path))
                {
                    Directory.CreateDirectory(path);
                }

if (ExtentsfileName.Contains(extenfilename.ToLower()))
                {
                    string urlfile = UrlPath + DateTime.Now.ToFileTime() + extenfilename;
                    string filepath = HttpContext.Current.Server.MapPath(urlfile);
                    file.SaveAs(filepath);
                    return new FileResult() { Code = 0, Msg = "上传成功", Url = urlfile };
                }
                else
                {
                    return new FileResult() { Code = -1, Msg = "只允许上传指定格式文件"+string.Join(",",ExtentsfileName), Url = "" };
                }
            }
            else
            {
                return new FileResult() { Code = -1, Msg = "不能上传空文件", Url = "" };
            }
        }
    }

//写完api方法之后写mvc前台

<input type = "file" id="f1" />
<input type = "button" value="aa" onclick="ff()"/>

< script >
    function ff()
{
    var formData = new FormData();
    var file = document.getElementById("f1").files[0];
    formData.append("fileInfo", file);
        $.ajax({
    url: "https://localhost:44370/api/FileOperation/UpLoad",
            type: "POST",
            data: formData,
            contentType: false,//必须false才会自动加上正确的Content-Type
            processData: false,//必须false才会避开jQuery对 formdata 的默认处理，XMLHttpRequest会对 formdata 进行正确的处理
            success: function(data) {
            if (data.Code < 0)
                alert(data.Msg)
                else
                alert(data.Url)
            },
            error: function(data) {
            alert("上传失败！");
        }
    });
}

</script>

<a href = "https://localhost:44370/api/FileOperation/DownLoad?Url=/FileUpload/132211303318715030.xls" > 下载 </ a >

//ps记住要在api先加上跨域文件,不然api的方法会传不到mvc,本人经常忘记加跨域文件

原文地址：https://www.cnblogs.com/apf20010807/p/12082315.html