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:
   

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

   View Code
3. 因为我们需要用到IO数据流，所以需要使用IO类： 1 using System.IO; 
4. CS：
   

     1 using System;
     2 using System.Collections.Generic;
     3 using System.Linq;
     4 using System.Text;
     5 using System.Threading.Tasks;
     6 using System.Windows;
     7 using System.Windows.Controls;
     8 using System.Windows.Data;
     9 using System.Windows.Documents;
    10 using System.Windows.Input;
    11 using System.Windows.Media;
    12 using System.Windows.Media.Imaging;
    13 using System.Windows.Navigation;
    14 using System.Windows.Shapes;
    15 using System.IO;
    16 
    17 namespace FileSample
    18 {
    19     /// <summary>
    20     /// Interaction logic for MainWindow.xaml
    21     /// </summary>
    22     public partial class MainWindow : Window
    23     {
    24         UInt16 [] crc_table=new UInt16[256]{
    25         0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7, 
    26         0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef, 
    27         0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6, 
    28         0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de, 
    29         0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485, 
    30         0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d, 
    31         0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4, 
    32         0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc, 
    33         0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823, 
    34         0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b, 
    35         0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12, 
    36         0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a, 
    37         0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41, 
    38         0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49, 
    39         0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70, 
    40         0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78, 
    41         0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f, 
    42         0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067, 
    43         0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e, 
    44         0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256, 
    45         0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d, 
    46         0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405, 
    47         0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c, 
    48         0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634, 
    49         0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab, 
    50         0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3, 
    51         0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a, 
    52         0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92, 
    53         0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9, 
    54         0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1, 
    55         0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8, 
    56         0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0}; 
    57         public MainWindow()
    58         {
    59             InitializeComponent();
    60         }
    61         public UInt16 crc_16(UInt16 crc, byte data)
    62         {
    63             byte da;
    64 
    65             da = (byte)(crc / 256);
    66             crc <<= 8;              //crc=crc*256
    67             crc ^= crc_table[da ^ data];
    68             return crc;
    69         }
    70         private void open_Click(object sender, RoutedEventArgs e)
    71         {
    72             System.Windows.Forms.OpenFileDialog openfile = new System.Windows.Forms.OpenFileDialog();
    73             UInt16 crc;
    74             openfile.InitialDirectory = "D:\\";
    75             openfile.Filter = "txt files |*.txt|All files |*.*";
    76             openfile.FilterIndex = 1;
    77             openfile.RestoreDirectory = true;
    78             if(openfile.ShowDialog()==System.Windows.Forms.DialogResult.OK)
    79             {
    80                 UserInput.Text = openfile.FileName + "\r\n";
    81                 StreamReader sr = new System.IO.StreamReader(openfile.FileName, Encoding.Default);
    82                 crc = 0xffff;
    83                 while(sr.Peek() > 0)
    84                 {
    85                     //UserInput.Text += (char)sr.Read();
    86                     crc = crc_16(crc, (byte)sr.Read());
    87                 }
    88                 UserInput.Text += "crc=" + Convert.ToString(crc) + "\r\n";
    89             }
    90         }
    91 
    92         private void TextBox_PreviewDrop(object sender, DragEventArgs e)
    93         {
    94             UInt16 crc;
    95             //get files counter
    96             Array fileArray = (System.Array)e.Data.GetData(DataFormats.FileDrop);
    97             UserInput.Text = "";
    98             string filePath;
    99             for (int i=0; i < fileArray.Length; i++)
   100             {
   101                 filePath = ((System.Array)e.Data.GetData(DataFormats.FileDrop)).GetValue(i).ToString();
   102                 UserInput.Text += filePath + "\r\n";
   103                 StreamReader sr=new System.IO.StreamReader(filePath,Encoding.Default);
   104                 crc = 0xffff;
   105                 while(sr.Peek()>0)
   106                 {
   107                     crc = crc_16(crc, (byte)sr.Read());
   108                 }
   109                 UserInput.Text += "crc=" + Convert.ToString(crc) + "\r\n";
   110             }
   111         }
   112 
   113         private void TextBox_PreviewDragOver(object sender, DragEventArgs e)
   114         {
   115             if (e.Data.GetDataPresent(DataFormats.FileDrop))
   116             {
   117                 e.Effects = DragDropEffects.Link;
   118                 e.Handled = true;
   119             }
   120             else
   121                 e.Effects = DragDropEffects.None;
   122         }
   123     }
   124 }

   View Code
5. 编译运行。

End.