使用 Windows IoT 在 Raspberry PI 上保存文件

Question

我对使用 Windows IoT 在 Raspberry PI 上保存文件有疑问。

我想做的事情：我有各种要记录的值（温度）。对我来说最简单的方法是编写一个包含所有值的简单 txt 文件。

首先：是否可以在SD卡上本地创建文件？因为我找到的代码示例仅适用于 "normal" Windows 系统：

        if (!File.Exists(path))
    {
        // Create a file to write to.
        string createText = "Hello and Welcome" + Environment.NewLine;
        File.WriteAllText(path, createText);
    }

或 Windows Phone:

      public void createdirectory()
    {
        IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();
        myIsolatedStorage.CreateDirectory("TextFilesFolder");
        filename = "TextFilesFolder\Samplefile.txt";
        Create_new_file();
    }

    public void Create_new_file()
    {
        IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();

        if (!myIsolatedStorage.FileExists(filename))
        {
            using (StreamWriter writeFile = new StreamWriter(new IsolatedStorageFileStream(filename, FileMode.Create, FileAccess.Write, myIsolatedStorage)))
            {
                string someTextData = "This is a test!";
                writeFile.WriteLine(someTextData);
               // writeFile.Close();
            }
        }

Windows Phone 的代码对我来说更有意义。（另一个根本不起作用）。但即使 phone 代码是正确的，我也不知道如何访问内部存储。我试过 IsolatedStorageExplorerTool，但它无法识别我的设备。可能是因为我的设备没有连接 USB... 而且它不是 phone。我用SSH也找不到目录。

也许有人有想法。预先感谢您的帮助！

Answer 1

没关系，我找到了解决方案。 1. 是 Windows phone 的代码。 2. 您必须使用 Windows IoT Core Watcher。右键单击您的设备并打开网络共享。之后我在以下位置找到了文本文件： \\c$\Users\DefaultAccount\AppData\Local\Packages\\LocalState\TextFilesFolder

Answer 2

与文本存储相比，您可以使用序列化进行有组织的存储。

我正在附加静态 class 文件，其中包含序列化和反序列化回原始对象的方法。

Download Source Code

举个概括的例子。假设，您有 Student 和 Mark class，如下所示：

/// <summary>
/// Provides structure for 'Student' entity
/// </summary>
/// 'DataContract' attribute is necessary to serialize object of following class. By removing 'DataContract' attribute, the following class 'Student' will no longer be serialized
[DataContract]
public class Student
{
    [DataMember]
    public ushort Id { get; set; }

    [DataMember]
    public string UserName { get; set; }

    /// <summary>
    /// Password has been marked as non-serializable by removing 'DataContract'
    /// </summary>
    // [DataMember] // Password will not be serialized. Uncomment this line to serialize password
    public string Password { get; set; }

    [DataMember]
    public string FirstName { get; set; }

    [DataMember]
    public string LastName { get; set; }

    [DataMember]
    public List<Mark> Marks { get; set; }
}

[DataContract]
public class Mark
{
    [DataMember]
    public string Subject { get; set; }

    [DataMember]
    public short Percentage { get; set; }
}

Make sure to attribute '[DataContract]' on calss and '[DataMember]' on data member to serialize them else they will be ignore while serializing object

现在，要序列化和反序列化，您将拥有以下具有保存和加载功能的静态 class：

/// <summary>
/// Provides functions to save and load single object as well as List of 'T' using serialization
/// </summary>
/// <typeparam name="T">Type parameter to be serialize</typeparam>
public static class SerializableStorage<T> where T : new()
{
    public static async void Save(string FileName, T _Data)
    {
        MemoryStream _MemoryStream = new MemoryStream();
        DataContractSerializer Serializer = new DataContractSerializer(typeof(T));
        Serializer.WriteObject(_MemoryStream, _Data);

        Task.WaitAll();

        StorageFile _File = await ApplicationData.Current.LocalFolder.CreateFileAsync(FileName, CreationCollisionOption.ReplaceExisting);

        using (Stream fileStream = await _File.OpenStreamForWriteAsync())
        {
            _MemoryStream.Seek(0, SeekOrigin.Begin);
            await _MemoryStream.CopyToAsync(fileStream);
            await fileStream.FlushAsync();
            fileStream.Dispose();
        }
    }

    public static async Task<T> Load(string FileName)
    {
        StorageFolder _Folder = ApplicationData.Current.LocalFolder;
        StorageFile _File;
        T Result;

        try
        {
            Task.WaitAll();
            _File = await _Folder.GetFileAsync(FileName);

            using (Stream stream = await _File.OpenStreamForReadAsync())
            {
                DataContractSerializer Serializer = new DataContractSerializer(typeof(T));

                Result = (T)Serializer.ReadObject(stream);

            }
            return Result;
        }
        catch (Exception ex)
        {
            return new T();
        }
    }
}

现在，让我们看看如何存储学生的对象并从文件中检索它：

/* Create an object of Student class to store */
Student s1 = new Student();
s1.Id = 1;
s1.UserName = "Student1";
s1.Password = "Student123";
s1.FirstName = "Abc";
s1.LastName = "Xyz";
s1.Marks = new List<Mark>();

/* Create list of Marks */
Mark m1 = new Mark();
m1.Subject = "Computer";
m1.Percentage = 89;

Mark m2 = new Mark();
m2.Subject = "Physics";
m2.Percentage = 92;

/* Add marks into Student object */
s1.Marks.Add(m1);
s1.Marks.Add(m2);

/* Store Student object 's1' into file 'MyFile1.dat' */
SerializableStorage<Student>.Save("MyFile1.dat", s1);

/* Load stored student object from 'MyFile1.dat' */
Student s2 = await SerializableStorage<Student>.Load("MyFile1.dat");

您可以序列化和反序列化任何 class。要存储 'Student' 以外的 class 的对象，假设 'MyClass'，只需将函数的 'T' 参数中的 Student 类型替换为如下所示：

/* Store MyClass object 's1' into file 'MyFile1.dat' */
SerializableStorage<MyClass>.Save("MyFile1.dat", s1);

/* Load stored MyClass object from 'MyFile1.dat' */
MyClass s2 = await SerializableStorage<MyClass>.Load("MyFile1.dat");

NOTE: 'MyFile1.dat' will be stored in 'ApplicationData.Current.LocalFolder'. This code is tested on Windows 10 IoT Core (10.0.10586.0) and can work on any UWP app.

Download Source Code

使用 Windows IoT 在 Raspberry PI 上保存文件

Saving files on Raspberry PI with Windows IoT

c#

raspberry-pi

windowsiot