如何使用JNA調用GetRawInputDeviceInfo？

Question

我想使用JNA從我的Java應用程序調用GetRawInputDeviceInfo。

這是我JNA Library接口的樣子：

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); 

然後，我用GetRawInputDeviceInfo像這樣：（假設hDevice是從什麼地方得到有效的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); 

我的問題是lResult是-1，GetRawInputDeviceInfo的文檔中指出pData對於設備信息來說不夠大。我是否錯誤地定義了pData或cbSize？如果是這樣，在這種情況下定義它們的正確方法是什麼？

我的JNA版本是4.1.0。我的應用程序在Windows 7 64位上的Java 8上運行。

Answer 1

至少你需要修改你的結構以具有適當的表示。您目前有三個單獨的字段，而您應該有一個Union。這會使你的結構尺寸比預期的大。

另外，您應該直接將結構作爲第三個參數傳遞（使用PointerByReference不僅不正確，而且本機代碼將接收指針的地址而不是結構的地址）。直接傳遞結構時，JNA知道何時需要將Java字段與本機內存同步。

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); 
} 

然後使用它是這樣的：

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);