Question

尝试这个修改后的示例，我的Java代码依赖于其他库，这些库已添加到C ++应用程序的根目录中的libs文件夹中。

但是，

jclass mClass = env-> FindClass（“ MyClass”）;

返回空值

我怀疑是问题所在

options [0] .optionString =“ -Djava.class.path =。; ./ libs / *。jar”;

因此，我的MyClass.class与C ++解决方案处于同一级别，其余的依赖库位于名为/ libs的文件夹中。

当我使用没有依赖性的java示例类时，发现该类没有问题。

int main()
{

using namespace std;

// Pointer to the JVM (Java Virtual Machine)
JavaVM *jvm;

// Pointer to native interface
JNIEnv *env;

//==================== prepare loading of Java VM ============================

// Initialization arguments
JavaVMInitArgs vm_args;

// JVM invocation options
JavaVMOption* options = new JavaVMOption[1];

// where to find java .class
options[0].optionString = "-Djava.class.path=.;./libs/*.jar";

// minimum Java version
vm_args.version = JNI_VERSION_1_6;

// number of options
vm_args.nOptions = 1;

vm_args.options = options;

// invalid options make the JVM init fail
vm_args.ignoreUnrecognized = false;

//================= load and initialize Java VM and JNI interface ===============

jint rc = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
delete options;

if (rc != JNI_OK)
{
    if (rc == JNI_EVERSION)
        cerr << "FATAL ERROR: JVM is outdated and doesn't meet requirements" << endl;
    else if (rc == JNI_ENOMEM)
        cerr << "FATAL ERROR: not enough memory for JVM" << endl;
    else if (rc == JNI_EINVAL)
        cerr << "FATAL ERROR: invalid argument for launching JVM" << endl;
    else if (rc == JNI_EEXIST)
        cerr << "FATAL ERROR: the process can only launch one JVM an not more" << endl;
    else
        cerr << "FATAL ERROR:  could not create the JVM instance (error code " << rc << ")" << endl;

    cin.get();
    exit(EXIT_FAILURE);
}

jint ver = env->GetVersion();
cout << "JVM load succeeded. \nVersion ";
cout << ((ver >> 16) & 0x0f) << "." << (ver & 0x0f) << endl;

//========== Find Class ==========================

// Try to find the class 
jclass mClass = env->FindClass("MyClass");
if (mClass == nullptr)
{
    cerr << "ERROR: class not found !";
    exit(EXIT_FAILURE);
}

cout << "Class MyTest found" << endl;

JNI-从C ++调用Java，找不到类

0 个答案: