Create Java VM from MingW GCJ?

Sat Mar 29 09:35:00 GMT 2003

Hi Ranjit / Erik / Everyone,
Is it possible to create a Java VM from a C program on
MingW? The linker is complaining about unresolved symbols
and a two-second explanation from you will save me
hours of banging my head against the wall.
Thanks.
-- Mohan
http://www.thisiscool.com/
http://www.animalsong.org/
build.bat
---------
setlocal
set TOP=D:\temp\thisiscool-gcc\gcc-3.3
set TOP=D:\PROGRA~1\thisiscool-gcc\gcc-3.3
PATH %TOP%\bin;%PATH%
gcj -c -fjni Prog.java -o prog.o
gcc -c -I%TOP%\include invoke.c -o invoke.o
gcj -o prog.exe prog.o invoke.o
endlocal
Built output
------------
invoke.o(.text+0xc4):invoke.c: undefined reference to `_imp__JNI_GetDefaultJavaVMInitArgs@4'
invoke.o(.text+0xdd):invoke.c: undefined reference to `_imp__JNI_CreateJavaVM@12'
invoke.c
--------
#include <jni.h>
#ifdef _WIN32
#define PATH_SEPARATOR ';'
#else /* UNIX */
#define PATH_SEPARATOR ':'
#endif
#define USER_CLASSPATH "." /* where Prog.class is */
main() {
 JNIEnv *env;
 JavaVM *jvm;
 JavaVMInitArgs vm_args;
 jint res;
 jclass cls;
 jmethodID mid;
 jstring jstr;
 jobjectArray args;
 char classpath[1024];
 /* IMPORTANT: specify vm_args version # if you use JDK1.1.2 and beyond */
 vm_args.version = 0x00010002;
 JNI_GetDefaultJavaVMInitArgs(&vm_args);
 /* Create the Java VM */
 res = JNI_CreateJavaVM(&jvm,(void**) &env,&vm_args);
 if (res < 0) {
 fprintf(stderr, "Can't create Java VM\n");
 exit(1);
 }
 cls = (*env)->FindClass(env, "Prog");
 if (cls == 0) {
 fprintf(stderr, "Can't find Prog class\n");
 exit(1);
 }
 mid = (*env)->GetStaticMethodID(env, cls, "main", "([Ljava/lang/String;)V");
 if (mid == 0) {
 fprintf(stderr, "Can't find Prog.main\n");
 exit(1);
 }
 jstr = (*env)->NewStringUTF(env, " from C!");
 if (jstr == 0) {
 fprintf(stderr, "Out of memory\n");
 exit(1);
 }
 args = (*env)->NewObjectArray(env, 1,
 (*env)->FindClass(env, "java/lang/String"), jstr);
 if (args == 0) {
 fprintf(stderr, "Out of memory\n");
 exit(1);
 }
 (*env)->CallStaticVoidMethod(env, cls, mid, args);
 (*jvm)->DestroyJavaVM(jvm);
}
Prog.java
---------
public class Prog {
 public static void main(String[] args) {
 System.out.println("Hello World" + args[0]);
 System.out.println("gnu.gcj.progname = "+System.getProperty("gnu.gcj.progname"));
 }
}