java jni 返回map

extern "C"jobjectJava_com_example_admin_testusecpp_MainActivity_retMap(        JNIEnv* env,        jobject /* this */) {    jclass java_cls_HashMap = env->FindClass("java/util/HashMap");    jmethodID java_mid_HashMap = env->GetMethodID(java_cls_HashMap, "<init>", "()V");    jobject  java_obj_HashMap = env->NewObject(java_cls_HashMap, java_mid_HashMap, "");    jmethodID java_mid_HashMap_put = env->GetMethodID(java_cls_HashMap, "put", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;");    env->CallObjectMethod(java_obj_HashMap, java_mid_HashMap_put, env->NewStringUTF("key"), env->NewStringUTF("value"));    return java_obj_HashMap;}