c# Stream to File的知识点

个人倾向使用File.WriteAllByte写入文件：

//Stream to File
MemoryStream ms=...Stream;
ms.Position = ;
byte[] buffer = new byte[ms.Length];
ms.Read(buffer, , (int)ms.Length);
File.WriteAllBytes(filepath, buffer);//写入文件

StreamRead,StreamWrite,SreamRead,以及File的部分操作

// StreamRead,StreamWrite,File只能操作文本文件 
//FileStream可以操作所有格式 包括文本，文件，图片，视频
//SreamRead读取文件
using (StreamReader reader = new StreamReader(filepath))
 {
        //reader.ReadLine();读取第一行
        string data = reader.ReadToEnd();//读取所有
 }
//StreamWrite写入文件
 using (StreamWriter writer = new StreamWriter(filepath))
 {
         //writer.Write("写入的内容");
         //也可以如下面一行一行写入
         writer.WriteLine("");
         writer.WriteLine("");
         writer.WriteLine(picName);
         writer.WriteLine(txtCount.Text);
 }  

//File即可以读取文本 也可以写入文本
//读取
string data = File.ReadAllText(filepath);
string[] datas = File.ReadAllLines(filepath);
//写入
string[] ss = new string[] {"arr1","arr2" };
File.WriteAllLines(filepath, ss);
File.WriteAllText(filepath, "\r\n换行\r\n"); 
//附加
File.AppendAllLines(filepath,ss);
File.AppendAllText(filepath,str); 

//FileStream可以操作所有格式 包括文本，文件，图片，视频
//FileStream读取
string ss = null;
byte[] buffer = new byte[ *  * ];  //针对大文件1M1M的读取
 using (FileStream sr = new FileStream(sfilepath, FileMode.OpenOrCreate, FileAccess.Read))
 {
    int sss = sr.Read(buffer, , buffer.Length);
    ss = Encoding.Default.GetString(buffer, , sss);
 }
//FileStream写入
using (FileStream fsWrite = new FileStream(filepath, FileMode.OpenOrCreate, FileAccess.Write))
{
    byte[] buffer = Encoding.Default.GetBytes(str);
    fsWrite.Write(buffer, , buffer.Length);
}

Stream 和 File 之间的转换

/// <summary>
/// 将 Stream 写入文件
/// </summary>
public void StreamToFile(Stream stream,string filepath)
{
    // 把 Stream 转换成 byte[]
    byte[] bytes = new byte[stream.Length];
    stream.Read(bytes, , bytes.Length);
    // 设置当前流的位置为流的开始
    stream.Seek(, SeekOrigin.Begin);
    // 把 byte[] 写入文件
    FileStream fs = new FileStream(filepath, FileMode.Create);
    BinaryWriter bw = new BinaryWriter(fs);
    bw.Write(bytes);
    bw.Close();
    fs.Close();
}
/// <summary>
/// 从文件读取 Stream
/// </summary>
public Stream FileToStream(string filepath)
{
    // 打开文件
    FileStream fileStream = new FileStream(filepath, FileMode.Open, FileAccess.Read, FileShare.Read);
    // 读取文件的 byte[]
    byte[] bytes = new byte[fileStream.Length];
    fileStream.Read(bytes, , bytes.Length);
    fileStream.Close();
    // 把 byte[] 转换成 Stream
    Stream stream = new MemoryStream(bytes);
    return stream;
}  

文件复制（当然File.Copy更常用，这个是偶然中使用到整理的）

public static void CopyFile(string soucre, string target)
        {
            //读取的流
            using (FileStream fsRead = new FileStream(soucre, FileMode.Open, FileAccess.Read))
            {
                //写入的流
                using (FileStream fsWrite = new FileStream(target, FileMode.OpenOrCreate, FileAccess.Write))
                {
                    byte[] buffer = new byte[ *  * ];
                    while (true)
                    {
                        int r = fsRead.Read(buffer, , buffer.Length);
                        //0代表已经读取完
                        if (r == )
                        {
                            break;
                        }
                        fsWrite.Write(buffer, , r);
                    }
                }
            }
        }