Why can't I build up a VM when calling JNI_CreateJavaVM?

Question

Hello,everyone,I got a new question,I want to call java in linux redhat 7.3,but it is strange that I failed, though my code seems quite right,please :
#include "jni.h"
#include "dlfcn.h"
#include "iostream.h"
#include "string.h"
#define MAX_PATH 266
typedef jint (* JNI_CREATEJAVAVM)(JavaVM **pvm, void ** penv, void *args);
JavaVM *jvm;
main()
     char szJvm[MAX_PATH]="/usr/java/j2re1.4.0_01/lib/i386/client/libjvm.so";
//I will load libjvm.so with dlopen later
//to receive JreDir
     jclass cls;
jmethodID mid;
     int result;
     JavaVMInitArgs vm_args;
     JavaVMOption options[2];
     jint ret = -1;
     void *hLib;
     char *error=0;
     JNI_CREATEJAVAVM pfCreateJavaVM = 0;
     JNIEnv *env;
     hLib = dlopen(szJvm,RTLD_LAZY);
     if(hLib == 0)
          cout<<"Can not load library libjvm.so of Jre!"<<endl;
          return false;
     else
     cout<<"libjvm.so has been loaded in"<<endl;
     options[0].optionString = "-Djava.compiler=NONE";
     options[1].optionString = "-Djava.class.path=.";
     vm_args.version = JNI_VERSION_1_4;
     vm_args.options = options;
     vm_args.nOptions = 2; //element number of options[4]
     vm_args.ignoreUnrecognized = true;
     /*Create Java VM*/
     pfCreateJavaVM=(JNI_CREATEJAVAVM)dlsym(hLib, "JNI_CreateJavaVM");
     error=dlerror();
     if(error) //error
          //Can't Get JNI_CreatJavaVM address
          cout<<"Can not find JNI_CreatJavaVM function in libjvm.so"<<endl;
          return false;
     else
          //jvm receive the VM being created
          //env is the environment which contains all methods of java class
          ret = (*pfCreateJavaVM)(&jvm,(void**)&env,&vm_args);
     if (ret < 0)
          //failed to create VM
cout<<"Can not create Java VM"<<endl;
return false;
     else
     cout<<"Virtual machine has been set up"<<endl;
And I compile it like this:
g++ Send.cpp -rdynamic -ldl
Then when I run it: ./a.out
it shows error message:
libjvm.so has been loaded in
Error occurred during initialization of VM
Unable to load native library: libjvm.so: cannot open shared object file: No
such file or directory
I don't know what has happened.Help me please,thank you!

Answer 1

Asimov,
I have worked with JNI on OS/2 and all I can suggest is the following points...
Hello,everyone,I got a new question,I want to call
java in linux redhat 7.3,but it is strange that I
failed, though my code seems quite right,please :
#include "jni.h"
#include "dlfcn.h"
#include "iostream.h"
#include "string.h"
#define MAX_PATH 266Make this "#define MAX_PATH 1024". My code would not work with this path set to anything else. It may be OS/2 related, but try this anyway.
>
typedef jint (* JNI_CREATEJAVAVM)(JavaVM **pvm, void
** penv, void *args);
JavaVM *jvm;
main()
char
szJvm[MAX_PATH]="/usr/java/j2re1.4.0_01/lib/i386/clien
/libjvm.so";
//I will load libjvm.so with dlopen later
//to receive JreDir
     jclass cls;
jmethodID mid;
     int result;
     JavaVMInitArgs vm_args;
     JavaVMOption options[2];
     jint ret = -1;
     void *hLib;
     char *error=0;
     JNI_CREATEJAVAVM pfCreateJavaVM = 0;
     JNIEnv *env;
     hLib = dlopen(szJvm,RTLD_LAZY);
     if(hLib == 0)
cout<<"Can not load library libjvm.so of
f Jre!"<<endl;
          return false;
     else
     cout<<"libjvm.so has been loaded in"<<endl;
     options[0].optionString = "-Djava.compiler=NONE";
     options[1].optionString = "-Djava.class.path=.";
     vm_args.version = JNI_VERSION_1_4;
     vm_args.options = options;
vm_args.nOptions = 2; //element number of
options[4]
     vm_args.ignoreUnrecognized = true;
     /*Create Java VM*/
     You have configured some 'user' options here but you must get the 'system arguments' for the JVM also.
Make a call to 'JNI_GetDefaultJavaVMInitArgs( &vm_args )', then pass 'vm_args' into your JNI_CREATEJAVAVM function later.
pfCreateJavaVM=(JNI_CREATEJAVAVM)dlsym(hLib,
, "JNI_CreateJavaVM");
     error=dlerror();
     if(error) //error
          //Can't Get JNI_CreatJavaVM address
cout<<"Can not find JNI_CreatJavaVM function in
n libjvm.so"<<endl;
          return false;
     else
          //jvm receive the VM being created
//env is the environment which contains all methods
s of java class
ret =
= (*pfCreateJavaVM)(&jvm,(void**)&env,&vm_args);
     if (ret < 0)
          //failed to create VM
cout<<"Can not create Java VM"<<endl;
return false;
     else
     cout<<"Virtual machine has been set up"<<endl;
And I compile it like this:
g++ Send.cpp -rdynamic -ldl
Then when I run it: ./a.out
it shows error message:
libjvm.so has been loaded in
Error occurred during initialization of VM
Unable to load native library: libjvm.so: cannot
t open shared object file: No
such file or directory
I don't know what has happened.Help me please,thank
you!
Try those small things and let me know what it returns.
Bryan Galvin.
Software Engineer.