详细总结C#中的文件和I/O流之文件和目录（File 、 FileInfo、Directory、DirectoryInfo和Path）

例如：
//DateTime(int year, int month, int day, int hour, int minute, int second);
var date1 = new DateTime(2008, 3, 1, 7, 0, 0);
Console.WriteLine(date1.ToString("yyyyMMddTHH:mm:ssZ"));

using System;
using System.IO;
using System.Text;
class Test
    public static void Main()
        string path = @"G:\Desktop\MyTest.txt";
        if (!File.Exists(path))
            //写入内容到文件
            using (StreamWriter sw = File.CreateText(path))
                sw.WriteLine("Hello");
                sw.WriteLine("And");
                sw.WriteLine("Welcome");
        //复制文件
        string path1 = @"G:\Desktop\MyTest1.txt";
        File.Copy(path, path1,true);
        // 读取复制的文件中的内容
        using (StreamReader sr = File.OpenText(path1))
            string s;
            while ((s = sr.ReadLine()) != null)
                Console.WriteLine(s);
        //获取上次访问指定文件或目录的日期和时间
        DateTime datetime = File.GetLastAccessTime(path1);
        Console.WriteLine(datetime.ToString());
        //设置创建该文件的日期和时间
        DateTime Createtime = new DateTime(2008,3,1,7,0,0);
        Console.WriteLine(Createtime.ToString("yyyyMMddTHH:mm:ssZ"));
        File.SetCreationTime(path1, Createtime);
        //打开文件并向其中追加指定的字符串
        //var file1 = new File(path1);//它不属于特定对象，所以不能被实例化。
        string alltext = "欢迎关注\n" +
                        "智能建造小硕";
        File.AppendAllText(path1, alltext);
        //读取文件中的字符串并在控制台输出
        string allcontent =  File.ReadAllText(path1, encoding:Encoding.UTF8);
        Console.Write(allcontent);

Hello
Welcome
2022/8/23 14:42:55
20080301T07:00:00Z
Hello
Welcome
智能建造小硕

using System;
using System.Diagnostics;
using System.IO;
using System.Text;
using static System.Net.Mime.MediaTypeNames;
class Test
    public static void Main()
        //磁盘上创建一个唯一命名的零字节临时文件并返回该文件的完整路径。
        string path = Path.GetTempFileName();
        //以Path实例化一个FileInfo
        FileInfo fi1 = new FileInfo(path);
        // 使用CreateText()写入数据
        using (StreamWriter sw = fi1.CreateText())
            sw.WriteLine("Hello");
            sw.WriteLine("And");
            sw.WriteLine("Welcome");
        // 使用OpenText读取数据
        using (StreamReader sr = fi1.OpenText())
            var s = "";
            while ((s = sr.ReadLine()) != null) //一行一行的读，如果是空行不打印
                Console.WriteLine(s);
            String path2 = @"G:\Desktop\Test.txt";
            // 复制文件到path2
            FileInfo file2 = fi1.CopyTo(path2, true);
            Console.WriteLine($"{fi1.FullName} 复制到 {file2.Name}.");
            File.Create(@"G:\Desktop\Test3.txt").Close();
            //查看文件大小            
            string s = file2.Length.ToString();
            Console.WriteLine(s);
            using (StreamReader sr = file2.OpenText())
                String ss;
                while ((ss = sr.ReadLine()) != null)
                    Console.WriteLine(ss);
            // 删除复制的文件
            file2.Delete();
            //判断是否存在文件
            string A;
            if (file2.Exists)
            { A = "存在"; }
            { A = "不存在"; }
            Console.WriteLine($"文件{A}");
        catch (Exception e)
            Console.WriteLine($"运行时出错: {e.ToString()}");

Hello
Welcome
C:\Users\24576\AppData\Local\Temp\tmpBA66.tmp 复制到 Test.txt.
Hello
Welcome
文件不存在

public static void Main()
        //新建两个目录
        string sourceDirectory = @"G:\Desktop\current";
        string archiveDirectory = @"G:\Desktop\archive";
        Directory.CreateDirectory(sourceDirectory);
        Directory.CreateDirectory(archiveDirectory);
        //手动把一些文件放入current文件夹哈
            Console.WriteLine("###移动一个文件夹的文件到另一文件夹###".PadLeft(30));
            //返回指定路径中的目录完整名称的可枚举集合，
            //"*.txt"表示匹配任意文件名加.TXT后缀（也叫做扩展名）的文件
            var txtFiles = Directory.EnumerateFiles(sourceDirectory, "*.txt");
            //txtFiles为一个可迭代的对象
            foreach (string currentFile in txtFiles)
                //Substring截取字符串，返回截取范围外的字符
                string fileName = currentFile.Substring(sourceDirectory.Length + 1);
                //移动文件或文件夹
                Directory.Move(currentFile, Path.Combine(archiveDirectory, fileName));
            var filess = Directory.GetFiles(archiveDirectory);
            Console.WriteLine($"移动完毕,移动了{filess.Length}个文件");
            Console.WriteLine("从目录中检索文本文件的集合，然后在查询中使用该集合查找包含“Example”的所有行".PadLeft(30));
            //C#中的lambda表达式
            //from：用来表示迭代变量；
            //in：表示迭代的集合；
            //select：表示我们需要去让什么变量作为返回；
            //into：表示继续使用迭代结果；
            //where：表示条件；
            var files = 
                    from retrievedFile in Directory.GetFiles(archiveDirectory, "*.txt", SearchOption.AllDirectories)
                    from line in File.ReadLines(retrievedFile) where line.Contains("Example")
                    select new  {
                        File = retrievedFile,
                        Line = line
            foreach (var f in files)
                Console.WriteLine("{0} 包含 {1}", f.File, f.Line);
            Console.WriteLine("找到{0}行", files.Count().ToString());
            //获取当前的程序运行的目录
            Console.WriteLine(Directory.GetCurrentDirectory());           
        catch (Exception e)
            Console.WriteLine(e.Message);

        ###移动一个文件夹的文件到另一文件夹###
移动完毕,移动了3个文件
从目录中检索文本文件的集合，然后在查询中使用该集合查找包含“Example”的所有行
G:\Desktop\archive\MyTest.txt 包含 Welcome Example
G:\Desktop\archive\MyTest.txt 包含 Example
G:\Desktop\archive\Test3.txt 包含 ExampleExample
G:\Desktop\archive\Test3.txt 包含 Example
找到4行
G:\Desktop\博客文章\C#高级基础学习\Practice2\FileAndStream\ConsoleApp1\bin\Debug\net6.0

public static void Main()
        // 实例化需要进行操作的文件
        DirectoryInfo di = new DirectoryInfo(@"G:\Desktop\archive");
        DirectoryInfo di1 = new DirectoryInfo(@"G:\Desktop\archive1");
        // 创建archive1文件夹
        di1.Create();
            // 是否存在
            if (di.Exists)
                Console.WriteLine("文件夹存在");
                foreach (FileInfo fi in di.GetFiles("*.txt"))
                    Console.WriteLine(@"Copying {0}\{1}", di1.FullName, fi.Name);
                    fi.CopyTo(Path.Combine(di1.ToString(), fi.Name), true);
            //删除archive文件夹,不是空也删除
            di.Delete(true);
            Console.WriteLine(di.Exists);
        catch (Exception e)
            Console.WriteLine("运行出错 {0}", e.ToString());
        finally { }

文件夹存在
Copying G:\Desktop\archive1\MyTest.txt
Copying G:\Desktop\archive1\MyTest1.txt
Copying G:\Desktop\archive1\Test3.txt
False

public static void Main()
        var path1 = "C:/Program Files/";
        var path2 = "Utilities/SystemUtilities";
        ShowPathInformation(path1, path2);
        path1 = "C:/";
        path2 = "/Program Files";
        ShowPathInformation(path1, path2);
        path1 = "C:/Users/Public/Documents/";
        path2 = "C:/Users/User1/Documents/Financial/智能建造小硕公众号.txt";
        ShowPathInformation(path1, path2);
        //以上可在结果中查看Path.Join与Path.Combine的区别
        Console.WriteLine("".PadLeft(60, '-'));
        string path3 = Path.Combine(path1, path2);
        if (Path.HasExtension(path3))
            Console.WriteLine("{0}路径下有扩展{1}", path3, Path.GetExtension(path3));
        if (Path.IsPathRooted(path3))
            Console.WriteLine($" {path3} 有根路径");
        Console.WriteLine("{0}的全路径是 {1}.", path3, Path.GetFullPath(path3));
        Console.WriteLine("{0} 是一个临时路径.", Path.GetTempPath());
        Console.WriteLine("{0}可以被使用.", Path.GetTempFileName());
    private static void ShowPathInformation(string path1, string path2)
        var result = Path.Join(path1.AsSpan(), path2.AsSpan());
        Console.WriteLine($"Concatenating  '{path1}' and '{path2}'");
        Console.WriteLine($"   Path.Join:     '{result}'");
        Console.WriteLine($"   Path.Combine:  '{Path.Combine(path1, path2)}'");

Concatenating  'C:/Program Files/' and 'Utilities/SystemUtilities'
   Path.Join:     'C:/Program Files/Utilities/SystemUtilities'
   Path.Combine:  'C:/Program Files/Utilities/SystemUtilities'
Concatenating  'C:/' and '/Program Files'
   Path.Join:     'C://Program Files'
   Path.Combine:  '/Program Files'
Concatenating  'C:/Users/Public/Documents/' and 'C:/Users/User1/Documents/Financial/智能建造小硕公众号.txt'
   Path.Join:     'C:/Users/Public/Documents/C:/Users/User1/Documents/Financial/智能建造小硕公众号.txt'
   Path.Combine:  'C:/Users/User1/Documents/Financial/智能建造小硕公众号.txt'
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