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我们正在尝试实现一个.NET服务对象，该对象支持COM接口来模拟POSPrinter，但仍旧与旧技术兼容。使用.NET POS SDK连接C++ POS控件的问题
我们有我们的接口，并在下面的类类对象..
using [...]
namespace yRPOSPrinterDotNet
{
[Guid("2D570F11-4BD8-40e7-BF14-38772063AAF0")]
[InterfaceType(ComInterfaceType.InterfaceIsDual)]
public interface yRPosPrinterCOM
{
long Open(String DeviceName);
long PrintNormal(long Station, String Data);
}
[Guid("478176F4-5105-435c-8EBC-D4CB90B7B1C7")]
[ClassInterface(ClassInterfaceType.None)]
//[ProgId("yRPOSPrinterDotNet.POSPrinter")] //will be set automatically as the progid <namespace><clsid>
public class POSPrinter : yRPosPrinterCOM
{
#region yRPosPrinterCOM Members
public long Open()
{
return 0;
}
public long Open(String DeviceName)
{
Trace.Listeners.Add(new TextWriterTraceListener(Console.Out));
FileStream objStream = new FileStream("C:\\yRPOSLog.txt", FileMode.OpenOrCreate);
TextWriterTraceListener objTraceListener = new TextWriterTraceListener(objStream);
Trace.Listeners.Add(objTraceListener);
Trace.AutoFlush = true;
Trace.Indent();
Trace.WriteLine("Entering Main");
Debug.WriteLine("How does this one do??");
Console.WriteLine("Hello World.");
Trace.WriteLine("Exiting Main");
Trace.Unindent();
return 0;
}
public long PrintNormal(long Station, string Data)
{
throw new NotImplementedException();
}
#endregion
}
}
而且把里面HKEY_LOCAL_MACHINE\SOFTWARE\OLEforRetail\ServiceOPOS\POSPrinter\yReceipts我们yRPosPrinterDotNet.POSPrinter
HKEY_CLASSES_ROOT\CLSID\{478176F4-5105-435C-8EBC-D4CB90B7B1C7}建成后具有正确的ProgID我们（yRPosPrinterDotNet.POSPrinter）
我们可以通过一个测试类来调用DLL（查找ProgID）使用这个类
using [...]
namespace TestYRPosPrinterDotNet
{
/// <summary>
/// Summary description for UnitTest1
/// </summary>
[TestClass]
public class UnitTest1
{
public UnitTest1()
{
}
private TestContext testContextInstance;
/// <summary>
///Gets or sets the test context which provides
///information about and functionality for the current test run.
///</summary>
public TestContext TestContext
{
get
{
return testContextInstance;
}
set
{
testContextInstance = value;
}
}
[TestMethod]
public void TestMethod1()
{
String sProgID = "yRPosPrinterDotNet.POSPrinter";
// We get the type using just the ProgID
Type oType = Type.GetTypeFromProgID(sProgID);
if (oType != null)
{
POSPrinter pp = (POSPrinter)Activator.CreateInstance(oType);
long retVal = pp.Open("Nothing");
}
}
}
}
但是，当我们试图通过样品TestApp调用（它显示为一个serviceObject）
{"Method Open threw an exception. The service object does not support one or more of the methods required by its release."} System.Exception {Microsoft.PointOfService.PosControlException}
通过样品C++控制对象我们收到opos.h限定的104 (const LONG OPOS_E_NOSERVICE = 4 + OPOSERR;)和以下堆栈跟踪
----------------------------------- Doesn't work --------------------------------------------------------
POSPrinterExample.exe!COleDispatchDriver::InvokeHelperV(long dwDispID=37, unsigned short wFlags=1, unsigned short vtRet=3, void * pvRet=0x0012f1e0, const unsigned char * pbParamInfo=0x00702014, char * argList=0x0012f110) Line
397 C++
POSPrinterExample.exe!COleControlSite::InvokeHelperV(long dwDispID=37, unsigned short wFlags=1, unsigned short vtRet=3, void * pvRet=0x0012f1e0, const unsigned char * pbParamInfo=0x00702014, char * argList=0x0012f10c) Line 1093
C++
POSPrinterExample.exe!CWnd::InvokeHelper(long dwDispID=37, unsigned short wFlags=1, unsigned short vtRet=3, void * pvRet=0x0012f1e0, const unsigned char * pbParamInfo=0x00702014, ...) Line 382 C++
POSPrinterExample.exe!COPOSPOSPrinter::Open(const char * DeviceName=0x00271f00) Line 192 + 0x1c bytes C++