Way of converting java to c++. First create Navetive function. let's see the example.

		// has two args String data String id
    public static native void getNativeBluetoothData(String data,String id);
		

In cocos2dx we have AppActivity from the beginning. Write public static native function in AppActivity, And call this function want to call.

Then we have to create source file for native function.
In Classes/platform/android/jni

Source file name has a rule to obey. In this case.

org_cocos2dx_cpp_AppActivity.cpp

Pacage name in AppActivity is
package org.cocos2dx.cpp
so in header org_cocos2dx_cpp_

Let's write the code in org_cocos2dx_cpp_AppActivity.cpp

// 1.function
JNIEXPORT void JNICALL Java_org_cocos2dx_cpp_AppActivity_getNativeBluetoothData(JNIEnv *env,jobject thiz,jstring jsonStr,jstring id)
{
    // 2.convert string
    auto arg1 = env->GetStringUTFChars(jsonStr, nullptr);
    std::string string1 = arg1;
    env->ReleaseStringUTFChars(jsonStr, arg1);
    // arg2
    auto arg2 = env->GetStringUTFChars(id, nullptr);
    std::string string2 = arg2;
    env->ReleaseStringUTFChars(id, arg2);
    // 3.create scene from cocos2dx
    MenuScene* scene = dynamic_cast(cocos2d::CCDirector::sharedDirector()->getRunningScene());
    // 4.call c++ function
    scene->getBluetoothData(string1.c_str(),string2.c_str());
}
		

I define function two args both String
String equals jstring.
and let see another infomation.

JNI Types	Java Type
void	void
jboolean	boolean
jbyte	byte
jchar	char
jshort	short
jint	int
jlong	long
jfloat	float
jdouble	double
jobject	All Java objects
jclass	java.lang.Class objects
jstring	java.lang.String objects
jobjectArray	Array of objects
jbooleanArray	Array of booleans
jbyteArray	Array of bytes
jshortArray	Array of shorts
jintArray	Array of integers
jlongArray	Array of longs
jfloatArray	Array of floats
jdoubleArray	Array of doubles

in args have two arg not familiar.
JNIEnv *env
jobject thiz

This two need to declare to define function

Next is header file.
Name is org_cocos2dx_cpp_AppActivity.h

	#include 

	#ifndef _Included_org_cocos2dx_cpp_AppActivity
	#define _Included_org_cocos2dx_cpp_AppActivity

	extern "C" {

	JNIEXPORT void JNICALL Java_org_cocos2dx_cpp_AppActivity_getNativeBluetoothData
	   (JNIEnv* env,jobject thiz,jstring jsonStr,jstring id);

	#endif

In Header file needs JNIEXPORT in header.
and JNICALL ahead of function call.