转换为Base64时缩小图像大小

时间:2017-01-12 10:16:43

标签: javascript c# cordova asp.net-web-api cordova-plugins

我在JavaScript中使用文件阅读器,我需要将我的图像发布到WebApi并将其转换为字节数组并将其保存在服务器中,其工作正常,现在我的问题是base64字符串增加图像的大小,让我们说如果我上传30Kb的图像,它在服务器中存储有389Kb,如何保存相同尺寸或​​缩小图像尺寸需要帮助

  //File Reader
function OnFileEditImageEntry(file) {
var reader = new FileReader();
reader.onloadend = function (evt) {
    var ImageBase64 = evt.target.result;
    return ImageBase64 ;
};
reader.readAsDataURL(file);
 }

 //WEB API//
public  IHttpActionResult UpdateUserDetails(ImageModel model)
 {

  try
    {
       if (model.ImageBase64 != "")
        {
          var PicDataUrl = "";
           string ftpurl = "ftp://xxx.xxxxx.xxxx/";
           var username = "xxx";
           var password = "xxxxx";
            string UploadDirectory = "xxxx/xx";
             string FileName =model.ImageFileName;
             String uploadUrl = String.Format("{0}{1}/{2}", ftpurl, UploadDirectory,FileName);
                FtpWebRequest req = (FtpWebRequest)FtpWebRequest.Create(uploadUrl);
                req.Proxy = null;
                req.Method = WebRequestMethods.Ftp.UploadFile;
                req.Credentials = new NetworkCredential(username, password);
                req.EnableSsl = false;
                req.UseBinary = true;
                req.UsePassive = true;
                byte[] data =Convert.FromBase64String(model.ImageBase64);
                req.ContentLength = data.Length;
                Stream stream = req.GetRequestStream();
                stream.Write(data, 0, data.Length);
                stream.Close();
     }
      }
    }

1 个答案:

答案 0 :(得分:0)

使用base64 / FileReader

发送原始二进制文件而不是增加大小~30%

with fetch

// sends the raw binary
fetch('http://example.com/upload', {method: 'post', body: file})

// Append the blob/file to a FormData and send it
var fd = new FormData()
fd.append('file', file, file.name)

fetch('http://example.com/upload', {method: 'post', body: fd})

使用XHR

// xhr = new ...
// xhr.open(...)

xhr.send(file) // or
xhr.send(fd) // send the FormData

通常在上传文件时,尽量避免发送json,因为许多开发人员往往会出错。 json中的二进制数据等于不良实践(和更大的大小),例如:

$.post(url, {
  name: '',
  data: base64
})

尽可能使用FormData#append,或者如果您愿意:

fd.append('json', json)