JAVA calls the dll file program code in windows

Java is a very powerful program. It can do a lot of operations. Next I will introduce the program code for calling windows dll files in java. For your reference, please refer.

JNA (Java Native Access): An open-source Java framework built on JNI. SUN leads the development and is used to call C and C ++ code, especially the underlying library files (dll files in windows and so [shared object] files in linux ).

JNI is the only mechanism for Java to call native functions. JNA is built on JNI. JNA simplifies Java's process of calling native functions. JNA provides a dynamic C language editor (actually a dynamic link library, in the Linux-i386 file name is: libjnidispatch. so) can automatically realize the data type ing between Java and C. The performance is lower than that of the dynamic link library called by JNI technology.

1. Write a windows dll and name the file forjava. dll. One of the add functions adopts the stdcall call convention.

The Code is as follows:

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Main. h file # Ifndef _ MAIN_H __ # Define _ MAIN_H __ # Include <windows. h> /* To use this exported function of dll, include this header * In your project. */ # Ifdef BUILD_DLL # Define DLL_EXPORT _ declspec (dllexport) _ stdcall # Else # Define DLL_EXPORT _ declspec (dllimport) _ stdcall # Endif # Ifdef _ cplusplus Extern "C" { # Endif Int DLL_EXPORT add (int a, int B ); # Ifdef _ cplusplus } # Endif # Endif/_ MAIN_H __ Main. cpp # Include "main. h" // A sample exported function Int DLL_EXPORT add (int a, int B) { Return a + B; } Extern "C" DLL_EXPORT bool apientry DllMain (HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved) { Switch (fdwReason) { Case DLL_PROCESS_ATTACH: // Attach to process // Return FALSE to fail DLL load Break; Case DLL_PROCESS_DETACH: // Detach from process Break; Case DLL_THREAD_ATTACH: // Attach to thread Break; Case DLL_THREAD_DETACH: // Detach from thread Break; } Return TRUE; // succesful }

2. Import jna. jar into the eclipse project. The java code is as follows:

The Code is as follows:

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// Import com. sun. jna. Library; cdecl call Import com. sun. jna. Native; Import com. sun. jna. Platform; Import com. sun. jna. win32.StdCallLibrary; Public class main { Public interface CLibrary extends StdCallLibrary {// Library when cdecl call is called CLibrary INSTANCE = (CLibrary) Native. loadLibrary ("forjava", CLibrary. class ); Public int add (int a, int B ); } Public static void main (String [] args ){ System. out. print (CLibrary. INSTANCE. add (2, 3 )); } }