C++编写Config类读取配置文件

老外写的一段代码，在Server中编写这个类读取配置文件比较实用

//Config.h
#pragma once

#include <string>
#include <map>
#include <iostream>
#include <fstream>
#include <sstream>


/*
* \brief Generic configuration Class
*
*/
class Config {
	// Data
protected:
	std::string m_Delimiter;  //!< separator between key and value
	std::string m_Comment;    //!< separator between value and comments
	std::map<std::string,std::string> m_Contents;  //!< extracted keys and values

	typedef std::map<std::string,std::string>::iterator mapi;
	typedef std::map<std::string,std::string>::const_iterator mapci;
	// Methods
public:

	Config( std::string filename,std::string delimiter = "=",std::string comment = "#" );
	Config();
	template<class T> T Read( const std::string& in_key ) const;  //!<Search for key and read value or optional default value, call as read<T>
	template<class T> T Read( const std::string& in_key, const T& in_value ) const;
	template<class T> bool ReadInto( T& out_var, const std::string& in_key ) const;
	template<class T>
	bool ReadInto( T& out_var, const std::string& in_key, const T& in_value ) const;
	bool FileExist(std::string filename);
	void ReadFile(std::string filename,std::string delimiter = "=",std::string comment = "#" );

	// Check whether key exists in configuration
	bool KeyExists( const std::string& in_key ) const;

	// Modify keys and values
	template<class T> void Add( const std::string& in_key, const T& in_value );
	void Remove( const std::string& in_key );

	// Check or change configuration syntax
	std::string GetDelimiter() const { return m_Delimiter; }
	std::string GetComment() const { return m_Comment; }
	std::string SetDelimiter( const std::string& in_s )
	{ std::string old = m_Delimiter;  m_Delimiter = in_s;  return old; }  
	std::string SetComment( const std::string& in_s )
	{ std::string old = m_Comment;  m_Comment =  in_s;  return old; }

	// Write or read configuration
	friend std::ostream& operator<<( std::ostream& os, const Config& cf );
	friend std::istream& operator>>( std::istream& is, Config& cf );

protected:
	template<class T> static std::string T_as_string( const T& t );
	template<class T> static T string_as_T( const std::string& s );
	static void Trim( std::string& inout_s );


	// Exception types
public:
	struct File_not_found {
		std::string filename;
		File_not_found( const std::string& filename_ = std::string() )
			: filename(filename_) {} };
		struct Key_not_found {  // thrown only by T read(key) variant of read()
			std::string key;
			Key_not_found( const std::string& key_ = std::string() )
				: key(key_) {} };
};


/* static */
template<class T>
std::string Config::T_as_string( const T& t )
{
	// Convert from a T to a string
	// Type T must support << operator
	std::ostringstream ost;
	ost << t;
	return ost.str();
}


/* static */
template<class T>
T Config::string_as_T( const std::string& s )
{
	// Convert from a string to a T
	// Type T must support >> operator
	T t;
	std::istringstream ist(s);
	ist >> t;
	return t;
}


/* static */
template<>
inline std::string Config::string_as_T<std::string>( const std::string& s )
{
	// Convert from a string to a string
	// In other words, do nothing
	return s;
}


/* static */
template<>
inline bool Config::string_as_T<bool>( const std::string& s )
{
	// Convert from a string to a bool
	// Interpret "false", "F", "no", "n", "0" as false
	// Interpret "true", "T", "yes", "y", "1", "-1", or anything else as true
	bool b = true;
	std::string sup = s;
	for( std::string::iterator p = sup.begin(); p != sup.end(); ++p )
		*p = toupper(*p);  // make string all caps
	if( sup==std::string("FALSE") || sup==std::string("F") ||
		sup==std::string("NO") || sup==std::string("N") ||
		sup==std::string("0") || sup==std::string("NONE") )
		b = false;
	return b;
}


template<class T>
T Config::Read( const std::string& key ) const
{
	// Read the value corresponding to key
	mapci p = m_Contents.find(key);
	if( p == m_Contents.end() ) throw Key_not_found(key);
	return string_as_T<T>( p->second );
}


template<class T>
T Config::Read( const std::string& key, const T& value ) const
{
	// Return the value corresponding to key or given default value
	// if key is not found
	mapci p = m_Contents.find(key);
	if( p == m_Contents.end() ) return value;
	return string_as_T<T>( p->second );
}


template<class T>
bool Config::ReadInto( T& var, const std::string& key ) const
{
	// Get the value corresponding to key and store in var
	// Return true if key is found
	// Otherwise leave var untouched
	mapci p = m_Contents.find(key);
	bool found = ( p != m_Contents.end() );
	if( found ) var = string_as_T<T>( p->second );
	return found;
}


template<class T>
bool Config::ReadInto( T& var, const std::string& key, const T& value ) const
{
	// Get the value corresponding to key and store in var
	// Return true if key is found
	// Otherwise set var to given default
	mapci p = m_Contents.find(key);
	bool found = ( p != m_Contents.end() );
	if( found )
		var = string_as_T<T>( p->second );
	else
		var = value;
	return found;
}


template<class T>
void Config::Add( const std::string& in_key, const T& value )
{
	// Add a key with given value
	std::string v = T_as_string( value );
	std::string key=in_key;
	trim(key);
	trim(v);
	m_Contents[key] = v;
	return;
}

// Config.cpp

#include "Config.h"

using namespace std;


Config::Config( string filename, string delimiter,
			   string comment )
			   : m_Delimiter(delimiter), m_Comment(comment)
{
	// Construct a Config, getting keys and values from given file

	std::ifstream in( filename.c_str() );

	if( !in ) throw File_not_found( filename ); 

	in >> (*this);
}


Config::Config()
: m_Delimiter( string(1,'=') ), m_Comment( string(1,'#') )
{
	// Construct a Config without a file; empty
}



bool Config::KeyExists( const string& key ) const
{
	// Indicate whether key is found
	mapci p = m_Contents.find( key );
	return ( p != m_Contents.end() );
}


/* static */
void Config::Trim( string& inout_s )
{
	// Remove leading and trailing whitespace
	static const char whitespace[] = " \n\t\v\r\f";
	inout_s.erase( 0, inout_s.find_first_not_of(whitespace) );
	inout_s.erase( inout_s.find_last_not_of(whitespace) + 1U );
}


std::ostream& operator<<( std::ostream& os, const Config& cf )
{
	// Save a Config to os
	for( Config::mapci p = cf.m_Contents.begin();
		p != cf.m_Contents.end();
		++p )
	{
		os << p->first << " " << cf.m_Delimiter << " ";
		os << p->second << std::endl;
	}
	return os;
}

void Config::Remove( const string& key )
{
	// Remove key and its value
	m_Contents.erase( m_Contents.find( key ) );
	return;
}

std::istream& operator>>( std::istream& is, Config& cf )
{
	// Load a Config from is
	// Read in keys and values, keeping internal whitespace
	typedef string::size_type pos;
	const string& delim  = cf.m_Delimiter;  // separator
	const string& comm   = cf.m_Comment;    // comment
	const pos skip = delim.length();        // length of separator

	string nextline = "";  // might need to read ahead to see where value ends

	while( is || nextline.length() > 0 )
	{
		// Read an entire line at a time
		string line;
		if( nextline.length() > 0 )
		{
			line = nextline;  // we read ahead; use it now
			nextline = "";
		}
		else
		{
			std::getline( is, line );
		}

		// Ignore comments
		line = line.substr( 0, line.find(comm) );

		// Parse the line if it contains a delimiter
		pos delimPos = line.find( delim );
		if( delimPos < string::npos )
		{
			// Extract the key
			string key = line.substr( 0, delimPos );
			line.replace( 0, delimPos+skip, "" );

			// See if value continues on the next line
			// Stop at blank line, next line with a key, end of stream,
			// or end of file sentry
			bool terminate = false;
			while( !terminate && is )
			{
				std::getline( is, nextline );
				terminate = true;

				string nlcopy = nextline;
				Config::Trim(nlcopy);
				if( nlcopy == "" ) continue;

				nextline = nextline.substr( 0, nextline.find(comm) );
				if( nextline.find(delim) != string::npos )
					continue;

				nlcopy = nextline;
				Config::Trim(nlcopy);
				if( nlcopy != "" ) line += "\n";
				line += nextline;
				terminate = false;
			}

			// Store key and value
			Config::Trim(key);
			Config::Trim(line);
			cf.m_Contents[key] = line;  // overwrites if key is repeated
		}
	}

	return is;
}
bool Config::FileExist(std::string filename)
{
	bool exist= false;
	std::ifstream in( filename.c_str() );
	if( in ) 
		exist = true;
	return exist;
}

void Config::ReadFile( string filename, string delimiter,
					  string comment )
{
	m_Delimiter = delimiter;
	m_Comment = comment;
	std::ifstream in( filename.c_str() );

	if( !in ) throw File_not_found( filename ); 

	in >> (*this);
}

//main.cpp
#include "Config.h"
int main()
{
	int port;
	std::string ipAddress;
	std::string username;
	std::string password;
	const char ConfigFile[]= "config.txt"; 
	Config configSettings(ConfigFile);
	
	port = configSettings.Read("port", 0);
	ipAddress = configSettings.Read("ipAddress", ipAddress);
	username = configSettings.Read("username", username);
	password = configSettings.Read("password", password);
	std::cout<<"port:"<<port<<std::endl;
	std::cout<<"ipAddress:"<<ipAddress<<std::endl;
	std::cout<<"username:"<<username<<std::endl;
	std::cout<<"password:"<<password<<std::endl;
	
	return 0;
}

config.txt的文件内容：
ipAddress=10.10.90.125
port=3001
username=mark
password=2d2df5a


编译运行输出:
port:3001
ipAddress:10.10.90.125
username:mark
password:2d2df5a

这个类还有很多其他的方法，可以调用试试。

评论

2 楼 mylove2060 2013-01-08  

navylq 写道

  这代码你自己有测试么？
引用自哪里也没有说！

测过

1 楼 navylq 2012-11-26  

  这代码你自己有测试么？
引用自哪里也没有说！