无法从Java类调用静态库函数

Question

Say I have a static C++ lib, DataPacker.lib and is linked to a shared dynamic link library called Command.dll.

The static library exposes following function,

//Datapacker.h
#ifdef __cplusplus
extern "C" {
#endif
JNIEXPORT void JNICALL Java__Observer_sendToClient
(JNIEnv *, jclass, jobject);
#ifdef __cplusplus
}
#endif

//Datapacker.cpp
JNIEXPORT void JNICALL Java__Observer_sendToClient
(JNIEnv *, jclass, jobject)
{
//Print
}

Now I tried to call above function from java class as follows,

//Observer.Java
class Observer
{
static{
System.loadLibrary("Command");
}
public static void main(String[] args) {
try{
sendToClient();
} 
catch (Throwable t){
System.err.println("Native code library failed to load.\n" +  t.getMessage());
}
}
private static native void sendToClient();
}

But am getting following exception from java,

"Native code library failed to load.Observer.sendToClient()V"

The call works fine when it is moved from DataPacker.lib to command.lib. Please help.

Answer 1

c++ linker didnt add DataPacker.lib code into Command.dll. if you want to call function you must write proxy function in the Command.dll for DataPacker.lib(global export function for java calls) for example dll code: #include #ifdef _ cplusplus extern "C" { #endif JNIEXPORT void JNICALL Java _Observer_sendToClient (JNIEnv *, jclass, jobject); #ifdef __cplusplus } #endif

    //DatapackerDLL.cpp
    JNIEXPORT void JNICALL Java__Observer_sendToClient
    (JNIEnv *, jclass, jobject)
    {
     DataPacker::sendToClient();
    }