C++からJavaを呼び出す

  1
  2
  3
  4
  5
  6

public class Test {
    public static String run()
    {
        return "Hello world!";
    }
}

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19

    JNIEnv *env;
    JavaVM *jvm;
 
        JavaVMOption options[1];
    options[0].optionString = "-Djava.class.path=.";
 
    JavaVMInitArgs vm_args;
    vm_args.version = JNI_VERSION_1_6;
    vm_args.options = options;
    vm_args.nOptions = 1;
    //vm_args.ignoreUnrecognized = true;
 
        int res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
    if(res){
        cout << "cannot run JavaVM : " << res << endl;
        return 1;
    }

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14

        jclass cls = env->FindClass("Test");
    if(cls == 0){
        cout << "could not found class : Test" << endl;
        return 1;
    }
 
        jmethodID cns = env->GetMethodID(cls, "<init>", "()V");
    if(cns == NULL){
        cout << "could not get <init> method." << endl;
        return 1;
    }
    jobject obj = env->NewObject(cls, cns);

  1
  2
  3
  4
  5
  6
  7

            jmethodID mid = env->GetStaticMethodID(cls, "run", "()Ljava/lang/String;");
    if(mid == NULL){
        cout << "could not get method : " << "run" << endl;
        return 1;
    }

  1

    jstring jstr = (jstring)(env->CallObjectMethod(obj, mid));

  1
  2
  3
  4
  5
  6

        const char* cstr = env->GetStringUTFChars(jstr, 0);
    char *str = strdup(cstr);
    env->ReleaseStringUTFChars(jstr, cstr);
 
    cout << str << endl;

  1
  2
  3
  4
  5
  6

        res = jvm->DestroyJavaVM();
    if(res){
        cout << "could not destroy JavaVM : " << res << endl;
        return 1;
    }