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目前我有 2 台计算机尝试连接并打印到单个网络打印机。问题在于ptr.open("POSPrinter_LAN_1");无法首先连接的打印机总是会抛出此异常的方法：

jpos.JposException: Can not open the communication port.
at com.sewoo.jpos.POSPrinterService.open(POSPrinterService.java:729)
at jpos.BaseJposControl.open(BaseJposControl.java:371)
at ReceiptTestSingleNetworkPrinter.main(ReceiptTestSingleNetworkPrinter.java:31)

因此有没有办法让打印机等待连接再次被释放/释放？

我目前的代码：

import jpos.*;
import jpos.JposConst;
import jpos.JposException;
import jpos.POSPrinter;
import jpos.POSPrinterConst;

import jpos.util.JposPropertiesConst;

public class ReceiptTestSingleNetworkPrinter
{
    public static void main(String[] args)
    {   
       // constants defined for convience sake (could be inlined)
        String ESC    = ((char) 0x1b) + "";
        String LF     = ((char) 0x0a) + "";
        String SPACES = "                                                                      ";


        POSPrinter ptr = new POSPrinter();     

        try
        {
        // To test Printer          
        ptr.open("POSPrinter_LAN_1");
        ptr.claim(100000);
        ptr.setDeviceEnabled(true);

        // begining a transaction
        // This transaction mode causes all output to be buffered
        ptr.transactionPrint(POSPrinterConst.PTR_S_RECEIPT, POSPrinterConst.PTR_TP_TRANSACTION);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|cA" + ESC + "|4C" + ESC + "|bC" + "Receipt" + LF + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|rA" + ESC + "|bC" + "TEL (123)-456-7890" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|cA" + ESC + "|bC" + "Thank you for coming to our shop!" + LF + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, "Chicken                             $10.00" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, "Hamburger                           $20.00" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, "Pizza                               $30.00" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, "Lemons                              $40.00" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, "Drink                               $50.00" + LF + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, "Excluded tax                       $150.00" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|uC" + "Tax(5%)                              $7.50" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|bC" + ESC + "|2C" + "Total         $157.50" + LF + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|bC" + "Payment                            $200.00" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|bC" + "Change                              $42.50" + LF);
        ptr.printNormal(POSPrinterConst.PTR_S_RECEIPT, ESC + "|100fP");
        // terminate the transaction causing all of the above buffered data to be sent to the printer
        ptr.transactionPrint(POSPrinterConst.PTR_S_RECEIPT, POSPrinterConst.PTR_TP_NORMAL);

        // release current printer
        ptr.setDeviceEnabled(false);
        ptr.release();
        ptr.close();
    }
    catch(JposException e)
    {
        e.printStackTrace();
    }
    finally
    {

        System.exit(0);
    }
    }
}
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1 回答 1

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作为一种可能性，即使由于某种原因关闭执行后，第一台计算机和打印机之间的连接也没有断开。

但是，根据 JavaPOS 的规范，它可以从任意数量的计算机上打开。只有Claim成功的计算机才能在Claim之后正常调用，直到Release。

因此，您的打印机的硬件和 JavaPOS 控制可能不符合 JavaPOS 规范。

通过网络连接的设备的共享/独占控制很困难，因此可能无法实现。

向您的打印机供应商询问该问题以及如何使用它。

于 2018-08-07T10:52:44.337 回答