如何使用 JNA 将包含结构数组的结构传递给 C++ 函数? [英] How do I pass a Structure that contains an array of Structures to a C++ function using JNA?
问题描述
我正在构建一个 Java 应用程序，该应用程序使用 JNA 与特定制造商的 API 进行通信.我已经映射了大量函数调用并且已经在运行，但是有一对函数让我感到有些难过.
I am building a Java application that communicates with a particular manufacturer's API using JNA. I have a ton of function calls mapped and already working, but there are a pair of functions that have been giving me some grief.
这两个函数来回传递数据结构来配置设备.该结构中有一个嵌套的数据结构数组.
Both of these functions pass a data structure back and forth to configure the device. This structure has a nested array of data structures within it.
原生定义:
VISION_API_DECL BOOL VISION_API SetDeviceParameters( DWORD DeviceID, DeviceParameters DeviceParam );
VISION_API_DECL BOOL VISION_API GetDeviceParameters( DWORD DeviceID, DeviceParameters *DeviceParam );
我在 Java 中像这样声明了它们:
I have them declared in Java like so:
public interface Driver extends Library {
...
public boolean SetDeviceParameters(int DeviceID, DEVICE_PARAMETERS DeviceParam);
public boolean GetDeviceParameters(int DeviceID, DEVICE_PARAMETERS DeviceParam);
...
}
这些函数调用似乎起作用了.当我调用这两个函数中的任何一个时，JNA 都不会抛出异常.当我调用 GetDeviceParameters 方法并打印出结构体时，我看到其中大部分填充了我认为是设备默认配置的数据.但是，当我使用刚从 get 调用返回的相同数据调用 SetDeviceParameters 方法时，设备返回一个错误，指出参数错误.
These function calls seem to work. JNA does not throw an exception when I call either of those functions. When I call the GetDeviceParameters method and print out the struct, I see most of it filled with data from what I would assume is the device's default configuration. However, when I call the SetDeviceParameters method using the same data just returned from the get call, the device returns an error saying the parameters are wrong.
我如何知道我是否正确映射了结构?
本地:
typedef struct _DeviceParameters
{
BOOL bMICREnable;
UINT nMICRFont;
BOOL bMICRSaveSamples;
UINT nMICRSpaces;
char cRejectSymbol;
UINT nReserved;
BOOL bReserved;
IMAGE_PROPERTIES ImagePropertiesFront1;
IMAGE_PROPERTIES ImagePropertiesFront2;
IMAGE_PROPERTIES ImagePropertiesRear1;
IMAGE_PROPERTIES ImagePropertiesRear2;
SNIPPET_PROPERTIES SnippetProperties[10];
BOOL bPrintEnable;
BOOL bOneDoc;
UINT nFeedingMode;
} DeviceParameters;
typedef struct _SnippetProperties
{
BOOL Enable;
BOOL Front;
Snippet Properties;
} SNIPPET_PROPERTIES;
typedef struct _Snippet
{
UINT Xposition;
UINT Yposition;
UINT Width;
UINT Height;
UINT Orientation;
UINT Color;
UINT Compression;
BOOL Millimeters;
} Snippet;
typedef struct _ImageProperties
{
UINT Format;
UINT Paging;
UINT Resolution;
UINT ColorDepth;
UINT Threshold;
} IMAGE_PROPERTIES;
Java:
public class DEVICE_PARAMETERS extends Structure {
public boolean bMICREnable;
public int nMICRFont;
public boolean bMICRSaveSamples;
public int nMICRSpaces;
public byte cRejectSymbol;
public int nReserved;
public boolean bReserved;
public IMAGE_PROPERTIES ImagePropertiesFront1;
public IMAGE_PROPERTIES ImagePropertiesFront2;
public IMAGE_PROPERTIES ImagePropertiesRear1;
public IMAGE_PROPERTIES ImagePropertiesRear2;
public SNIPPET_PROPERTIES[] SnippetProperties = new SNIPPET_PROPERTIES[10];
public boolean bPrintEnable;
public boolean bOneDoc;
public int nFeedingMode;
@Override
protected List getFieldOrder() {
return Arrays.asList(
"bMICREnable"
, "nMICRFont"
, "bMICRSaveSamples"
, "nMICRSpaces"
, "cRejectSymbol"
, "nReserved"
, "bReserved"
, "ImagePropertiesFront1"
, "ImagePropertiesFront2"
, "ImagePropertiesRear1"
, "ImagePropertiesRear2"
, "SnippetProperties"
, "bPrintEnable"
, "bOneDoc"
, "nFeedingMode"
);
}
}
public class IMAGE_PROPERTIES extends Structure {
public int Format;
public int Paging;
public int Resolution;
public int ColorDepth;
public int Threshold;
@SuppressWarnings("RedundantArrayCreation")
@Override
protected List getFieldOrder() {
return Arrays.asList(
new String[]{
"Format"
, "Paging"
, "Resolution"
, "ColorDepth"
, "Threshold"
}
);
}
}
public class SNIPPET_PROPERTIES extends Structure {
public boolean Enable;
public boolean Front;
public SNIPPET Properties = new SNIPPET();
@Override
protected List getFieldOrder() {
return Arrays.asList("Enable", "Front", "Properties");
}
}
public class SNIPPET extends Structure {
public int Xposition;
public int Yposition;
public int Width;
public int Height;
public int Orientation;
public int Color;
public int Compression;
public boolean Millimeters;
@Override
protected List getFieldOrder() {
return Arrays.asList("Xposition"
, "Yposition"
, "Width"
, "Height"
, "Orientation"
, "Color"
, "Compression"
, "Millimeters"
);
}
}
输出:
DEVICE_PARAMETERS(auto-allocated@0x16a25938 (520 bytes)) {
boolean bMICREnable@0=false
int nMICRFont@4=1
boolean bMICRSaveSamples@8=false
int nMICRSpaces@c=2
byte cRejectSymbol@10=3f
int nReserved@14=0
boolean bReserved@18=false
IMAGE_PROPERTIES ImagePropertiesFront1@1c=IMAGE_PROPERTIES(allocated@0x16a25954 (20 bytes) (shared from auto-allocated@0x16a25938 (520 bytes))) {
int Format@0=0
int Paging@4=0
int Resolution@8=0
int ColorDepth@c=0
int Threshold@10=0
}
IMAGE_PROPERTIES ImagePropertiesFront2@30=IMAGE_PROPERTIES(allocated@0x16a25968 (20 bytes) (shared from auto-allocated@0x16a25938 (520 bytes))) {
int Format@0=0
int Paging@4=0
int Resolution@8=0
int ColorDepth@c=0
int Threshold@10=0
}
IMAGE_PROPERTIES ImagePropertiesRear1@44=IMAGE_PROPERTIES(allocated@0x16a2597c (20 bytes) (shared from auto-allocated@0x16a25938 (520 bytes))) {
int Format@0=0
int Paging@4=0
int Resolution@8=0
int ColorDepth@c=0
int Threshold@10=0
}
IMAGE_PROPERTIES ImagePropertiesRear2@58=IMAGE_PROPERTIES(allocated@0x16a25990 (20 bytes) (shared from auto-allocated@0x16a25938 (520 bytes))) {
int Format@0=0
int Paging@4=0
int Resolution@8=0
int ColorDepth@c=0
int Threshold@10=0
}
SNIPPET_PROPERTIES SnippetProperties[10]@6c=[Lpanini.data.SNIPPET_PROPERTIES;@fb642f
boolean bPrintEnable@1fc=false
boolean bOneDoc@200=false
int nFeedingMode@204=1
}
memory dump
[00000000]
[01000000]
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[02000000]
[3f000000]
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[01000000]
Device Error: Wrong device parameters <-- this is where I try to set params
推荐答案
你没有包含你的方法声明，它应该是这样的(假设你没有简单地在声明中打错字):
You haven't included your method declarations, which should look like this (assuming you haven't simply made a typo in the declaration):
boolean SetDeviceParameters(int deviceID, DeviceParameters.ByValue params);
boolean GetDeviceParameters(int deviceID, DeviceParameters params);
确保在传递给 SetDeviceParameters() 方法时使用标记有 Structure.ByValue 的结构版本.您需要定义结构的 ByValue 版本.
Make sure that you use a version of the structure tagged with Structure.ByValue when passing to the SetDeviceParameters() method. You'll need to define a ByValue version of your structure.
public class DeviceParameters extends Structure {
public ByValue extends DeviceParameters implements Structure.ByValue {
public ByValue() { }
public ByValue(Pointer p) { super(p); read(); }
}
}
然后您可以像这样从 struct * 转换为 struct:
You can then convert from struct * to struct like this:
DeviceParameters dp = new DeviceParameters();
DeviceParameters.ByValue bv = new DeviceParameters.ByValue(dp.getPointer());
这篇关于如何使用 JNA 将包含结构数组的结构传递给 C++ 函数?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
