I got 2 projects. both are created in Netbeans IDE on Ubuntu 64 bit.
first, my .so project implements calling Java function from its c++ codes. and my console application try to call functions in .so file.
I got an error as following when I compiles and run:
/home/online0227/desktop/jvm run/dist/Debug/GNU-Linux-x86/jvm_run: symbol lookup error: ./libjvm_dll.so: undefined symbol: JNI_CreateJavaVM
How to resolve this?
I included include path to my .so project. Here is what my netbeans shows on its build output when I compile .so project:
g++ -c -g -I/home/online0227/jdk1.7.0_25_x64/include/linux -I/home/online0227/jdk1.7.0_25_x64/include -fPIC -MMD -MP -MF build/Debug/GNU-Linux-x86/_ext/1117207477/testlib.o.d -o build/Debug/GNU-Linux-x86/_ext/1117207477/testlib.o /home/online0227/desktop/jvm\ dll/testlib.cpp
g++ -o dist/Debug/GNU-Linux-x86/libjvm_dll.so build/Debug/GNU-Linux-x86/_ext/1117207477/testlib.o -shared -fPIC
this .so compiles very well and produces .so file.
And here is what my Netbeans shows when I compile my main console application:
g++ -c -g -I/home/online0227/jdk1.7.0_25_x64/include/linux -I/home/online0227/jdk1.7.0_25_x64/include -MMD -MP -MF build/Debug/GNU-Linux-x86/main.o.d -o build/Debug/GNU-Linux-x86/main.o main.cpp
g++ -o dist/Debug/GNU-Linux-x86/jvm_run build/Debug/GNU-Linux-x86/main.o -L/home/online0227/jdk1.7.0_25_x64/jre/lib/amd64/server -ldl -ljvm
It also compiles very well and run.
But the problem is I get an error message when I try to create Java Virtual Machine, "JNI_CreateJavaVM(&jvm, reinterpret_cast(&env), &vm_args)".
And following are all my source codes,
for .so project's testLib.h:
#ifndef TESTLIB_H
#define TESTLIB_H
class TestLib : public TestVir
{
public:
void init();
int createJVM();
};
#endif
for .so project's testVir.h:
#ifndef TESTVIR H
#define TESTVIR_H
class TestVir
{
public:
virtual void init()=0;
virtual int createJVM()=0;
};
#endif
for .so project's testLib.cpp:
#include <iostream>
#include <jni.h>
#include <cassert>
#include "testVir.h"
#include "testLib.h"
using namespace std;
void TestLib::init()
{
cout<<"TestLib::init: Hello World!! "<<endl ;
}
int TestLib::createJVM() {
const int kNumOptions = 3;
JavaVMOption options[kNumOptions] = {
{ const_cast<char*>("-Xmx128m"), NULL },
{ const_cast<char*>("-verbose:gc"), NULL },
{ const_cast<char*>("-Djava.class.path=."), NULL }
};
JavaVMInitArgs vm_args;
vm_args.version = JNI_VERSION_1_6;
vm_args.options = options;
vm_args.nOptions = sizeof(options) / sizeof(JavaVMOption);
assert(vm_args.nOptions == kNumOptions);
JNIEnv* env = NULL;
JavaVM* jvm = NULL;
int res = JNI_CreateJavaVM(&jvm, reinterpret_cast<void**>(&env), &vm_args);
if (res != JNI_OK) {
std::cerr << "FAILED: JNI_CreateJavaVM " << res << std::endl;
return -1;
}
jclass cls;
jmethodID mid;
jobject obj;
int staticresult = 0;
int result = 0;
long status;
if (status != JNI_ERR) {
cls = env->FindClass("PWNJavaGUI");
if (cls != 0) {
mid = env->GetStaticMethodID(cls, "main", "([Ljava/lang/String;)V");
if (mid != 0) {
env->CallStaticVoidMethod(cls, mid);
mid = env->GetStaticMethodID(cls, "isPass", "()Z"); // public static int returnCheckBox()
if (mid != 0) {
while (env->CallStaticBooleanMethod(cls, mid) == 0) {
// Do nothing but just wait until the user select game start button //
}
} else {
// Log("Error : env->GetStaticMethodID for isLoop");
return 0;
}
} else {
// Log("Error : env->GetStaticMethodID for main");
return 0;
}
} else {
// Log("Error : env->FindClass");
return 0;
}
}
return 1;
jvm->DestroyJavaVM();
return 0;
}
//Define functions with C symbols (create/destroy TestLib instance).
extern "C" TestLib* create()
{
return new TestLib;
}
extern "C" void destroy(TestLib* Tl)
{
delete Tl ;
}
And Lastly, Here is my main console application, main.cpp:
#include<iostream>
#include <stdio.h>
#include<dlfcn.h>
#include "testVir.h"
using namespace std;
int main()
{
void *handle;
handle = dlopen("./libjvm_dll.so", RTLD_LAZY);
if (!handle)
{
printf("The error is %s", dlerror());
}
typedef TestVir* create_t();
typedef void destroy_t(TestVir*);
create_t* creat=(create_t*)dlsym(handle,"create");
destroy_t* destroy=(destroy_t*)dlsym(handle,"destroy");
if (!creat)
{
cout<<"The error is %s"<<dlerror();
}
if (!destroy)
{
cout<<"The error is %s"<<dlerror();
}
TestVir* tst = creat();
tst->init();
tst->createJVM();
destroy(tst);
return 0 ;
}
