public  bool DownLoadFile(DownLoadFileModel file){try{HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://192.168.1.1:8080/" + file.FileName);　　　　　　  //DownLoadFileModel 为我自己定义的一个实体类,文件名需要带后缀名file.request = request;//实体类中将http的请求信息也带进去了，方便回调中的判断request.BeginGetResponse(new AsyncCallback(ResponseCallbackDownLoad), file);//ResponseCallbackDownLoad请求成功后的回调方法return true;}catch {return false;}}

 private  void ResponseCallbackDownLoad(IAsyncResult ar){//throw new NotImplementedException();try{object req = ar.AsyncState as object;;if (req == null) return;DownLoadFileModel file = ar.AsyncState as DownLoadFileModel;//获取异步下载的请求的相关信息，以便判断HttpWebResponse response = file.request.EndGetResponse(ar) as HttpWebResponse;if (response.StatusCode != HttpStatusCode.OK){response.Close();return;}Stream outStream;Stream inStream = response.GetResponseStream();byte[] b = new byte[1024];FileInfo fi = new FileInfo(Application.persistentDataPath+ "//" + file.SaveName);if (fi.Exists){//TODO如果文件件存在，TODO    }else  //else如果该文件不存在{try{int readCount = inStream.Read(b, 0, b.Length);outStream = fi.Create();long fileLength = response.ContentLength;//获取文件总长度long fileSize = 0;//已下载的文件长度while (readCount > 0){outStream.Write(b, 0, readCount);fileSize += readCount;int progress = (int)(((float)fileSize / (float)fileLength) * 100);//progress 为计算下载的百分比readCount = inStream.Read(b, 0, b.Length);}outStream.Close();inStream.Close();response.Close();}}catch (Exception ex){}}}catch (Exception ex){Debug.Log("文件下载失败" + ex.Message);}}
}