错误request for member 'GetByteArrayElements' in something is not a structure or union
或错误too few arguements to function (*env)->GetByteArrayElements
原因:在C的定义中,env是一个两级指针,而在C++的定义中,env是个一级指针
只有C++时才用: jbyte *arr = env-> GetByteArrayElements(jarr, 0);
在C中的写法应该是:jbyte * arr = (*env)-> GetByteArrayElements(env, jarr, NULL);