Question

我正在为Windows Phone 8编写一个应用程序。我在FileManager类中有两个方法。一个读，另一个写。

（Over）在Page1.xaml
导航至Page2.xaml
阅读Page2.xaml中的文件
点击物理后退按钮转到Page1.xaml
编辑Page1.xaml中的文件
（Over）在Page1.xaml
导航至Page2.xaml
阅读Page2.xaml中的文件

我可以毫无问题地执行步骤1-5，但是当我到达第6步时应用程序挂起 - 我收到以下错误：

访问被拒绝。（HRESULT异常：0x80070005（E_ACCESSDENIED））

编辑 - 这是代码：

我正在使用来自http://blogs.msdn.com/b/pfxteam/archive/2012/02/12/10266988.aspx

在Page1.xaml.cs中：

    private void appBarButtonSave_Click(object sender, EventArgs e)
    {
        save().Wait();
        NavigationService.Navigate(new Uri("/Page2.xaml", UriKind.Relative));
    }

    private Task save()
    {
        FileManager fileManager = new FileManager();
        return fileManager.WriteToFile("TestFolder", "TestFile.html", "contents as a string");
    }

在Page2.xaml.cs

    public Preview()
    {
        InitializeComponent();

        // Load the Preview
        loadContents();

        // Sample code to localize the ApplicationBar
        BuildLocalizedApplicationBar();

    }

    private async void loadContents()
    {
        FileManager fileManager = new FileManager();
        String strOutput = await fileManager.ReadFromFile("TestFolder", "TestFile.html");
        previewBrowser.NavigateToString(strOutput);
    }

FileManager.cs如下所示：

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using System.Text;
using System.Threading.Tasks;
using Windows.Storage;

namespace MyApp
{
    class FileManager
    {
        StorageFolder local;
        private static readonly AsyncLock m_lock = new AsyncLock();

        public FileManager()
        {
            // Get the local folder
            local = Windows.Storage.ApplicationData.Current.LocalFolder;
        }

        public async Task WriteToFile(String FolderName, String FileName, String contents)
        {
            using (await m_lock.LockAsync())
            {
                // Get the byte array data in String contents 
                byte[] fileBytes = System.Text.Encoding.UTF8.GetBytes(contents.ToCharArray());

                // Create a new folder name, or open it, if it already exists
                var dataFolder = await local.CreateFolderAsync(FolderName.ToString(),
                    CreationCollisionOption.OpenIfExists);

                // Create a new file, or overwrite it's contents if it already exists
                var file = await dataFolder.CreateFileAsync(FileName.ToString(),
                    CreationCollisionOption.ReplaceExisting);

                // Write the data in contents
                using (var s = await file.OpenStreamForWriteAsync())
                {
                    s.Write(fileBytes, 0, fileBytes.Length);
                }
            }
        }

        public async Task<String> ReadFromFile(String FolderName, String FileName)
        {
            using (await m_lock.LockAsync())
            {
                if (local != null)
                {
                    // Get the DataFolder folder
                    var dataFolder = await local.GetFolderAsync(FolderName.ToString());

                    // Get the file
                    var file = await dataFolder.OpenStreamForReadAsync(FileName.ToString());

                    // Read the data
                    using (StreamReader streamReader = new StreamReader(file))
                    {
                        return streamReader.ReadToEnd();
                    }
                }
                else
                {
                    return null;
                }
            }
        }a
    }
}

Answer 1

您在某处遗漏了using（或正确关闭文件）。

写入文件然后读取文件工作正常一次，然后用HRESULT挂起：0x80070005（E_ACCESSDENIED）

1 个答案: