C# Web API 實現上傳功能

  WebApi實現單個文件的上傳下載

上傳和下載是很常用的功能了，只有當用到的時候才發現不會寫...，經過一番百度、篩選、整理修改后，實現了功能，下面簡單的記錄下實現方法。

一、上傳功能

1.前端代碼

上傳文件 <input type="file" id="file" />
<input type="button" id="upload" value="上傳文件" />

<script>
    //上傳
    $("#upload").click(function () {
        var formData = new FormData();
        var file = document.getElementById("file").files[0];
        formData.append("fileInfo", file);
        $.ajax({
            url: "../api/File/UploadFile",
            type: "POST",
            data: formData,
            contentType: false,//必須false才會自動加上正確的Content-Type
            processData: false,//必須false才會避開jQuery對 formdata 的默認處理，XMLHttpRequest會對 formdata 進行正確的處理
            success: function (data) {
                alert(data);
            },
            error: function (data) {
                alert("上傳失敗！");
            }
        });
    });
</script>

2.后台代碼

/// <summary>
        /// 上傳文件
        /// </summary>
        [HttpPost]
        public string UploadFile()
        {
            string result = string.Empty;
            try
            {
                string uploadPath = HttpContext.Current.Server.MapPath("~/App_Data/");
                HttpRequest request = System.Web.HttpContext.Current.Request;
                HttpFileCollection fileCollection = request.Files;
                // 判斷是否有文件
                if (fileCollection.Count > 0)
                {
                    // 獲取文件
                    HttpPostedFile httpPostedFile = fileCollection[0];
                    string fileExtension = Path.GetExtension(httpPostedFile.FileName);// 文件擴展名
                    string fileName = Guid.NewGuid().ToString() + fileExtension;// 名稱
                    string filePath = uploadPath + httpPostedFile.FileName;// 上傳路徑
                    // 如果目錄不存在則要先創建
                    if (!Directory.Exists(uploadPath))
                    {
                        Directory.CreateDirectory(uploadPath);
                    }
                    // 保存新的文件
                    while (File.Exists(filePath))
                    {
                        fileName = Guid.NewGuid().ToString() + fileExtension;
                        filePath = uploadPath + fileName;
                    }
                    httpPostedFile.SaveAs(filePath);
                    result = "上傳成功";
                }
            }
            catch (Exception)
            {
                result = "上傳失敗";
            }
            return result;
        }

 

二、下載功能

1.前端代碼

<form action="../api/File/DownloadFile" method="get" id="form">
   下載文件 <input type="text" id="name" name="fileName" value="222" />
</form>
<input type="button" id="download" value="下載文件" />

<script>
    //下載
    $("#download").click(function () {
        var form = $("#form");
        form.submit();
    });
</script>

2.后台代碼

/// <summary>
        /// 下載文件
        /// </summary>
        [HttpGet]
        public void DownloadFile()
        {
            var request = HttpContext.Current.Request;
            NameValueCollection nvCollection = request.Params;
            string fileName = nvCollection.GetValues("fileName")[0];
            string filePath = Path.Combine(HttpContext.Current.Server.MapPath("~/App_Data/"), fileName);
            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}", fileName));
                response.Charset = "GB2312";
                response.ContentEncoding = Encoding.GetEncoding("GB2312");
                response.ContentType = MimeMapping.GetMimeMapping(fileName);
                response.WriteFile(filePath);
                response.Flush();
                response.Close();
            }
        }