以下是代码片段：
如何读取文本文件内容： 在本文介绍的程序中，是把读取的文本文件，用一个richTextBox组件显示出来。要读取文本文件，必须使用到"StreamReader"类，这个类是由名字空间"System.IO"中定义的。通过"StreamReader"类的"ReadLine ( )"方法，就可以读取打开数据流当前行的数据了。下面代码实现的功能就是读取"C:\file.txt"并在richTextBox1组件中显示出来： FileStream fs = new FileStream ( "C:\\file.txt" , FileMode.Open , FileAccess.Read ) ; StreamReader m_streamReader = new StreamReader ( fs ) ; //使用StreamReader类来读取文件 m_streamReader.BaseStream.Seek ( 0 , SeekOrigin.Begin ) ; // 从数据流中读取每一行，直到文件的最后一行，并在richTextBox1中显示出内容 this.richTextBox1.Text = "" ; string strLine = m_streamReader.ReadLine ( ) ; while ( strLine != null ) { this.richTextBox1.Text += strLine + "\n" ; strLine = m_streamReader.ReadLine ( ) ; } //关闭此StreamReader对象 m_streamReader.Close ( ) ; 如何改变文本文件中数据内容： 在本文介绍的程序中，改变文本文件数据内容的功能是通过改变richTextBox1中的内容来实现的，当richTextBox1这的内容改变后，按动"另存为"，就把richTextBox1中内容存储到指定的文本文件中了。要想改变文本文件内容，要使用到"StreamWriter"类，这个类和"StreamReader"一样，都是由"System.IO"名字空间来定义的。通过"StreamWriter"类的"Write ( )"方法，就可以轻松实现文本文件内容的更改了。下面代码的功能是：如果"C"盘存在"file.txt"，则把richTextBox1中的内容写入到"file.txt"中，如果不存在，则创建此文件，然后在写入文本数据。 //创建一个文件流，用以写入或者创建一个StreamWriter FileStream fs = new FileStream ( "C\\file.txt" , FileMode.OpenOrCreate , FileAccess.Write ) ; StreamWriter m_streamWriter = new StreamWriter ( fs ) ; m_streamWriter.Flush ( ) ; // 使用StreamWriter来往文件中写入内容 m_streamWriter.BaseStream.Seek ( 0 , SeekOrigin.Begin ) ; // 把richTextBox1中的内容写入文件 m_streamWriter.Write ( richTextBox1.Text ) ; //关闭此文件 m_streamWriter.Flush ( ) ; m_streamWriter.Close ( ) ; 如何实现打印预览： 打印预览是通过打印预览对话框来实现的，实现对读取得文本文件的打印预览，最为重要的就是要通知打印预览对话框所要预览的文件的内容。下面代码就是把richTextBox1中显示的内容，通过打印预览对话框显示出来： //www.naio.net string strText = richTextBox1.Text ; StringReader myReader = new StringReader ( strText ) ; PrintPreviewDialog printPreviewDialog1 = new PrintPreviewDialog ( ) ; printPreviewDialog1.Document = ThePrintDocument ; printPreviewDialog1.FormBorderStyle = FormBorderStyle.Fixed3D ; printPreviewDialog1.ShowDialog ( ) ; 下列代码是设定打印内容即打印richTextBox1中的内容： float linesPerPage = 0 ; float yPosition = 0 ; int count = 0 ; float leftMargin = ev.MarginBounds.Left ; float topMargin = ev.MarginBounds.Top ; string line = null ; Font printFont = richTextBox1.Font ; SolidBrush myBrush = new SolidBrush ( Color.Black ) ; //计算每一页打印多少行 linesPerPage = ev.MarginBounds.Height / printFont.GetHeight ( ev.Graphics ) ; //重复使用StringReader对象 ,打印出richTextBox1中的所有内容 while ( count < linesPerPage && ( ( line = myReader.ReadLine ( ) ) != null ) ) { // 计算出要打印的下一行所基于页面的位置 yPosition = topMargin + ( count * printFont.GetHeight ( ev.Graphics ) ) ; // 打印出richTextBox1中的下一行内容 ev.Graphics.DrawString ( line , printFont , myBrush , leftMargin , yPosition , new StringFormat ( ) ) ; count++ ; } // 判断如果还要下一页，则继续打印 if ( line != null ) ev.HasMorePages = true ; else ev.HasMorePages = false ; myBrush.Dispose ( ) ; using System ; using System.Drawing ; using System.Collections ; using System.ComponentModel ; using System.Windows.Forms ; using System.Data ; using System.IO ; using System.Drawing.Printing ; public class Form1 : Form { private RichTextBox richTextBox1 ; private Button button1 ; private Button button2 ; private Button button3 ; private Button button4 ; private Button button5 ; private OpenFileDialog openFileDialog1 ; private SaveFileDialog saveFileDialog1 ; private PrintDialog printDialog1 ; private PrintDocument ThePrintDocument ; private PrintPreviewDialog printPreviewDialog1 ; private StringReader myReader ; private System.ComponentModel.Container components = null ; public Form1 ( ) { //初始化窗体中的各个组件 InitializeComponent ( ) ; } //清除程序中使用多的资源 protected override void Dispose ( bool disposing ) { if ( disposing ) { if ( components != null ) { components.Dispose ( ) ; } } base.Dispose ( disposing ) ; } private void InitializeComponent ( ) { richTextBox1 = new RichTextBox ( ) ; button1 = new Button ( ) ; button2 = new Button ( ) ; button3 = new Button ( ) ; button4 = new Button ( ) ; button5 = new Button ( ) ; saveFileDialog1 = new SaveFileDialog ( ) ; openFileDialog1 = new OpenFileDialog ( ) ; printPreviewDialog1 = new PrintPreviewDialog ( ) ; printDialog1 = new PrintDialog ( ) ; ThePrintDocument = new PrintDocument ( ) ; ThePrintDocument.PrintPage += new PrintPageEventHandler ( ThePrintDocument_PrintPage ) ; SuspendLayout ( ) ; richTextBox1.Anchor = AnchorStyles.None ; richTextBox1.Name = "richTextBox1" ; richTextBox1.Size = new Size ( 448 , 280 ) ; richTextBox1.TabIndex = 0 ; richTextBox1.Text = "" ; button1.Anchor = AnchorStyles.None ; button1.Location = new Point ( 41 , 289 ) ; button1.Name = "button1" ; button1.Size = new Size ( 48 , 30 ) ; button1.TabIndex = 1 ; button1.Text = "打开" ; button1.Click += new System.EventHandler ( button1_Click ) ; button2.Anchor = AnchorStyles.None ; button2.Location = new Point ( 274 , 288 ) ; button2.Name = "button2" ; button2.Size = new Size ( 48 , 30 ) ; button2.TabIndex = 4 ; button2.Text = "预览" ; button2.Click += new System.EventHandler ( button2_Click ) ; button3.Anchor = AnchorStyles.None ; button3.Location = new Point ( 108 , 288 ) ; button3.Name = "button3" ; button3.Size = new Size ( 48 , 30 ) ; button3.TabIndex = 2 ; button3.Text = "保存" ; button3.Click += new System.EventHandler ( button3_Click ) ; button4.Anchor = AnchorStyles.None ; button4.Location = new Point ( 174 , 288 ) ; button4.Name = "button4" ; button4.Size = new Size ( 80 , 30 ) ; button4.TabIndex = 3 ; button4.Text = "打印机设置" ; button4.Click += new System.EventHandler ( button4_Click ) ; button5.Anchor = AnchorStyles.None ; button5.Location = new Point ( 345 , 288 ) ; button5.Name = "button5" ; button5.Size = new Size ( 48 , 30 ) ; button5.TabIndex = 5 ; button5.Text = "打印" ; button5.Click += new System.EventHandler ( button5_Click ) ; saveFileDialog1.DefaultExt = "*.txt" ; saveFileDialog1.FileName = "file.txt" ; saveFileDialog1.InitialDirectory = "c:\\" ; saveFileDialog1.Title = "另存为！" ; openFileDialog1.DefaultExt = "*.txt" ; openFileDialog1.FileName = "file.txt" ; openFileDialog1.InitialDirectory = "c:\\" ; openFileDialog1.Title = "打开文本文件！" ; AutoScaleBaseSize = new Size ( 6 , 14 ) ; ClientSize = new Size ( 448 , 325 ) ; this.Controls.Add ( button1 ) ; this.Controls.Add ( button2 ) ; this.Controls.Add ( button3 ) ; this.Controls.Add ( button4 ) ; this.Controls.Add ( button5 ) ; this.Controls.Add ( richTextBox1 ) ; this.MaximizeBox = false ; this.Name = "Form1" ; this.Text = "C＃来操作文本文件" ; this.ResumeLayout ( false ) ; } static void Main ( ) { Application.Run ( new Form1 ( ) ) ; } private void button1_Click ( object sender , System.EventArgs e ) { try { if ( openFileDialog1.ShowDialog ( ) == DialogResult.OK ) { FileStream fs = new FileStream ( openFileDialog1.FileName , FileMode.Open , FileAccess.Read ) ; StreamReader m_streamReader = new StreamReader ( fs ) ; //使用StreamReader类来读取文件 m_streamReader.BaseStream.Seek ( 0 , SeekOrigin.Begin ) ; // 从数据流中读取每一行，直到文件的最后一行，并在richTextBox1中显示出内容 this.richTextBox1.Text = "" ; string strLine = m_streamReader.ReadLine ( ) ; while ( strLine != null ) { this.richTextBox1.Text += strLine + "\n" ; strLine = m_streamReader.ReadLine ( ) ; } //关闭此StreamReader对象 m_streamReader.Close ( ) ; } } catch ( Exception em ) { Console.WriteLine ( em.Message.ToString ( ) ) ; } } private void button3_Click ( object sender , System.EventArgs e ) { try { //获得另存为的文件名称 if ( saveFileDialog1.ShowDialog ( ) == DialogResult.OK ) { //创建一个文件流，用以写入或者创建一个StreamWriter FileStream fs = new FileStream ( @saveFileDialog1.FileName , FileMode.OpenOrCreate , FileAccess.Write ) ; StreamWriter m_streamWriter = new StreamWriter ( fs ) ; m_streamWriter.Flush ( ) ; // 使用StreamWriter来往文件中写入内容 m_streamWriter.BaseStream.Seek ( 0 , SeekOrigin.Begin ) ; // 把richTextBox1中的内容写入文件 m_streamWriter.Write ( richTextBox1.Text ) ; //关闭此文件 m_streamWriter.Flush ( ) ; m_streamWriter.Close ( ) ; } } catch ( Exception em ) { Console.WriteLine ( em.Message.ToString ( ) ) ; } } private void button4_Click ( object sender , System.EventArgs e ) { printDialog1.Document = ThePrintDocument ; printDialog1.ShowDialog ( ) ; } //预览打印文档 private void button2_Click ( object sender , System.EventArgs e ) { try { string strText = richTextBox1.Text ; myReader = new StringReader ( strText ) ; PrintPreviewDialog printPreviewDialog1 = new PrintPreviewDialog ( ) ; printPreviewDialog1.Document = ThePrintDocument ; printPreviewDialog1.FormBorderStyle = FormBorderStyle.Fixed3D ; printPreviewDialog1.ShowDialog ( ) ; } catch ( Exception exp ) { Console.WriteLine ( exp.Message.ToString ( ) ) ; } } //打印richTextBox1中的内容 private void button5_Click ( object sender , System.EventArgs e ) { printDialog1.Document = ThePrintDocument ; string strText = richTextBox1.Text ; myReader = new StringReader ( strText ) ; if ( printDialog1.ShowDialog ( ) == DialogResult.OK ) { ThePrintDocument.Print ( ) ; } } protected void ThePrintDocument_PrintPage ( object sender , PrintPageEventArgs ev ) { float linesPerPage = 0 ; float yPosition = 0 ; int count = 0 ; float leftMargin = ev.MarginBounds.Left ; float topMargin = ev.MarginBounds.Top ; string line = null ; Font printFont = richTextBox1.Font ; SolidBrush myBrush = new SolidBrush ( Color.Black ) ; //计算每一页打印多少行 linesPerPage = ev.MarginBounds.Height / printFont.GetHeight ( ev.Graphics ) ; //重复使用StringReader对象 ,打印出richTextBox1中的所有内容 while ( count < linesPerPage && ( ( line = myReader.ReadLine ( ) ) != null ) ) { // 计算出要打印的下一行所基于页面的位置 yPosition = topMargin + ( count * printFont.GetHeight ( ev.Graphics ) ) ; // 打印出richTextBox1中的下一行内容 ev.Graphics.DrawString ( line , printFont , myBrush , leftMargin , yPosition , new StringFormat ( ) ) ; count++ ; } // 判断如果还要下一页，则继续打印 if ( line != null ) ev.HasMorePages = true ; else ev.HasMorePages = false ; myBrush.Dispose ( ) ; } } | 
