jint 转 jstring 

jint cno=2;

char buf[64];

sprintf(buf, "%d",cno);

std::string namestd1= "";

namestd1.append(buf);

 jstring 转char

const char * str = env->GetStringUTFChars(name,0);

char c[120] = "";//调用c++拼接字符函数strcat(c,str);

//释放env->ReleaseStringUTFChars(name,str);

或者

char names[40] ;

sprintf(names, "%s", name);

puts(names);

 char  转 jstring

char s[256] = {0};

strcpy(s, namestd.c_str());

jstring a=env->NewStringUTF(namestd.c_str())