c# 调用ＤＬＬ（开发小票打印机）

最近买了一台芯烨　的８０宽度网络小票打印机，计划做一个类似后厨的实时接单打印程序，即每接到一个订单，系统就自动打印小票，驱动配货人员尽快工作。

厂家提供了ＤＬＬ文件，一切从０开始摸索。

首先是要引入ＤＬＬ，使用DllImport，指定引用的ＤＬＬ名称，方式，编码格式等　；

[DllImport("user32.dll", EntryPoint = "MessageBoxA")]
        static extern int MsgBox(int hWnd, string msg, string caption, int type);

        [DllImport("JsPrinterDll.dll", EntryPoint = "uniInitNetSev",CharSet =CharSet.Ansi,CallingConvention =CallingConvention.StdCall)]
        static extern bool  uniInitNetSev();

        [DllImport("JsPrinterDll.dll", EntryPoint = "uniConnectNetPortByIp", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
        static extern int uniConnectNetPortByIp(string ip, int port = 9100, int Timeout = 5000);
        [DllImport("JsPrinterDll.dll", EntryPoint = "uniPrintImg1b2a", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
        static extern int uniPrintImg1b2a(int fs,string imgpath);

        private void button1_Click(object sender, EventArgs e)
        {

            bool openPrint = uniInitNetSev();
            if (!openPrint) 
            { 
                MessageBox.Show("打印机初始化失败");
                return;
            }

            int printState = uniConnectNetPortByIp("100.１.１.219", 9100, 5000);
            if (printState <= 0) return;


            int nret = uniPrintImg1b2a(printState,"test.bmp");
            if (nret <= 0)
            {
                return;
            }
            MessageBox.Show("测试打印OK", nret.ToString());
        }