有很多的时候 会出现没有用的优盘路径 如果代码中写的是绝对路径 就有可能读不到优盘的内容 ，以下代码就是可以解决这样的问题 我已经封装成一个类
upanpath.h
#ifndef UPANPATH_H
#define UPANPATH_H #include <dirent.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <string.h>
#include <vector>
#include <iostream>
#include <unistd.h> using namespace std; class UPanPath
{
public:
UPanPath(string file_name,string UPan_name,string target_file_name);
~UPanPath();
string fileName;
string UPanName;
string targetFileName;
vector<string> getFoldernames( const string dir_name, const string filter1);
bool dirIsExit( const string dir_name );
string getFilePath();
};
#define NOROBOT "no find ROBOT file"
#define NOEFFECTIVE "no find effective file"
#endif // UPANPATH_H
upanpath.cpp
#include "upanpath.h" UPanPath::UPanPath(string file_name,string UPan_name,string target_file_name)
{
this->fileName = file_name ;
this->UPanName = UPan_name;
this->targetFileName = target_file_name;
}
/* Get all the files in the folder dir_name , do not show the directories ! */
bool UPanPath::dirIsExit(const string dir_name)
{
// check the parameter !
if( "" == dir_name )
{
cout<<" dir_name is null ! "<<endl;
return false;
}
// check if dir_name is a valid dir
struct stat s;
lstat( dir_name.c_str() , &s );
if( ! S_ISDIR( s.st_mode ) )
{
cout<<dir_name << " is not a valid directory !"<<endl;
return false;
}
return true; }
/* Get all the files in the folder dir_name , do not show the directories !
* 此函数可以得到指定目录下的所有文件和文件夹名，可以对其进行筛选，只要文件，然后再根据两个过滤器依次进行筛选，得到指定的文件。
*/
vector<string> UPanPath::getFoldernames( const string dir_name, const string filter)
{
vector<string> dirs;
// check the parameter !
if( "" == dir_name )
{
cout<<" dir_name is null ! "<<endl;
return dirs;
} // check if dir_name is a valid dir
struct stat s;
lstat( dir_name.c_str() , &s );
if( ! S_ISDIR( s.st_mode ) )
{
cout<<dir_name << " is not a valid directory !"<<endl;
return dirs;
} struct dirent * filename; // return value for readdir()
DIR * dir; // return value for opendir()
dir = opendir( dir_name.c_str() );
if( NULL == dir )
{
cout<<"Can not open directory "<<dir_name<<endl;
return dirs;
}
cout<<"Open the directory successfully!"<<endl; string path;
if( dir_name.substr(dir_name.length()-, ) != "/" )
path = dir_name + "/";
else
path = dir_name; struct stat s_buf;
string dir_tmp;
/* read all the files in the dir ~ */
while( ( filename = readdir(dir) ) != NULL )
{
dir_tmp = filename ->d_name;
// get rid of "." and ".."
if( "." == dir_tmp || ".." == dir_tmp )
continue; /*获取文件信息，把信息放到s_buf中*/
stat( (path + dir_tmp).c_str(), &s_buf );
/*判断是否目录*/
if( !S_ISDIR(s_buf.st_mode) )
continue; if("" != filter)
{
if((int)dir_tmp.find(filter) >= )
dirs.push_back(dir_tmp);
}
else
dirs.push_back(dir_tmp); }
return dirs;
}
string UPanPath::getFilePath()
{
vector<string> dir_f = UPanPath::getFoldernames(UPanPath::fileName,UPanPath::UPanName);
cout << "文件的个数："<<dir_f.size() << endl;
string faces_dir = "";
vector<string> upan_name ;
for(int i=; i< dir_f.size(); i++)
{
cout << "dir_f[" << i << "]: " << dir_f[i] << endl;
string dir_tmp = UPanPath::fileName; //+"/"+ dir_f[i];
dir_tmp += "/";
dir_tmp += dir_f[i];
dir_tmp += "/";
dir_tmp += UPanPath::targetFileName;
cout << dir_tmp <<endl;
if( != system( ("cd " + dir_tmp).c_str() ) )
{
if( == system( ("sudo rm -rf " + dir_tmp).c_str() ) )
cout << "Delet invalid Upan folder [ " << dir_tmp << " ] successfully..." << endl;
else
cout << "Failed to delete invalid Upan folder [ " << dir_tmp << " ] ..." << endl;
}
else
upan_name.push_back(dir_f[i]);
} int len = upan_name.size();
if ( == len )
{
cout << "Don't find the Upan [ ROBOT ], please insert the Upan first ..." << endl;
return NOROBOT;
} else
{
for (int i=; i<len; i++)
{
string dir_tmp = UPanPath::fileName;
dir_tmp += "/";
dir_tmp += upan_name[i];
dir_tmp += "/";
dir_tmp += UPanPath::targetFileName;
cout << dir_tmp <<endl;
if(UPanPath::dirIsExit(dir_tmp))
{
faces_dir = dir_tmp;
break;
}
}
if("" == faces_dir)
{
cout << "Don't find the folder [ faces ] in the Upan ..." << endl;
return NOEFFECTIVE;
} else
{
cout << "Find the Upan faces folder [ " << faces_dir << " ] ..." << endl;
return faces_dir;
}
}
}
UPanPath::~UPanPath()
{
cout << "析构函数"<< endl;
}
main.cpp
#include <QCoreApplication> #include "upanpath.h" int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv); UPanPath *P = new UPanPath("/media/alvin","ROBOT","faces");
string FilePath = P->getFilePath();
cout << "effective file path :" << FilePath << endl; return a.exec();
}
可以根据函数的返回值的 不同确定什么原因导致读取失败。