c# - 为通用应用程序读取/写入异步文件

Question

我正在尝试在 C# 中为通用应用程序读取/写入异步文件。 当我第一次写入和读取文件时，它可以工作......但是当我立即重试时，有两个错误:1. UnauthorizedAccess 2. OPLOCK 处理已关闭

看来方法还没有完成，所以数据还没有释放

(在我的框架中有一个按钮，它将新成员添加到列表中，然后该列表应在 XML 数据中序列化。当我重新导航到该页面时，该 XML 工作表应反序列化回该列表，因为内容应显示)

List<Immobilie> immoListe = new List<Immobilie>();
private const string FileName_ImmoObjects = "ImmoObjects.xml";
StorageFolder sFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
IStorageFile latestImmoListFile;

 public Startmenue()
    {
        this.InitializeComponent();
        immoListe.Add(new Immobilie()); // for testing creating an XML first
        immoListe[0].adresse = "Foo1";  
        immoListe.Add(new Immobilie());
        immoListe[1].adresse = "Foo2";
        WriteImmoListAsync();   
        ReadImmoListAsync();   // These two steps working

        WriteImmoListAsync(); // everything more causes error  
        ReadImmoListAsync();   

    }

public async void WriteImmoListAsync()
    {
        try
        {
            IStorageFolder folder = await sFolder.CreateFolderAsync("Saves", CreationCollisionOption.OpenIfExists);
            latestImmoListFile = await folder.CreateFileAsync(FileName_ImmoObjects, CreationCollisionOption.ReplaceExisting);

            using (IRandomAccessStream stream = await latestImmoListFile.OpenAsync(FileAccessMode.ReadWrite))
            using (Stream outputStream = stream.AsStreamForWrite())
            {
                DataContractSerializer serializer = new DataContractSerializer(typeof(List<Immobilie>));
                serializer.WriteObject(outputStream, immoListe);
            }

        }
        catch (Exception e)
        {
            var d = new MessageDialog(e.ToString());
            await d.ShowAsync();
        }
    }



    public async void ReadImmoListAsync()
    {
        int i = 0;
        try
        {
            IStorageFolder folder = await sFolder.GetFolderAsync("Saves");
            i = 1;
            latestImmoListFile = await folder.GetFileAsync(FileName_ImmoObjects);
            i = 2;
            using (IRandomAccessStream stream = await latestImmoListFile.OpenAsync(FileAccessMode.Read))
            {
                i = 3;
                using (Stream inputStream = stream.AsStreamForRead())
                {
                    i = 4;
                    DataContractSerializer deserializer = new DataContractSerializer(typeof(List<Immobilie>));
                    i = 5;
                    immoListe = (List<Immobilie>)deserializer.ReadObject(inputStream);
                }
            }

        }
        catch (Exception e)
        {
            var d = new MessageDialog("Fehler I = " + i + "\n" + e.ToString());
            await d.ShowAsync();
        }
    }

那么我能做什么，为什么这么难？？(普通 I/O 很容易).-.

Answer 1

正如我在关于异步最佳实践的 MSDN 文章中所述，you should avoid async void :

public async Task WriteImmoListAsync();
public async Task ReadImmoListAsync();

一旦您的方法正确异步任务，那么您就可以等待它们:

await WriteImmoListAsync();   
await ReadImmoListAsync();

await WriteImmoListAsync();
await ReadImmoListAsync();