概念
编码
将字符序列转化为字节序列的过程
数据流
输入设备和输出设备的数据传递
Encoding类
using System.Text;
Encoding.GetEncodings() //返回一个数组
编码实例
using System;
using System.Text;
namespace _20200330
{
class Program
{
static void Main(string[] args)
{
foreach (var i in Encoding.GetEncodings())
{
Encoding en1 = i.GetEncoding();
Console.WriteLine("编码名称:{0,-18},编码描述:{1}",i.Name,en1.EncodingName);
}
string s1;
s1=Console.ReadLine();
Encoding en = Encoding.ASCII;
byte[] bytes = en.GetBytes(s1);
Console.WriteLine(BitConverter.ToString(bytes));
Encoding en2 = Encoding.Unicode;
byte[] bytes1 = en2.GetBytes(s1);
Console.WriteLine(BitConverter.ToString(bytes1));
}
}
}
文件的读取实例
FileStream类
FileStream类可以对各种类型的文件进行读写操作
using System;
using System.IO;//关键命名空间
using System.Text;
namespace 20200331
{
class Program
{
static void Main(string[] args)
{
//FileStream fs =new FileStream(string path,FileMode mode,FileAccess access);
// path指定文件路径，mode指定文件操作方式，access控制文件访问权限
FileStream fs =new FileStream("1.txt",FileMode.OpenOrCreate,FileAccess.ReadWrite);//构造一个文件流
//在Debug目录下新建一个1.txt
FileStream fs2 =new FileStream("2.txt",FileMode.Create,FileAccess.ReadWrite);//构造另一个文件流
byte[] buffer= new byte[1024];//构造缓冲区
int num =fs.Read(buffer,0,buffer.Length);//从0位置开始读取buffer.length长度,将文件实际读取的长度赋给mum
fs2.Write(buffer,0,num);//将缓冲区中的数据流写入另一文件//此时文件位指针fs2.Position不断后移,文件的读取从指针指向的位置进行,每次读取之前需要改变指针位置
fs2.Close();
String str =Encoding.UTF8.GetString(buffer,0,num);//将buffer从0位置开始解码mum个位置
fs.Close();//关闭文件
Console.WriteLine(str);
}
}
}
StreamReader和StreamWriter类
只能操作文本
using System;
using System.IO;
using System.Text;
namespace 20200407
{
class Program
{
static void Main(string[] args)
{
FileStream fs = new FileStream("1.txt",FileMode.Open,FileAccess.Read);//构造一个文件流
StreamReader sr= new StreamReader(fs);//操作sr相当于操作fs
String str=sr.ReadToEnd();//全部读取
fs.Close();
sr.Close();
}
}
}
Aes类
加密流 CryptoStream
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
public static byte[] EncryptString(string str, byte[] key, byte[] iv)
{
byte[] encrypted;
using (Aes aesAlg = Aes.Create())//此时已经自动创建了key和iv
{
ICryptoTransform encryptor = aesAlg.CreateEncryptor(key, iv);//key是密钥,iv是初始化向量，一个随机生成的字符集
//明文按块加密，每一块和前一块进行按位异或操作，第一块与iv进行按位异或
MemoryStream ms = new MemoryStream(); //内存流
//CryptoStream cs = new CryptoStream(Stream stream,ICryptoTransform transform,CryptoStreamMode mode);
// 加密或解密后的目的流 加密转换的方式 模式，解密读取，加密写入
CryptoStream cs = new CryptoStream(ms,encryptor,CryptoStreamMode.Write);
//byte[] oldBytes= Encoding.UTF8.GetBytes(str);
//cs.Write(oldBytes, 0, oldBytes.Length);
using (StreamWriter sw = new StreamWriter(cs))//
{
sw.Write(str);
}
encrypted = ms.ToArray();
cs.Close();
ms.Close();
}
return encrypted;
}
/// <summary>
使用AES算法解密字符串
///</summary>
public static string DescrptString(byte[] data, byte[] key, byte[] iv)
{
string str = null;
using (Aes aesAlg = Aes.Create())
{
ICryptoTransform decryptor = aesAlg.CreateDecryptor(key, iv);
MemoryStream ms = new MemoryStream(data);
CryptoStream cs = new CryptoStream(ms,decryptor,CryptoStreamMode.Read);
using (StreamReader sr = new StreamReader(cs))
{
str = sr.ReadToEnd();
}
cs.Close();
ms.Close();
}
return str;
}
/// <summary>根据提供的密码生成Key和IV</summary>
public static void GenKeyIV(string password, out byte[] key, out byte[] iv)//返回多个值,key数组和iv数组
{
using (Aes aes = Aes.Create())
{
key = new byte[aes.Key.Length]; //创建密钥空间
byte[] pwdBytes = Encoding.UTF8.GetBytes(password);//获得密码的UTF-8编码,存储到pwdBytes数组中，若密码数据长度不够，还可以补全
for (int i = 0; i < pwdBytes.Length; i++)
{
key[i] = pwdBytes[i]; //将pwdBytes数组中的数据赋给key数组
}
iv = new byte[aes.IV.Length];
for (int i = 0; i < pwdBytes.Length; i++)
{
iv[i] = pwdBytes[i];
}
}
}
/// <summary>根据提供的密码生成Key和IV</summary>
public static void GenKeyIV(out byte[] key, out byte[] iv)//没有密码的情况直接赋值
{
using (Aes aes = Aes.Create())
{
key = aes.Key;
iv = aes.IV;
}
}