3.1 System.IO命名空间
3.1.1 System.IO类介绍
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。
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：
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
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();
}
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
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
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);
}
}
}
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)：
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
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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