问题描述
我是JNI的新手,我一直在尝试编写一个简单的程序来从C ++调用Java代码.
我在从C创建JavaVM时遇到问题,并且收到链接器错误.我已经尝试过在dev C ++中更改GNU库文件(我正在使用Dev c ++编译器),但到目前为止还没有运气.
JDK版本是1.6.27.
任何人都可以帮助我指出错误或建议逐步方法来编写此程序吗?
这是我要编译的C代码文件.
Hi,
I am new to JNI and I have been trying to write a simple program to call Java code from C++.
I am facing problem in creating the JavaVM from C and am getting the Linker error. I have tried changing the GNU library files in dev C++ (I am using Dev c++ compiler) but no luck so far.
The JDK version is 1.6.27.
Can anybody help me and point out the error or recommend a step-by-step approach to write this program?
Here is the C code file I am trying to compile.
#include <jni.h>
#include <windows.h>
#define PATH_SEPARATOR ';' /* define it to be ':' on Solaris */
#define USER_CLASSPATH "." /* where Prog.class is */
main() {
JNIEnv *env;
JavaVM *jvm;
jint res;
jclass cls;
jmethodID mid;
jstring jstr;
jclass stringClass;
jobjectArray args;
#ifdef JNI_VERSION_1_2
JavaVMInitArgs vm_args;
JavaVMOption options[1];
options[0].optionString =
"-Djava.class.path=" USER_CLASSPATH;
vm_args.version = 0x00010002;
vm_args.options = options;
vm_args.nOptions = 1;
vm_args.ignoreUnrecognized = JNI_TRUE;
/* Create the Java VM */
// this should contain the path to the JVM DLL file
HINSTANCE hVM = LoadLibrary("C:\\Program Files\\Java\\jdk1.6.0_27\\jre6\\bin\\client\\jvm.dll");
if (hVM == NULL)
{
DWORD dwe = GetLastError();
return -1;
}
typedef jint
(CALLBACK *fpCJV)(JavaVM**, void**, JavaVMInitArgs*);
fpCJV CreateJavaVM = (fpCJV)::GetProcAddress(hVM, "JNI_CreateJavaVM");
res = CreateJavaVM(&jvm, (void**)&env, &vm_args);
#else
JDK1_1InitArgs vm_args;
char classpath[1024];
vm_args.version = 0x00010001;
JNI_GetDefaultJavaVMInitArgs(&vm_args);
/* Append USER_CLASSPATH to the default system class path */
sprintf(classpath, "%s%c%s",
vm_args.classpath, PATH_SEPARATOR, USER_CLASSPATH);
vm_args.classpath = classpath;
/* Create the Java VM */
res = JNI_CreateJavaVM(&jvm, &env, &vm_args);
#endif /* JNI_VERSION_1_2 */
if (res < 0) {
fprintf(stderr, "Can't create Java VM\n");
exit(1);
}
cls = (*env)->FindClass(env, "Prog");
if (cls == NULL) {
goto destroy;
}
mid = (*env)->GetStaticMethodID(env, cls, "main",
"([Ljava/lang/String;)V");
if (mid == NULL) {
goto destroy;
}
jstr = (*env)->NewStringUTF(env, " from C!");
if (jstr == NULL) {
goto destroy;
}
stringClass = (*env)->FindClass(env, "java/lang/String");
args = (*env)->NewObjectArray(env, 1, stringClass, jstr);
if (args == NULL) {
goto destroy;
}
(*env)->CallStaticVoidMethod(env, cls, mid, args);
destroy:
if ((*env)->ExceptionOccurred(env)) {
(*env)->ExceptionDescribe(env);
}
(*jvm)->DestroyJavaVM(jvm);
}
推荐答案
res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
与
with
// this should contain the path to the JVM DLL file
HINSTANCE hVM = LoadLibrary("C:\\Program Files (x86)\\Java\\jre6\\bin\\client\\jvm.dll");
if (hVM == NULL)
{
DWORD dwe = GetLastError();
return -1;
}
typedef jint (CALLBACK *fpCJV)(JavaVM**, void**, JavaVMInitArgs*);
fpCJV CreateJavaVM = (fpCJV)::GetProcAddress(hVM, "JNI_CreateJavaVM");
res = CreateJavaVM(&jvm, (void**)&env, &vm_args);
它应该工作;至少在我的系统上是这样.如果时间允许,我将继续进行调查.
it should work; at least it does on my system. I will continue to investigate further as time permits.
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