[英]How to use JNA callback
I am using JNA to call functions of a dll file. 我正在使用JNA来调用dll文件的函数。
simpleDLL.h: simpleDLL.h:
typedef int (__stdcall *eventCallback)(unsigned int id, int value);
namespace test
{
class hotas
{
public:
static __declspec(dllexport) int readValue(int a);
static __declspec(dllexport) void setCallback(eventCallback evnHnd);
};
}
simpleDLL.cpp: simpleDLL.cpp:
#include "simpleDLL.h"
#include <stdexcept>
using namespace std;
namespace test
{
eventCallback callback1 = NULL;
int test::readValue(int a)
{
return 2*a;
}
void test::setCallback(eventCallback evnHnd)
{
callback1 = evnHnd;
}
}
My Java Interface looks like this: 我的Java接口如下所示:
public interface DLLMapping extends Library{
DLLMapping INSTANCE = (DLLMapping) Native.loadLibrary("simpleDLL", DLLMapping.class);
int readValue(int a);
public interface eventCallback extends Callback {
boolean callback(int id, int value);
}
public void setCallback(eventCallback evnHnd);
}
And finally the java main: 最后java主:
public static void main(String[] args) {
DLLMapping sdll = DLLMapping.INSTANCE;
int a = 3;
int result = sdll.readValue(a);
System.out.println("Result: " + result);
sdll.setCallback(new eventCallback(){
public boolean callback(int id, int value) {
//System.out.println("bla");
return true;
}
});
}
My problem is that I got the error, that java cannot find the function setCallback. 我的问题是我得到了错误,java无法找到函数setCallback。 What's wrong on my code?
我的代码出了什么问题?
Thank you for your help! 谢谢您的帮助!
C++ is not the same thing as C. Dump the symbols from your DLL (http://dependencywalker.com), and you will see that the function name (at least from the linker's point of view) is not "setCallback". C ++与C不同。转储DLL中的符号(http://dependencywalker.com),您将看到函数名称(至少从链接器的角度来看)不是“setCallback”。
Use extern "C"
to avoid name mangling on exported functions, rename your Java function to match the exported linker symbol, or use a FunctionMapper to map the Java method name to the linker symbol. 使用
extern "C"
可以避免在导出的函数上进行名称修改,重命名Java函数以匹配导出的链接器符号,或使用FunctionMapper将Java方法名称映射到链接器符号。
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