问使用c#将txt打印到默认打印机

EN

using System;
using System.Drawing;
using System.Drawing.Printing;
using System.Windows.Forms;
using System.IO;
using System.Runtime.InteropServices;     



private void button1_Click(object sender, System.EventArgs e)
        {
            // Allow the user to select a file.
            OpenFileDialog ofd = new OpenFileDialog();
            if( DialogResult.OK == ofd.ShowDialog(this) )
            {
                // Allow the user to select a printer.
                PrintDialog pd  = new PrintDialog();
                pd.PrinterSettings = new PrinterSettings();
                if( DialogResult.OK == pd.ShowDialog(this) )
                {
                    // Print the file to the printer.
                    RawPrinterHelper.SendFileToPrinter(pd.PrinterSettings.PrinterName, ofd.FileName);
                }
            }

    }

private void button2_Click(object sender, System.EventArgs e)
{
    string s = "Hello"; // device-dependent string, need a FormFeed?

    // Allow the user to select a printer.
    PrintDialog pd  = new PrintDialog();
    pd.PrinterSettings = new PrinterSettings();
    if( DialogResult.OK == pd.ShowDialog(this) )
    {
        // Send a printer-specific to the printer.
        RawPrinterHelper.SendStringToPrinter(pd.PrinterSettings.PrinterName, s);
    }
}

public class RawPrinterHelper
{
    // Structure and API declarions:
    [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Ansi)]
    public class DOCINFOA
    {
        [MarshalAs(UnmanagedType.LPStr)] public string pDocName;
        [MarshalAs(UnmanagedType.LPStr)] public string pOutputFile;
        [MarshalAs(UnmanagedType.LPStr)] public string pDataType;
    }
    [DllImport("winspool.Drv", EntryPoint="OpenPrinterA", SetLastError=true, CharSet=CharSet.Ansi, ExactSpelling=true, CallingConvention=CallingConvention.StdCall)]
    public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, IntPtr pd);

[DllImport("winspool.Drv", EntryPoint="ClosePrinter", SetLastError=true, ExactSpelling=true, CallingConvention=CallingConvention.StdCall)]
public static extern bool ClosePrinter(IntPtr hPrinter);

[DllImport("winspool.Drv", EntryPoint="StartDocPrinterA", SetLastError=true, CharSet=CharSet.Ansi, ExactSpelling=true, CallingConvention=CallingConvention.StdCall)]
public static extern bool StartDocPrinter( IntPtr hPrinter, Int32 level,  [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);

[DllImport("winspool.Drv", EntryPoint="EndDocPrinter", SetLastError=true, ExactSpelling=true, CallingConvention=CallingConvention.StdCall)]
public static extern bool EndDocPrinter(IntPtr hPrinter);

[DllImport("winspool.Drv", EntryPoint="StartPagePrinter", SetLastError=true, ExactSpelling=true, CallingConvention=CallingConvention.StdCall)]
public static extern bool StartPagePrinter(IntPtr hPrinter);

[DllImport("winspool.Drv", EntryPoint="EndPagePrinter", SetLastError=true, ExactSpelling=true, CallingConvention=CallingConvention.StdCall)]
public static extern bool EndPagePrinter(IntPtr hPrinter);

[DllImport("winspool.Drv", EntryPoint="WritePrinter", SetLastError=true, ExactSpelling=true, CallingConvention=CallingConvention.StdCall)]
public static extern bool WritePrinter(IntPtr hPrinter, IntPtr pBytes, Int32 dwCount, out Int32 dwWritten );

// SendBytesToPrinter()
// When the function is given a printer name and an unmanaged array
// of bytes, the function sends those bytes to the print queue.
// Returns true on success, false on failure.
public static bool SendBytesToPrinter( string szPrinterName, IntPtr pBytes, Int32 dwCount)
{
    Int32    dwError = 0, dwWritten = 0;
    IntPtr    hPrinter = new IntPtr(0);
    DOCINFOA    di = new DOCINFOA();
    bool    bSuccess = false; // Assume failure unless you specifically succeed.

    di.pDocName = "My C#.NET RAW Document";
    di.pDataType = "RAW";

    // Open the printer.
    if( OpenPrinter( szPrinterName.Normalize(), out hPrinter, IntPtr.Zero ) )
    {
        // Start a document.
        if( StartDocPrinter(hPrinter, 1, di) )
        {
            // Start a page.
            if( StartPagePrinter(hPrinter) )
            {
                // Write your bytes.
                bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);
                EndPagePrinter(hPrinter);
            }
            EndDocPrinter(hPrinter);
        }
        ClosePrinter(hPrinter);
    }
    // If you did not succeed, GetLastError may give more information
    // about why not.
    if( bSuccess == false )
    {
            dwError = Marshal.GetLastWin32Error();
    }
    return bSuccess;
}

public static bool SendFileToPrinter( string szPrinterName, string szFileName )
{
    // Open the file.
    FileStream fs = new FileStream(szFileName, FileMode.Open);
    // Create a BinaryReader on the file.
    BinaryReader br = new BinaryReader(fs);
    // Dim an array of bytes big enough to hold the file's contents.
    Byte []bytes = new Byte[fs.Length];
    bool bSuccess = false;
    // Your unmanaged pointer.
    IntPtr pUnmanagedBytes = new IntPtr(0);
    int nLength;

    nLength = Convert.ToInt32(fs.Length);
    // Read the contents of the file into the array.
    bytes = br.ReadBytes( nLength );
    // Allocate some unmanaged memory for those bytes.
    pUnmanagedBytes = Marshal.AllocCoTaskMem(nLength);
    // Copy the managed byte array into the unmanaged array.
    Marshal.Copy(bytes, 0, pUnmanagedBytes, nLength);
    // Send the unmanaged bytes to the printer.
    bSuccess = SendBytesToPrinter(szPrinterName, pUnmanagedBytes, nLength);
    // Free the unmanaged memory that you allocated earlier.
    Marshal.FreeCoTaskMem(pUnmanagedBytes);
    return bSuccess;
}
public static bool SendStringToPrinter( string szPrinterName, string szString )
{
    IntPtr pBytes;
    Int32 dwCount;
    // How many characters are in the string?
    dwCount = szString.Length;
    // Assume that the printer is expecting ANSI text, and then convert
    // the string to ANSI text.
    pBytes = Marshal.StringToCoTaskMemAnsi(szString);
    // Send the converted ANSI string to the printer.
    SendBytesToPrinter(szPrinterName, pBytes, dwCount);
    Marshal.FreeCoTaskMem(pBytes);
    return true;
}