Question

好的，首先，独角兽的头像是搞笑的。说真的，我认为我的帐户遭到了破坏。愚人节快乐。

现在我通过Silverlight将文件上传到服务器。通知Silverlight文件已上传的最佳方法是什么？甚至可能会抛回其他信息，例如成功/失败等。

我遵循了一个简单的教程here来获取我的文件上传逻辑

Answer 1

首先重新编写UploadFile函数，如下所示： -

    private void UploadFile(string fileName, Stream data, Action<Exception> callback)
    {
        UriBuilder ub = new UriBuilder("http://localhost:3840/receiver.ashx");
        ub.Query = string.Format("filename={0}", fileName);

        WebClient c = new WebClient();
        c.OpenWriteCompleted += (sender, e) =>
        {
            try
            {
              PushData(data, e.Result);
              e.Result.Close();
              data.Close();  // This blocks until the upload completes
              callback(null);
            }
            catch (Exception er)
            {
              callback(er);
            }
        };
        c.OpenWriteAsync(ub.Uri);
    }

现在您可以像这样使用此功能： -

   Stream data = new fi.OpenRead();
   try
   {        
       FileUpload(fi.Name, data, (err) => 
        {
           // Note if you want to fiddle with the UI use dispatcher Invoke here.
           if (err == null)
           {
              // Success
           }
           else
           {
              // Fail do something with the err to disply why
           }
        });

    }
    catch
    {
        data.Dispose();
    }

Answer 2

有一种方法可以使用WebClient中的Silverlight上传文件并获取服务器响应。

内部UploadStringAsync通过其编码将字符串转换为字节：

byte[] bytes = this.Encoding.GetBytes(data);

所以，我编写了简单的base64编码包装器（实际上只在我的场景中使用了实际使用的方法）：

  public class WebClientUploaderBase64Encoding : System.Text.Encoding
  {
    public override int GetMaxCharCount(int byteCount) {throw new NotImplementedException();}

    public override int GetMaxByteCount(int charCount){throw new NotImplementedException();}

    public override int GetCharCount(byte[] bytes, int index, int count){throw new NotImplementedException();}

    public override int GetChars(byte[] bytes, int byteIndex, int byteCount, char[] chars, int charIndex){throw new NotImplementedException();}

    public override int GetByteCount(char[] chars, int index, int count)
    {
      var data = System.Convert.FromBase64CharArray(chars, index, count);
      return data.Length;
    }

    public override int GetBytes(char[] chars, int charIndex, int charCount, byte[] bytes, int byteIndex)
    {
      var data = System.Convert.FromBase64CharArray(chars, charIndex, charCount);

      for (int index = 0; index < data.Length; ++index)
        bytes[byteIndex + index] = data[index];
      return data.Length;
    }

    public override string GetString(byte[] bytes, int start, int length)
    {
      return System.Convert.ToBase64String(bytes, start, length);
    }
  }

现在上传的内容如下：

private async Task UploadFile(byte[] data)
{
  var client = new WebClient() {Encoding = new WebClientUploaderBase64Encoding()};
  string base64EncodedData = client.Encoding.GetString(data, 0, data.Length);
  var base64EncodedResult = await client.UploadStringTaskAsync("http://api/query", base64EncodedData);
  var resultBytes = client.Encoding.GetBytes(base64EncodedResult);
  var json = Encoding.UTF8.GetString(resultBytes);
}

Silverlight文件上载后的服务器响应/回调

2 个答案: