FIleSavePicker保存0个Bytye文件Windows Phone 8 [英] FIleSavePicker saving 0 bytye file Windows Phone 8

问题描述

因此，我现在告诉我，FileSavePicker仅创建一个空白文件，并且必须编写其他代码才能实际写入该文件.我已经在FileSavePicker之后启动了一个Task WriteToFile，但是不确定如何完成它.使用FileSavePicker，用户可以选择要将文件保存到的文件夹.我在哪里指向WriteToFile代码中的内容，以及如何准确地将文件源放入其中?要保存的文件都与应用程序打包在一起.我在这里以x.mp3为例.

So Im now told that the FileSavePicker only creates a blank file, and that Ill have to write additional code to then actually write to the file. Ive started a Task WriteToFile after the FileSavePicker but Im unsure how to finish it. With the FileSavePicker, the user selects the folder they wish to save the file to. Where do I point to that in the WriteToFile code and how exactly do I put the file source in it? The files to be saved are all packaged with the app. Im using x.mp3 as an example here.

    public class SoundData : ViewModelBase
    {
        public string Title { get; set; }
        public string FilePath { get; set; }



        public RelayCommand<string> SaveSoundAs { get; set; }

        private async void ExecuteSaveSoundAs(string soundPath)
        {

        string path = @"appdata:/x.mp3";
        StorageFolder folder = Windows.ApplicationModel.Package.Current.InstalledLocation;
        StorageFile file = await folder.GetFileAsync(path);



                {
                    FileSavePicker savePicker = new FileSavePicker();
                    savePicker.SuggestedSaveFile = file;
                    savePicker.FileTypeChoices.Add("MP3", new List<string>() { ".mp3" });
                    savePicker.ContinuationData.Add("SourceSound", soundPath);
                    savePicker.SuggestedFileName = this.Title;
                    savePicker.PickSaveFileAndContinue();

                }

        }

        public async void ContinueFileSavePicker(FileSavePickerContinuationEventArgs args)
        {
            string soundPath = (string)args.ContinuationData["SourceSound"];
            StorageFile file = args.File;
            if (file != null)
            {
                // Prevent updates to the remote version of the file until we finish making changes and call CompleteUpdatesAsync.
                CachedFileManager.DeferUpdates(file);
                // write to file



                await FileIO.WriteTextAsync(file, file.Name);
                // Let Windows know that we're finished changing the file so the other app can update the remote version of the file.
                // Completing updates may require Windows to ask for user input.
                FileUpdateStatus status = await CachedFileManager.CompleteUpdatesAsync(file);
                if (status == FileUpdateStatus.Complete) ;

            }
        }



        public SoundData()
        {
            SaveSoundAs = new RelayCommand<string>(ExecuteSaveSoundAs);
        }







    }
}

推荐答案

对于Windows Phone，您应遵循以下

For Windows Phone you should follow this How to documentation. The workflow has changed quite a bit from Silverlight apps. Your app no longer resumes like it used to with the old Tasks.

您不需要遵循文档中的所有步骤，但是重要的一点是要遍历App.xaml.cs中的 OnActivated 方法.在其中，您将调用ContinueFileSavePicker方法.

You don't need to follow all of the steps in the doc, but an important piece is to over the OnActivated method within App.xaml.cs. Within there you will call your ContinueFileSavePicker method.

这里是示例，您也可以下载应该会帮助.

Here is a sample that you can download as well that should help.

更新

如果要保存将随应用程序一起提供的文件，请尝试以下代码初始化选择器

If you want to save a file that you will be shipping with your app, try the following code to initialize the picker

// Get the local file that is shipped with the app
// file but be "content" and not "resource"
string path = @"Assets\Audio\Sound.mp3";
StorageFolder folder = Windows.ApplicationModel.Package.Current.InstalledLocation;
StorageFile file = await folder.GetFileAsync(path);

// Show the picker
FileSavePicker savePicker = new FileSavePicker();
// Set the file that will be saved
savePicker.SuggestedSaveFile = file;
savePicker.SuggestedFileName = "Sound";
savePicker.FileTypeChoices.Add("MP3", new List<string>() { ".mp3" });
savePicker.PickSaveFileAndContinue();

您还需要确保侦听PhoneApplicationService的ContractActivated事件.当应用程序从选择器返回时，会触发此事件(在8.1 Silverlight应用程序中).在这里您要调用ContinueFileSavePicker方法.如果您愿意，可以始终将逻辑放在其中.

You also need to make sure that you listen to the ContractActivated event of the PhoneApplicationService. This event is fired (in 8.1 Silverlight apps) when the app returns from the picker. This is where you want to call your ContinueFileSavePicker method. If you wanted, you could always just put the logic in there.

用xaml订阅事件:

<Application.ApplicationLifetimeObjects>
    <!--Required object that handles lifetime events for the application-->
    <shell:PhoneApplicationService
        ContractActivated="Application_ContractActivated"
        Launching="Application_Launching" Closing="Application_Closing"
        Activated="Application_Activated" Deactivated="Application_Deactivated"/>
</Application.ApplicationLifetimeObjects>

在App.xaml.cs中:

And in the App.xaml.cs:

private async void Application_ContractActivated(object sender, Windows.ApplicationModel.Activation.IActivatedEventArgs e)
{
    var args = e as FileSavePickerContinuationEventArgs ;
    if (args != null)
    {
        StorageFile file = args.File; 
        if (file != null) 
        { 
            // Prevent updates to the remote version of the file until we finish making changes and call CompleteUpdatesAsync. 
            CachedFileManager.DeferUpdates(file); 
            // write to file 
            await FileIO.WriteTextAsync(file, file.Name); 
            // Let Windows know that we're finished changing the file so the other app can update the remote version of the file. 
            // Completing updates may require Windows to ask for user input. 
            FileUpdateStatus status = await CachedFileManager.CompleteUpdatesAsync(file); 
        }
    }
}

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