文件操作

名称空间：System.IO

浏览文件系统和执行操作的类：
System.MarshalByRefObject  .net中用于远程操作的基对象类，允许在应用程序域之间编组数据
FileSystemInfo 文件系统对象的基类
FileInfo和File 文件系统上的文件
Directory和DirectoryInfo 文件系统上的文件夹
Path 处理路径名
DriveInfo 驱动器的信息

 





递归访问目录和文件：

    string outputText = "";
    int level = -1;
    int indentCount = 0;  //文件夹计数
    int fileCount = 0;    //文件计数
    private string showDirAndFile(DirectoryInfo info)
    {
        level++;

        //输出文件夹信息
        outputText += "<br />" + level;
        for (int i = 0; i < level; i++)
        {
            outputText += "    ";
        }
        outputText = outputText + info.Name;

        //输出文件信息
        FileInfo[] files = info.GetFiles();
        foreach (FileInfo file in files)
        {
            outputText += "<br />" + level;
            for (int i = 0; i < level; i++)
            {
                outputText += "    ";
            }
            outputText = outputText + file.Name;
            fileCount++;
        }

        foreach (DirectoryInfo inf in info.GetDirectories())
        {
            showDir(inf);
            indentCount++;
        }
        level--;
        return outputText;
    }

流：
流是传输数据的对象，数据传输有两个方向：

1. 如果数据从外部源传输到程序中，这是读取流
2. 如果数据是从程序传输到外部源，这是写入流

复制文件：

    int bufferSize = 1024;
    private void Copy(string inputPath, string outputPath)
    {
        Stream inputStream = File.OpenRead(inputPath);
        Stream outputStream = File.OpenWrite(outputPath);

        BufferedStream inputBufferedStream = new BufferedStream(inputStream);
        BufferedStream outputBufferedStream = new BufferedStream(outputStream);

        byte[] buffer = new byte[bufferSize];
        int bytesRead;
        //从流中读取指定个数的字节到字节数据组中，指针移动位置，返回成功读取的字节数
        bytesRead = inputBufferedStream.Read(buffer, 0, bufferSize);
        while (bytesRead != 0) //bytesRead=0 表示读完了
        {
            //将字节数组中的数据写到流中指定位置
            outputBufferedStream.Write(buffer, 0, bufferSize);
            bytesRead = inputBufferedStream.Read(buffer, 0, bufferSize);
        }
        //强制将缓冲区的数据写入文件
        outputBufferedStream.Flush();
        outputBufferedStream.Close();
        inputBufferedStream.Close();
    }

异步读文件：

    byte[] buffer = new byte[1024];
    //char[] chars = new char[1024];
    //IAsyncResult asresult;
    FileStream fs;
    AsyncCallback cb;
    private void AsyncRead1()
    { 
       fs = new FileStream("F:\\1988：我想和这个世界谈谈.txt", FileMode.Open);
       cb = new AsyncCallback(HandleRead);
       fs.BeginRead(buffer, 0, 1024, cb, null);
    }

    private void HandleRead(IAsyncResult ar)
    {
        int rendBytes = fs.EndRead(ar);
        if (rendBytes != 0)
        {
            //Decoder decoder = Encoding.Default.GetDecoder();
            //decoder.GetChars(buffer, 0, 1024, chars, 0);
            //foreach (char i in chars)
            //{
            //    Response.Write(i);
            //}
            string text = Encoding.GetEncoding("GB2312").GetString(buffer, 0, 1024);
            Response.Write(text);
            fs.BeginRead(buffer, 0, buffer.Length, cb, null);
        }       
    }