如何使用JNA调用GetRawInputDeviceInfo？

Question

我想使用JNA从我的Java应用程序调用GetRawInputDeviceInfo。

这是我JNA Library接口的样子：

public static final UINT RIDI_DEVICEINFO = new UINT(0x2000000b); 

public static DWORD RIM_TYPE_KEYBOARD = new DWORD(1); 

public static class RID_DEVICE_INFO extends Structure { 
    public DWORD cbSize; 
    public DWORD dwType; 
    public RID_DEVICE_INFO_ ridDeviceInfo_; 

    @Override 
    protected List<String> getFieldOrder() { 
    return asList("cbSize", "dwType", "ridDeviceInfo_"); 
    } 
} 

public static class RID_DEVICE_INFO_ extends Structure { 
    public RID_DEVICE_INFO_MOUSE mouse; 
    public RID_DEVICE_INFO_KEYBOARD keyboard; 
    public RID_DEVICE_INFO_HID hid; 

    @Override 
    protected List<String> getFieldOrder() { 
    return asList("mouse", "keyboard", "hid"); 
    } 
} 

public static class RID_DEVICE_INFO_MOUSE extends Structure { 
    public DWORD dwId; 
    public DWORD dwNumberOfButtons; 
    public DWORD dwSampleRate; 
    public BOOL fHasHorizontalWheel; 

    @Override 
    protected List<String> getFieldOrder() { 
    return asList("dwId", "dwNumberOfButtons", "dwSampleRate", "fHasHorizontalWheel"); 
    } 
} 

public static class RID_DEVICE_INFO_KEYBOARD extends Structure { 
    public DWORD dwType; 
    public DWORD dwSubType; 
    public DWORD dwKeyboardMode; 
    public DWORD dwNumberOfFunctionKeys; 
    public DWORD dwNumberOfIndicators; 
    public DWORD dwNumberOfKeysTotal; 

    @Override 
    protected List<String> getFieldOrder() { 
    return asList("dwType", "dwSubType", "dwKeyboardMode", "dwNumberOfFunctionKeys", "dwNumberOfIndicators", "dwNumberOfKeysTotal"); 
    } 
} 

public static class RID_DEVICE_INFO_HID extends Structure { 
    public DWORD dwVendorId; 
    public DWORD dwProductId; 
    public DWORD dwVersionNumber; 
    public USHORT usUsagePage; 
    public USHORT usUsage; 

    @Override 
    protected List<String> getFieldOrder() { 
    return asList("dwVendorId", "dwProductId", "dwVersionNumber", "usUsagePage", "usUsage"); 
    } 
} 

public UINT GetRawInputDeviceInfo(HANDLE hDevice, UINT uiCommand, PointerByReference pData, IntByReference pcbSize); 

然后，我用GetRawInputDeviceInfo像这样：（假设hDevice是从什么地方得到有效的HANDLE）

UINT uiCommand = RIDI_DEVICEINFO; 
RID_DEVICE_INFO deviceInfo = new RID_DEVICE_INFO(); 
deviceInfo.cbSize.setValue(deviceInfo.size()); 
PointerByReference pData = new PointerByReference(deviceInfo.getPointer()); 
IntByReference pcbSize = new IntByReference(deviceInfo.size()); 
UINT lResult = INSTANCE.GetRawInputDeviceInfo(hDevice, uiCommand, pData, pcbSize); 

我的问题是lResult是-1，GetRawInputDeviceInfo的文档中指出pData对于设备信息来说不够大。我是否错误地定义了pData或cbSize？如果是这样，在这种情况下定义它们的正确方法是什么？

我的JNA版本是4.1.0。我的应用程序在Windows 7 64位上的Java 8上运行。

Answer 1

至少你需要修改你的结构以具有适当的表示。您目前有三个单独的字段，而您应该有一个Union。这会使你的结构尺寸比预期的大。

另外，您应该直接将结构作为第三个参数传递（使用PointerByReference不仅不正确，而且本机代码将接收指针的地址而不是结构的地址）。直接传递结构时，JNA知道何时需要将Java字段与本机内存同步。

public interface DeviceAccess extends StdCallLibrary { 
    public static class RID_DEVICE_INFO extends Structure { 
     public int cbSize; 
     public int dwType; 
     public RID_DEVICE_INFO_ ridDeviceInfo_; 

     // Ensure the active field corresponds to what is read back from native memory 
     protected void read() { 
      super.read(); 
      type = RID_DEVICE_INFO_HID.class; 
      switch(dwType) { 
      case RID_DEVICE_INFO_MOUSE: 
       type = RID_DEVICE_INFO_MOUSE.class; break; 
      case RID_DEVICE_INFO_KEYBOARD: 
       type = RID_DEVICE_INFO_KEYBOARD.class; break; 
      default: 
       break; 
      } 
      ridDeviceInfo_.setType(type); 
     } 

     @Override 
     protected List<String> getFieldOrder() { 
      return asList("cbSize", "dwType", "ridDeviceInfo_"); 
     } 
    } 

    public static class RID_DEVICE_INFO_ extends Union { 
     public RID_DEVICE_INFO_MOUSE mouse; 
     public RID_DEVICE_INFO_KEYBOARD keyboard; 
     public RID_DEVICE_INFO_HID hid; 
    } 

    public UINT GetRawInputDeviceInfo(HANDLE hDevice, UINT uiCommand, RID_DEVICE_INFO pData, IntByReference pcbSize); 
} 

然后使用它是这样的：

UINT uiCommand = RIDI_DEVICEINFO; 
RID_DEVICE_INFO deviceInfo = new RID_DEVICE_INFO(); 
// Could also just put this in the constructor 
deviceInfo.cbSize = deviceInfo.size(); 

IntByReference pcbSize = new IntByReference(deviceInfo.size()); 
UINT lResult = INSTANCE.GetRawInputDeviceInfo(hDevice, uiCommand, deviceInfo, pcbSize);