C# 流

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;

//流
namespace Stream
{
    class Program
    {
        static void Main(string[] args)
        {
            Stream2();
            Console.ReadKey();
        }

        static void Stream1()
        {
            string filePath = "D:\\test.txt";
            //利用File.Open创建一个FileStream实体
            using (FileStream filestream = File.Open(filePath, FileMode.Open))
            {
                //定义字符串
                string msg = "hello world";//string msg =Console.ReadLine();
                //将字符串转化为字节数据
                byte[] msgAsByteArray = Encoding.Default.GetBytes(msg);
                Console.WriteLine("开始写入到文件中{0}", msg);
                //将字节数据写入到流中
                filestream.Write(msgAsByteArray, 0, msgAsByteArray.Length);
                //重置流中的位置
                filestream.Seek(0, SeekOrigin.Begin);
                Console.WriteLine("写入文件中的数据为:");
                //定义字节数组
                byte[] bytesFormFile = new byte[msgAsByteArray.Length];
                //从流中读取到字节数据
                filestream.Read(bytesFormFile, 0, msgAsByteArray.Length);
                Console.WriteLine(Encoding.Default.GetString(bytesFormFile));

            }
        }
        /// <summary>
        /// StreamWriter与StreamReader
        /// </summary>
        static void Stream2()
        {
            string filePath = "D:\\test.txt";
            using (FileStream filestream = File.Open(filePath, FileMode.Open))
            {
                //定义字符串
                string msg = "hello world(你好)";//string msg =Console.ReadLine();
                //创建StreamWriter对象System.Text.Encoding.Default:编码格式
                StreamWriter streamwriter = new StreamWriter(filestream,System.Text.Encoding.Default);
                Console.WriteLine("开始写入{0}到文件中", msg);
                streamwriter.Write(msg);
                //创建StreamReader对象
                StreamReader streamreader = new StreamReader(filestream, Encoding.Default);
                //这里将读不到数据，因为还未写入完成
                Console.WriteLine("写入到文件中数据为{0}", streamreader.ReadToEnd());
                //关闭
                streamwriter.Close();
                streamreader.Close();
            }
        }
    }
}

Stream继承结构: