Compile the DLL using GCC and call the DLL using Java.

We use examples to learn how to compile DLL files using gcc. The following example shows the process. There are three files in total: Hello. c. dll. H and DLL. c. hello. the content of the C file is as follows # include <stdio. h> # include/"DLL. h/"int main ()

{Hello (); Return 0;} among them, the hello () function is a function provided by the dynamic Connection Library. The DLL. h file content is as follows # ifdef build_dll/* DLL Export */# define export _ declspec (dllexport) # Else/* EXE import */# define export _ declspec (dllimport) # Endif export void Hello (void ); The DLL. c file content is as follows # include/"DLL. h/" Export void Hello (void) {Printf (/"Hello // n /");}

The content of the three files is very simple and does not need to be explained.

Compile the Connection Program

1. Compile hello. c gcc-C hello. C.

2. Compile DLL. c gcc-C-dbuild_dll. C. Use-dbuild_dll to set the macro build_dll.

3. Create a DLL gcc-shared-O message. DLL. o-wl, -- Out-implib, libmessage. a. The shared parameter is used to create a shared library. In Windows, DLL-WL is used to wait for the next information to connect. The out-implib parameter is used by the Connection Program lD, used to create the import library required to connect to the DLL.

4. Create the executable file gcc-O hello.exe hello. o-l. /-lmessage-L specifies the connection library path-lmessage (or-l message) specifies the DLL import library. The compilation connection is complete and the program C: //> hello!

 

 

 

 

 

 

 

The following is an example of calling a DLL using Java.

 

Recently I used Java to Call DLL and found the jnative open source on the Internet.
How to use it?
Write a DLL experiment by yourself.
Therefore, the C/C ++ compiler is recommended for mingw.
Write a head file first:
Test. h:

 

C code

1. # Ifndef mingw_dll_h __
2. # Define mingw_dll_h __
3. IntAdd (IntA,IntB );
4. # Endif

#ifndef MINGW_DLL_H__#define MINGW_DLL_H__int add(int a,int b);#endif

 

 

Then write the c file:
Test. C:

C code

1. # Include <stdio. h>
2. # Include "test. H"
3. IntAdd (IntA,IntB ){
4. Printf ("/N ");
5. Printf ("DLL function add () called/N ");
6. ReturnA + B;
7. }

#include <stdio.h>#include "test.h"int add(int a,int b){  printf("/n");  printf("dll function add() called/n");  return a+b;}

 

 

Use mingw to compile C into a DLL. The command is as follows:

C code

1. Gcc-wall-shared test. C-O test. dll

gcc -Wall -shared test.c -o test.dll

 

 

Put test. dll under system32,
Finally, it is time to write our Java code:
Test. Java:

Java code

1. ImportOrg. xvolks. jnative. jnative;
2. ImportOrg. xvolks. jnative. type;
3. ImportOrg. xvolks. jnative. Exceptions. nativeexception;
5. Public ClassTest {
6. Public StaticIntTestjnative (IntA,IntB)ThrowsNativeexception, illegalaccessexception {
7. Jnative n =Null;
8. Try{
9. N =NewJnative ("Zzz. dll", "add ");
10. N. setretval (type. INT );
11. N. setparameter (0, );
12. N. setparameter (1, B );
13. N. Invoke ();
14. System. Out. println ("Return:" + N. getretval ());
15. ReturnInteger. parseint (N. getretval ());
16. }Finally{
17. If(N! =Null)
18. N. Dispose ();
19. }
20. }
21. Public Static VoidMain (string [] ARGs)ThrowsNativeexception, illegalaccessexception {
22. Testjnative (1, 4 );
23. }
24. }

Import Org. xvolks. jnative. jnative; import Org. xvolks. jnative. type; import Org. xvolks. jnative. exceptions. nativeexception; public class test {public static int testjnative (int A, int B) throws nativeexception, illegalaccessexception {jnative n = NULL; try {n = new jnative ("Zzz. DLL "," add "); N. setretval (type. INT); N. setparameter (0, a); N. setparameter (1, B); N. invoke (); system. out. println ("Return:" + N. get Retval (); Return integer. parseint (N. getretval ();} finally {If (n! = NULL) n. Dispose () ;}} public static void main (string [] ARGs) throws nativeexception, illegalaccessexception {testjnative (1, 4 );}}

 

 

OK!
Run the following command to try it. The result is as follows:
Return Value: 5.
DLL function add () called

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>--------------- >>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>

This is not troublesome, but mingw is difficult, but after all, it has been done. The following is my method:
First to the http://sourceforge.net/project/showfiles.php? Group_id = 2435
Find the first one: Automated mingw installer, download it, and install it. During installation, select all installation options,
It automatically downloads all required files.
At the beginning, I downloaded files one by one according to the method described on the Internet. If I didn't pay attention to this, I always reported fewer files,
Later, I found out that he deleted all the original ones. OK!

Jnative is: http://sourceforge.net/project/showfiles.php? Group_id = 156421, This is not difficult,
Put the DLL it carries under system32 and it will be OK!