C#编程之文件IO

之前我们用c++处理过文件IO管控，这里我们讲一下用c#对文件流的管控。

同样，我们做一个例程，实现文件crc计算，通过打开按钮选择文件，或者通过拖拽方式选择文件。

步骤如下：

1. UI布局
2. XAML:

   <Window x:Class="FileSample.MainWindow"
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
           Title="MainWindow" Height="350" Width="525">
       <Grid>
           <Button Name="myButton" Content=" Open File "  Margin="10,10,0,0" VerticalAlignment="Top" HorizontalAlignment="Left"
                   Click="open_Click"/>
           <TextBox Name="UserInput" Height="100" Margin="10,50,0,0" VerticalAlignment="Top" HorizontalAlignment="Stretch"
                    AllowDrop="True" PreviewDrop="TextBox_PreviewDrop" PreviewDragOver="TextBox_PreviewDragOver" IsReadOnly="True"/>
       </Grid>
   </Window>

3. 因为我们需要用到IO数据流，所以需要使用IO类： using System.IO; 
4. CS：

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Text;
   using System.Threading.Tasks;
   using System.Windows;
   using System.Windows.Controls;
   using System.Windows.Data;
   using System.Windows.Documents;
   using System.Windows.Input;
   using System.Windows.Media;
   using System.Windows.Media.Imaging;
   using System.Windows.Navigation;
   using System.Windows.Shapes;
   using System.IO;
   
   namespace FileSample
   {
       /// <summary>
       /// Interaction logic for MainWindow.xaml
       /// </summary>
       public partial class MainWindow : Window
       {
           UInt16 [] crc_table=new UInt16[256]{
           0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 
           0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 
           0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 
           0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 
           0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, 
           0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, 
           0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, 
           0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 
           0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, 
           0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 
           0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 
           0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 
           0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 
           0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, 
           0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, 
           0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 
           0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, 
           0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, 
           0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 
           0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 
           0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 
           0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 
           0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, 
           0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, 
           0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, 
           0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, 
           0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, 
           0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 
           0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 
           0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 
           0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 
           0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0}; 
           public MainWindow()
           {
               InitializeComponent();
           }
           public UInt16 crc_16(UInt16 crc, byte data)
           {
               byte da;
   
               da = (byte)(crc / 256);
               crc <<= 8;              //crc=crc*256
               crc ^= crc_table[da ^ data];
               return crc;
           }
           private void open_Click(object sender, RoutedEventArgs e)
           {
               System.Windows.Forms.OpenFileDialog openfile = new System.Windows.Forms.OpenFileDialog();
               UInt16 crc;
               openfile.InitialDirectory = "D:\";
               openfile.Filter = "txt files |*.txt|All files |*.*";
               openfile.FilterIndex = 1;
               openfile.RestoreDirectory = true;
               if(openfile.ShowDialog()==System.Windows.Forms.DialogResult.OK)
               {
                   UserInput.Text = openfile.FileName + "
   ";
                   StreamReader sr = new System.IO.StreamReader(openfile.FileName, Encoding.Default);
                   crc = 0xffff;
                   while(sr.Peek() > 0)
                   {
                       //UserInput.Text += (char)sr.Read();
                       crc = crc_16(crc, (byte)sr.Read());
                   }
                   UserInput.Text += "crc=" + Convert.ToString(crc) + "
   ";
               }
           }
   
           private void TextBox_PreviewDrop(object sender, DragEventArgs e)
           {
               UInt16 crc;
               //get files counter
               Array fileArray = (System.Array)e.Data.GetData(DataFormats.FileDrop);
               UserInput.Text = "";
               string filePath;
               for (int i=0; i < fileArray.Length; i++)
               {
                   filePath = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(i).ToString();
                   UserInput.Text += filePath + "
   ";
                   StreamReader sr=new System.IO.StreamReader(filePath,Encoding.Default);
                   crc = 0xffff;
                   while(sr.Peek()>0)
                   {
                       crc = crc_16(crc, (byte)sr.Read());
                   }
                   UserInput.Text += "crc=" + Convert.ToString(crc) + "
   ";
               }
           }
   
           private void TextBox_PreviewDragOver(object sender, DragEventArgs e)
           {
               if (e.Data.GetDataPresent(DataFormats.FileDrop))
               {
                   e.Effects = DragDropEffects.Link;
                   e.Handled = true;
               }
               else
                   e.Effects = DragDropEffects.None;
           }
       }
   }

5. 编译运行。

End.