ReleaseStringUTFChars对于std :: string不起作用

我在jni函数中使用了std :: string，但是我无法使用ReleaseStringUTFChars释放它.我得到的错误是:

I use std::string in my jni function, and I fail to release it using ReleaseStringUTFChars. The error I get is:

错误:没有匹配函数可调用NIEnv :: ReleaseStringUTF env-> ReleaseStringUTFChars(path，dir);

error: no matching function for call to NIEnv::ReleaseStringUTF env->ReleaseStringUTFChars(path, dir);

我知道，该函数希望获取字符串而不是字符串，但是我没有这样的变量.我该怎么办?

I understand, that instead of string, the function expects to get char, but I don't have such variable. What should I do?

这是我的jni函数:

void Java_com_example_android_OpenCVActivity_test (JNIEnv * env, jclass clazz, jstring path){

    std::string dir = env->GetStringUTFChars(path, 0);
   ....
env->ReleaseStringUTFChars(path, dir);
}