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 + "
" ;
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 + "
" ;
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 ( ) ;
}
}