FlashToQiNiu.as

//ActionScript3 upload file to qiniu.com

var u:URLRequest=new URLRequest('http://up.qiniu.com'); 
u.method=URLRequestMethod.POST;
u.requestHeaders=[new URLRequestHeader('enctype', 'multipart/form-data')];
var ur:URLVariables=new URLVariables();
ur.key='Your file name in qiniu.com';
ur.token='Your uptoken from server'; //Only this is required
ur['x:param'] = 'Your custom param and value';
u.data=ur;

f.upload(u, 'file');  //File or FileReference is both OK, but UploadDataFieldName must be 'file'
f.addEventListener(DataEvent.UPLOAD_COMPLETE_DATA, uploadedHandler);

protected function uploadedHandler(event:DataEvent):void
{
  trace(event.data);  //{"hash":"File hash info","key":"Uploaded file name", "x:param":"Your custom param and value"}
}