C# 线程读写文件

Question

我正在尝试做这样的事情:

我有 3 个包含字符串的文件

1. 读取 3 个文件并创建包含这 3 个文件内容的第四个文件
2. 读取应该通过并行运行的线程完成
3. 第 4 个线程写入第 4 个文件

我的问题是，你如何正确地阅读？ ，如何确保第四个线程仅在所有文件都变为红色后才运行，如何将字符串内容获取到第四个线程？

读取文件后，第四个文件应包含按词典顺序排列的字符串，删除任何空格、符号和重复单词(无需给出其实现，只需建议在何处编码以及如何正确执行)

我使用了任务，我想知道如何使用线程来完成任务 在此代码中，字符串数组用于演示文件

如何在每个线程的“run”函数中正确读取文件？

using System;
using System.Threading.Tasks;
using System.IO;
using System.Text;

class Program {


  static void Main() {

     StringBuilder stringToRead = new StringBuilder();
     StringReader reader;

    Task [] tasks = new Task[3];
    string [] filz = {"aaa" , "bbb" , "ccc"};
    string [] red = new string[filz.Length];

    foreach(string str in filz){
    stringToRead.AppendLine(str);
    }    


     for (int i = 0; i < tasks.Length ; i++)
      {
          tasks[i] = Task.Run(() =>  Console.WriteLine(i)); // it prints 3 , 3 , 3
      }
       try {
         Task.WaitAll(tasks);
      }
      catch (AggregateException ae) {
         Console.WriteLine("One or more exceptions occurred: ");
         foreach (var ex in ae.Flatten().InnerExceptions)
            Console.WriteLine("   {0}", ex.Message);
      }   

      Console.WriteLine("Status of completed tasks:");
      foreach (var t in tasks)
         Console.WriteLine("   Task #{0}: {1}", t.Id, t.Status);

        //now:  
        //4th thread that will writh the 3 previous files that have been red and writh it to a new file


  }
}

Answer 1

以下是在 .NET 框架应用程序中使用 wait 的解决方案:

这是一个按钮点击事件，注意函数定义中的“async”:

private async void button1_Click(object sender, EventArgs e)
{

    List<Task> tasks = new List<Task>();

        string path = "C:\\Temp\\testfileread\\";
        Task<string> file1Read = ReadTextAsync(Path.Combine(path, "test1.txt"));
        Task<string> file2Read = ReadTextAsync(Path.Combine(path, "test2.txt"));
        Task<string> file3Read = ReadTextAsync(Path.Combine(path, "test3.txt"));


        await Task.WhenAll(file1Read, file2Read, file3Read);

        string text1 = await file1Read;
        string text2 = await file2Read;
        string text3 = await file3Read;


        await WriteTextAsync(Path.Combine(path, "result.txt"), text1 + text2 + text3);

}

以下是读写函数:

   private async Task<string> ReadTextAsync(string filePath)
    {
        using (var reader = File.OpenText(filePath))
        {
            var fileText = await reader.ReadToEndAsync();
            return fileText;
        }
    }

    private async Task WriteTextAsync(string filePath, string value)
    {
        using (StreamWriter writer = File.CreateText(filePath))
        {
            await writer.WriteAsync(value);
        }
    }

---

---

---

代码几乎相同，但这里是在 .NET Core 控制台应用程序中完成的解决方案:

static void Main(string[] args)
{
    try
    {
        var result = combineFiles().Result;
    }
    catch (ArgumentException aex)
    {
        Console.WriteLine($"Caught ArgumentException: {aex.Message}");
    }
}

static async Task<bool> combineFiles()
{

    List<Task> tasks = new List<Task>();

    string path = "C:\\Temp\\testfileread\\";
    Task<string> file1Read = ReadTextAsync(Path.Combine(path, "test1.txt"));
    Task<string> file2Read = ReadTextAsync(Path.Combine(path, "test2.txt"));
    Task<string> file3Read = ReadTextAsync(Path.Combine(path, "test3.txt"));


    await Task.WhenAll(file1Read, file2Read, file3Read);

    string text1 = await file1Read;
    string text2 = await file2Read;
    string text3 = await file3Read;


    await WriteTextAsync(Path.Combine(path, "result.txt"), text1 + text2 + text3);

    Console.WriteLine("Finished combining files");
    Console.ReadLine();
    return true;
}


private static async Task<string> ReadTextAsync(string filePath)
{
    using (var reader = File.OpenText(filePath))
    {
        var fileText = await reader.ReadToEndAsync();
        return fileText;
    }
}

private static async Task WriteTextAsync(string filePath, string value)
{
    using (StreamWriter writer = File.CreateText(filePath))
    {
        await writer.WriteAsync(value);
    }
}

不要忘记所需的使用行:

using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;