C# WinForm实践开发教程——第三章文件处理技术

清疚 2021-06-24 16:11 457阅读 0赞

#### 3.1 System.IO命名空间 ####

###### 3.1.1 System.IO类介绍 ######

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###### 3.1.2 File类的常用方法 ######

File类提供用于创建、复制、删除、移动和打开文件的静态方法，并协助创建FileStream对象。

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小练习：

using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    
    namespace FileTest
    {
        class Program
        {
            static void Main(string[] args)
            {
                string path = @"D:\\Test.txt";
                if (!File.Exists(path))
                { 
                    //创建文件，以便写入内容
                    using (StreamWriter sw = File.CreateText(path))
                    {
                        List<string> ls_string = new List<string> {"a","b","c","d","e","f","g","h","i","j","k","l" };
                        foreach (var tes in ls_string)
                        {
                            sw.Write(tes);
                        }
    
                        foreach (var tes in ls_string)
                        {
                            sw.WriteAsync(tes);
                        }
                    }
                }
    
                //打开文件，从中读取数据
                using (StreamReader sr = File.OpenText(path))
                {
                    string s = "";
                    while ((s = sr.ReadLine()) != null)
                    {
                        Console.WriteLine(s);
                    }
                }
    
                try
                {
                    //删除复制
                    string path2 = "PathTwo.txt";
                    File.Delete(path2);
                    File.Copy(path, path2);
                    File.Delete(path);
                }
                catch (Exception ex)
                {
                    Console.WriteLine("{0}", ex.ToString());
                }
    
                Console.ReadLine();
            }
    
        }
    }

###### 3.1.3 FileInfo类的常用方法 ######

FileInfo类提供创建、复制、删除、移动和打开文件的实例方法，并且帮助创建FileStream对象。FileInfo类无法继承。FileInfo类有几个常用属性，如下：

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static void Main(string[] args)
            {
                string path = @"D:\\Test.txt";
                FileInfo fileInfo = new FileInfo(path);
                if (!fileInfo.Exists)
                {
                    return;
                }
                Console.WriteLine("{0} has a directoryName of {1}",path,fileInfo.DirectoryName);
    
                Console.ReadLine();
            }

###### 3.1.4 文件夹类Directory的常用方法 ######

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static void Main(string[] args)
            {
                //获取当前目录的创建时间
                DateTime dt2 = Directory.GetCreationTime(Environment.CurrentDirectory);
                DateTimeOffset dt3 = Directory.GetCreationTime(Environment.CurrentDirectory);
    
                Console.WriteLine("当前目录时间：{0}，时间：{1}",dt2,dt3);
    
                var files = Directory.GetFiles(Environment.CurrentDirectory);
    
                var name = files[0].ToString();
    
                Console.WriteLine("第一个文件：{0}",name.Split('\\').Last());
    
                Console.ReadLine();
            }

![2789632-2c1c5a862f38b716.png][]

#### 3.2 文件流类FileStream ####

FileStream对象也称为文件流对象，它为文件的读写操作提供通道，而File对象相当于提供一个文件句柄。在文件操作中，针对FileStream对象的操作必须首先实例化一个FileStream类对象后才可以进行，这一点与File类的操作是不一样的。

FileStream mikecatstream;
                mikecatstream = File.Create(Environment.CurrentDirectory + "\\test.txt");
                //本段代码的含义：
                //利用File类的Create()方法在当前目录创建test.txt,并把文件流赋给mikecatstream

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#### 3.3 读写二进制文件 ####

###### 3.3.1 二进制文件读取器（BinaryReader）/编写器（BinaryWriter）介绍 ######

![2789632-240d9b4002502f6d.png][]

示例：

using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;
    
    namespace BinaryTest
    {
        class Program
        {
            static void Main(string[] args)
            {
                int i = 0;
                char[] invalidPathChars = Path.InvalidPathChars;
                MemoryStream memStream = new MemoryStream();
                BinaryWriter binWriter = new BinaryWriter(memStream);
                //写入内存
                binWriter.Write("Invalid file path characers are:");
                for (i = 0; i < invalidPathChars.Length; i++)
                {
                    binWriter.Write(invalidPathChars[i]);
                }
                //用作生成编写器的内存流同样作为生成读取器的内存流
                BinaryReader binReader = new BinaryReader(memStream);
                //设置流的起点
                memStream.Position = 0;
                //从内存中读取数据，并把数据写入控制台
                Console.Write(binReader.ReadString());
                char[] memoryData = new char[memStream.Length - memStream.Position];
                for (i = 0; i < memoryData.Length; i++)
                {
                    memoryData[i] = Convert.ToChar(binReader.Read());
                }
                Console.WriteLine(memoryData);
            }
        }
    }

![2789632-53ed522fd2c9016b.png][]

突然想起来大一学c语言用里面的c%画的心形，哈哈，趁此再来一波(在上面的代码里加以改动)：

![2789632-411022386b9f6d7a.png][]

using System;
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Text;
    using System.Threading;
    using System.Threading.Tasks;
    
    namespace BinaryTest
    {
        class Program
        {
            static void Main(string[] args)
            {
                int i = 0;
                char[] invalidPathChars = Path.InvalidPathChars;
                MemoryStream memStream = new MemoryStream();
                BinaryWriter binWriter = new BinaryWriter(memStream);
                //写入内存
                binWriter.Write("Invalid file path characers are:");
                for (i = 0; i < invalidPathChars.Length; i++)
                {
                    binWriter.Write(invalidPathChars[i]);
                }
                //用作生成编写器的内存流同样作为生成读取器的内存流
                BinaryReader binReader = new BinaryReader(memStream);
                //设置流的起点
                memStream.Position = 0;
                //从内存中读取数据，并把数据写入控制台
                //Console.Write(binReader.ReadString());
                char[] memoryData = new char[memStream.Length - memStream.Position];
                for (i = 0; i < memoryData.Length; i++)
                {
                    memoryData[i] = Convert.ToChar(binReader.Read());
                }
                //Console.WriteLine(memoryData);
    
                while(true)
                {
                    List<int> x = new List<int> { 5,6,7,8,9,10,11,12};
                    int index = new Random().Next(x.Count);
                    PrintLove(memoryData, x[index]);
                    Thread.Sleep(1000);
                    Console.Clear();
                }
            }
    
            private static void PrintLove(char[] memoryData,int i)
            {
                for (float y = 1.3f; y >= -1.1f; y -= 0.06f)
                {
                    for (float x = -1.2f; x <= 1.2; x += 0.025f)
                    {
                        if (Math.Pow((x * x + y * y - 1.0), 3) - x * x * y * y * y <= 0.0)
                            Console.Write(" ");
                        else
                            Console.Write(memoryData[i]);
                    }
                    Console.WriteLine();
                }  
            }
        }
    }

#### 3.4 读写内存流 ####

###### 3.4.1 读写内存流——MemoryStream类 ######

![2789632-29c44da72278233b.png][]

关于内存流对象中重要的属性：  
Length属性代表了内存流对象存放的数据的真是长度，而Capacity属性则代表了分配给内存流的内存空间大小。

###### 3.4.2 读写缓存流——BufferenStream类 ######

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