√ C# - 25.怎么操作文件

1. 操作文件的常用类：File、FileStream、FileInfo等。
2. 操作目录的常用类：Directory、Path等。
3. 一般情况下，使用File类的静态方法即可满足日常需求，包括按行读取写入、按字节读取写入等。
4. 绝对路径的格式：如【D:DesktopFilesfile.txt】。
5. 相对路径的格式：如【……………fileStream.txt】，注意，【…】里面是两个点，CSDN表示不出来！
6. 相对路径中的【…】表示起始目录的上一级目录，比如起始目录是【…CSharpLearn25binDebugnet5.0】，一般情况下，使用5个【…】即可到达项目所在的目录，即【…】。

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;

namespace _25
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("*****测试File类*****");
            TestFile();
            Console.WriteLine();

            Console.WriteLine("*****测试FileStream类*****");
            TestFileStream();
            Console.WriteLine();

            Console.WriteLine("*****测试FileInfo类*****");
            TestFileInfo();
            Console.WriteLine();

            Console.WriteLine("*****测试Directory类*****");
            TestDirectory();
            Console.WriteLine();

            Console.WriteLine("*****测试Path类*****");
            TestPath();
            Console.WriteLine();
        }

        /// 

        /// File类
        /// 
        public static void TestFile()
        {
            //写
            List writeContent = new List();
            writeContent.Add("Test");
            writeContent.Add("File");
            File.WriteAllLines("D:\Desktop\Files\file.txt", writeContent, Encoding.UTF8);

            //读
            string[] readContent = File.ReadAllLines("D:\Desktop\Files\file.txt", Encoding.UTF8);
            for (int i = 0; i < readContent.Length; i++)
            {
                Console.WriteLine(readContent[i]);
            }
        }

        /// 

        /// FileStream类
        /// 
        public static void TestFileStream()
        {
            //写
            FileStream writeStream = new FileStream("..\..\..\..\..\fileStream.txt", FileMode.OpenOrCreate, FileAccess.ReadWrite);
            string writeContent = "TestnFileStream";
            byte[] bytes = Encoding.UTF8.GetBytes(writeContent);
            writeStream.Write(bytes, 0, bytes.Length);
            writeStream.Close();

            //读
            FileStream readStream = new FileStream("..\..\..\..\..\fileStream.txt", FileMode.OpenOrCreate, FileAccess.ReadWrite);
            byte[] readContent = new byte[readStream.Length];
            readStream.Read(readContent, 0, readContent.Length);
            Console.WriteLine(Encoding.UTF8.GetString(readContent));
            readStream.Close();
        }

        /// 

        /// FileInfo类
        /// 
        public static void TestFileInfo()
        {
            FileInfo fileInfo = new FileInfo("D:\Desktop\Files\file.txt");
            Console.WriteLine($"创建时间：{fileInfo.CreationTime}");
            Console.WriteLine($"上一级目录：{fileInfo.DirectoryName}");
            Console.WriteLine($"字节长度：{fileInfo.Length}");
            Console.WriteLine($"绝对路径：{fileInfo.FullName}");
        }

        /// 

        /// Directory类
        /// 
        public static void TestDirectory()
        {
            //判断目录是否存在
            Console.WriteLine(Directory.Exists("D:\Desktop\Files\Directory"));

            //创建目录
            Directory.CreateDirectory("D:\Desktop\Files\Directory");
            Console.WriteLine(Directory.Exists("D:\Desktop\Files\Directory"));

            //删除目录
            Directory.Delete("D:\Desktop\Files\Directory");
            Console.WriteLine(Directory.Exists("D:\Desktop\Files\Directory"));

            //获取目录下的所有文件的绝对路径
            string[] files = Directory.GetFiles("D:\Desktop\Files");
            foreach (var item in files)
            {
                Console.WriteLine(item);
            }
        }

        /// 

        /// Path类
        /// 
        public static void TestPath()
        {
            string filePath = "D:\Desktop\Files\file.txt";
            Console.WriteLine($"绝对路径：{Path.GetFullPath(filePath)}");
            Console.WriteLine($"文件名+后缀名：{Path.GetFileName(filePath)}");
            Console.WriteLine($"文件名：{Path.GetFileNameWithoutExtension(filePath)}");
            Console.WriteLine($"后缀名：{Path.GetExtension(filePath)}");
            Console.WriteLine($"根目录：{Path.GetPathRoot(filePath)}");
            Console.WriteLine($"上一级目录：{Path.GetDirectoryName(filePath)}");
        }
    }
}