Question

我想将zip文件直接保存到服务器的隔离存储中，但我遇到的问题是当我尝试使用下面的代码进行保存时，由于我的文件大小为＆gt;有时150 MB。所以我发布了一个问题here，建议是

你可以将这样的文件直接下载到IsolatedStorage，但是如果你想把它放到内存中 - 可能会有问题。

那么如何将文件从服务器直接保存到隔离存储而不保存到内存。我使用的代码发布在这里

client = new WebClient();
    client.OpenReadCompleted += new OpenReadCompletedEventHandler(client_OpenReadCompleted);
    client.OpenReadAsync(new Uri(fileurl), objRef);

    private async void client_OpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
    {

            var file = IsolatedStorageFile.GetUserStoreForApplication();
            if (!file.DirectoryExists("Folderpath/Files"))
            {
                file.CreateDirectory("Folderpath/Files");
            }
            string hpubFile = "/Folderpath/Files/fileName" ;
            using (IsolatedStorageFileStream stream = new IsolatedStorageFileStream(hpubFile, System.IO.FileMode.OpenOrCreate, FileAccess.ReadWrite, file))
            {
                byte[] buffer = new byte[1024];
                while (e.Result.Read(buffer, 0, buffer.Length) > 0)
                {
                    stream.Write(buffer, 0, buffer.Length);
                }
            }
        }
    }

Answer 1

然后尝试这样的方法 - 用HttpWebRequest做到这一点：

public static class Extensions
{
    public static Task<HttpWebResponse> GetResponseAsync(this HttpWebRequest webRequest)
    {
        TaskCompletionSource<HttpWebResponse> taskComplete = new TaskCompletionSource<HttpWebResponse>();
        webRequest.BeginGetResponse(
            asyncResponse =>
            {
                try
                {
                    HttpWebRequest responseRequest = (HttpWebRequest)asyncResponse.AsyncState;
                    HttpWebResponse someResponse = (HttpWebResponse)responseRequest.EndGetResponse(asyncResponse);
                    taskComplete.TrySetResult(someResponse);
                }
                catch (WebException webExc)
                {
                    HttpWebResponse failedResponse = (HttpWebResponse)webExc.Response;
                    taskComplete.TrySetResult(failedResponse);
                }
                catch (Exception exc) { taskComplete.SetException(exc); }
            }, webRequest);
        return taskComplete.Task;
    }
}

2。然后修改您的代码以使用它：

CancellationTokenSource cts = new CancellationTokenSource();
enum Problem { Ok, Cancelled, Other };

public async Task<Problem> DownloadFileFromWeb(Uri uriToDownload, string fileName, CancellationToken cToken)
{
    try
    {
        HttpWebRequest wbr = WebRequest.CreateHttp(uriToDownload);
        wbr.Method = "GET";
        wbr.AllowReadStreamBuffering = false;
        WebClient wbc = new WebClient();

        using (HttpWebResponse response = await wbr.GetResponseAsync())
        {
            using (Stream mystr = response.GetResponseStream())
            {
                using (IsolatedStorageFile ISF = IsolatedStorageFile.GetUserStoreForApplication())
                  {
                      if (ISF.FileExists(fileName)) return Problem.Other;
                      using (IsolatedStorageFileStream file = ISF.CreateFile(fileName))
                      {
                          const int BUFFER_SIZE = 100 * 1024;
                          byte[] buf = new byte[BUFFER_SIZE];

                          int bytesread = 0;
                          while ((bytesread = await mystr.ReadAsync(buf, 0, BUFFER_SIZE)) > 0)
                          {
                              cToken.ThrowIfCancellationRequested();
                              file.Write(buf, 0, bytesread);
                          }
                      }
                  }
                  return Problem.Ok;
              }
          }
      }
      catch (Exception exc)
      {
          if (exc is OperationCanceledException)
              return Problem.Cancelled;
          else return Problem.Other; 
      }
  }

3。并下载：

  private async void Downlaod_Click(object sender, RoutedEventArgs e)
  {
      cts = new CancellationTokenSource();
      Problem fileDownloaded = await DownloadFileFromWeb(new Uri(@"http://filedress/myfile.txt", UriKind.Absolute), "myfile.txt", cts.Token);
      switch(fileDownloaded)
      {
          case Problem.Ok:
              MessageBox.Show("Problem with download");
              break;
          case Problem.Cancelled:
              MessageBox.Show("Download cancelled");
              break;
          case Problem.Other:
          default:
              MessageBox.Show("Other problem with download");
              break;
      }
  }

因为我有我的WebResponse，我从中获取一个流然后将其读取为异步。
请注意，我没有对上面的代码进行过测试，但希望它可以为您提供一些如何工作的建议。

Answer 2

是的，您可以这样做，就像首先在Sqlite文件中保存原始数据并在代码中使用，然后调用服务器进行数据中的更改并获取这些更新，这样您就不必再次下载数据了然后再次.. 此外，如果您必须在每次调用时下载数据，则可以使用sqlite或linq。

直接在WP8中保存到隔离存储

2 个答案: