C#通过LPT控制打印机——txt文档读取指令打印条码

//C#控制打印机(直接发送打印机命令到打印机)
//一个打印机控制类,很有用的,其中使用了windows api控制lpt端口,对条码打印机的控制方法如下:将打印机的命令写到一个文件里，再使用之。
//该实例从txt文档读取指令然后写入到LPT1端口
//代码：
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
 
namespace LPTControls
{
    public class LPTControls
    {
        [StructLayout(LayoutKind.Sequential)]
        private struct OVERLAPPED
        {
            int Internal;
            int InternalHigh;
            int Offset;
            int OffSetHigh;
            int hEvent;
        }
        [DllImport("kernel32.dll")]
        private static extern int CreateFile(string lpFileName, 
            uint dwDesiredAccess, 
            int dwShareMode, 
            int lpSecurityAttributes, 
            int dwCreationDisposition, 
            int dwFlagsAndAttributes, 
            int hTemplateFile);
        [DllImport("kernel32.dll")]
        private static extern bool WriteFile(int hFile,
            byte[] lpBuffer, 
            int nNumberOfBytesToWriter, 
            out int lpNumberOfBytesWriten, 
            out OVERLAPPED lpOverLapped);
        [DllImport("kernel32.dll")]
        private static extern bool CloseHandle(int hObject);

        private int iHandle;
        //打开LPT 端口
        public bool Open()
        {
            iHandle = CreateFile("lpt1", 0x40000000, 0, 0, 3, 0, 0);
            if (iHandle != -1)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        //打印函数，参数为打印机的命令或者其他文本！
        public bool Write(string MyString)
        {
            if (iHandle != 1)
            {
                int i;
                OVERLAPPED x;
                byte[] mybyte = System.Text.Encoding.Default.GetBytes(MyString);
                return WriteFile(iHandle, mybyte, mybyte.Length, out i, out x);
            }
            else
            {
                throw new Exception("端口未打开~！");
            }
        }
        //关闭打印端口
        public bool Close()
        {
            return CloseHandle(iHandle);
        }
    }
}

 //使用方法
private void button1_Click(object sender, EventArgs e)
{
    LPTControls.LPTControls lpt = new LPTControls.LPTControls();
    string mycommanglines = System.IO.File.ReadAllText("print.txt");//print.txt里写了条码机的命令
    lpt.Open();
    lpt.Write(mycommanglines);
    lpt.Close();
}