docs/csharp/asynchronous-programming/snippets/file-access/Program.cs - main - aprogrammer/dotnet-docs

docs/csharp/asynchronous-programming/snippets/file-access/Program.cs
179 строк5 KB
Bill Wagner
Create async section (#33921)
13 фев 2023, 19:07
13 фев 2023, 19:0753bc3af
using System.Text;

class Program
{
    static async Task Main()
    {
        await WriteText.Example.ProcessWriteAsync();
        await WriteText.Example.SimpleWriteAsync();

        await ReadText.Example.ProcessReadAsync();
        await ReadText.Example.SimpleReadAsync();

        await ParallelWriteText.Example.ProcessMultipleWritesAsync();
        await ParallelWriteText.Example.SimpleParallelWriteAsync();
    }
}

class WriteText
{
    public static WriteText Example = new WriteText();

    // <SimpleWrite>
    public async Task SimpleWriteAsync()
    {
        string filePath = "simple.txt";
        string text = $"Hello World";

        await File.WriteAllTextAsync(filePath, text);
    }
    // </SimpleWrite>

    // <WriteText>
    public async Task ProcessWriteAsync()
    {
        string filePath = "temp.txt";
        string text = $"Hello World{Environment.NewLine}";

        await WriteTextAsync(filePath, text);
    }

    async Task WriteTextAsync(string filePath, string text)
    {
        byte[] encodedText = Encoding.Unicode.GetBytes(text);

        using var sourceStream =
            new FileStream(
                filePath,
                FileMode.Create, FileAccess.Write, FileShare.None,
                bufferSize: 4096, useAsync: true);

        await sourceStream.WriteAsync(encodedText, 0, encodedText.Length);
    }
    // </WriteText>
}

class ReadText
{
    public static ReadText Example = new ReadText();

    // <SimpleRead>
    public async Task SimpleReadAsync()
    {
        string filePath = "simple.txt";
        string text = await File.ReadAllTextAsync(filePath);

        Console.WriteLine(text);
    }
    // </SimpleRead>

    // <ReadText>
    public async Task ProcessReadAsync()
    {
        try
        {
            string filePath = "temp.txt";
            if (File.Exists(filePath) != false)
            {
                string text = await ReadTextAsync(filePath);
                Console.WriteLine(text);
            }
            else
            {
                Console.WriteLine($"file not found: {filePath}");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }

    async Task<string> ReadTextAsync(string filePath)
    {
        using var sourceStream =
            new FileStream(
                filePath,
                FileMode.Open, FileAccess.Read, FileShare.Read,
                bufferSize: 4096, useAsync: true);

        var sb = new StringBuilder();

        byte[] buffer = new byte[0x1000];
        int numRead;
        while ((numRead = await sourceStream.ReadAsync(buffer, 0, buffer.Length)) != 0)
        {
            string text = Encoding.Unicode.GetString(buffer, 0, numRead);
            sb.Append(text);
        }

        return sb.ToString();
    }
    // </ReadText>
}

class ParallelWriteText
{
    public static ParallelWriteText Example = new ParallelWriteText();

    // <SimpleParallelWrite>
    public async Task SimpleParallelWriteAsync()
    {
        string folder = Directory.CreateDirectory("tempfolder").Name;
        IList<Task> writeTaskList = new List<Task>();

        for (int index = 11; index <= 20; ++ index)
        {
            string fileName = $"file-{index:00}.txt";
            string filePath = $"{folder}/{fileName}";
            string text = $"In file {index}{Environment.NewLine}";

            writeTaskList.Add(File.WriteAllTextAsync(filePath, text));
        }

        await Task.WhenAll(writeTaskList);
    }
    // </SimpleParallelWrite>

    // <ParallelWriteText>
    public async Task ProcessMultipleWritesAsync()
    {
        IList<FileStream> sourceStreams = new List<FileStream>();

        try
        {
            string folder = Directory.CreateDirectory("tempfolder").Name;
            IList<Task> writeTaskList = new List<Task>();

            for (int index = 1; index <= 10; ++ index)
            {
                string fileName = $"file-{index:00}.txt";
                string filePath = $"{folder}/{fileName}";

                string text = $"In file {index}{Environment.NewLine}";
                byte[] encodedText = Encoding.Unicode.GetBytes(text);

                var sourceStream =
                    new FileStream(
                        filePath,
                        FileMode.Create, FileAccess.Write, FileShare.None,
                        bufferSize: 4096, useAsync: true);

                Task writeTask = sourceStream.WriteAsync(encodedText, 0, encodedText.Length);
                sourceStreams.Add(sourceStream);

                writeTaskList.Add(writeTask);
            }

            await Task.WhenAll(writeTaskList);
        }
        finally
        {
            foreach (FileStream sourceStream in sourceStreams)
            {
                sourceStream.Close();
            }
        }
    }
    // </ParallelWriteText>
}