在一般项目中经常会用到配置文件配置一些系统参数，比如网关的端口号、memcache、redis等配置参数，数据库的ip地址、端口号、用户名密码等。 在JAVA中有properties文件读取类。 c++中有ini的读取实现，注册表的读取实现，普通文件读取等实现， 我们项目中使用的类似ini配置文件，支持分区配置参数。

配置文件如下：

实现

代码实现如下：

configure.h

#ifndef GW_CONFIGURE_H_
#define GW_CONFIGURE_H_#include <string>
#include <map>
#include <stdint.h>#include "base/basic_types.h"
namespace gateway {class Configure { public:	Configure();	~Configure();		int Init(const std::string& file);
	std::string GetValueAsString(const std::string& group,
								 const std::string& key,
								 const std::string& default_value) const;
	uint32_t GetValueAsUint32(const std::string& group,
							const std::string& key,
							uint32_t default_value) const;
	double GetValueAsDouble(const std::string& group,
							const std::string& key,
							double default_value) const;
	bool GetValueAsBool(const std::string& group,
						  const std::string& key,
						  bool  default_value) const;
 private:	 private:	std::map<std::string, std::map<std::string, std::string> > items_;
	DISALLOW_COPY_AND_ASSIGN(Configure);};} // namespace gateway
#endif // GW_CONFIGURE_H_

configure.h代码

configure.cpp代码如下：

#include <stdio.h>
#include <stdlib.h>#include <IOStream>#include "gateway/configure.h"
namespace gateway {class ConfigFile {public:	ConfigFile();	~ConfigFile();	int Init(const char* file);
	int ParseFile(std::map<std::string, std::map<std::string, std::string> >& group_items);private:	int GetLine(std::string& line);	int GetKeyAndValue(const std::string& line, std::string& key, std::string& value);
	void Trim(std::string& str);
private:	FILE* pf_;	enum {
		kErrorRow    = 0,
		kEmptyRow,		kGroupRow,		kValueRow,	};	DISALLOW_COPY_AND_ASSIGN(ConfigFile);};ConfigFile::ConfigFile() : pf_(NULL) {}ConfigFile::~ConfigFile() {	if (pf_ != NULL) {
		fclose(pf_);	}}int ConfigFile::Init(const char* file) {
	pf_ = fopen(file, "r");
	if (pf_ == NULL) return RESULT_ERROR;
	return RESULT_OK;
}void ConfigFile::Trim(std::string& str) {
	size_t size = str.size();
	if (size == 0) return ;
	size_t begin = 0;
	while (begin < size && str[begin] == ' ') begin++;
	size_t end = size - 1;
	while (end > begin && str[end] == ' ') end--;
	if (end >= begin) {
		str = str.substr(begin, end + 1 - begin);
	} else {
		str = "";
	}}int ConfigFile::GetLine(std::string& line) {	const int kLen = 512;
	char buf[kLen] = {0};
	if (fgets(buf, kLen, pf_) != NULL) {
		line = buf;		Trim(line);		if (line.length() < 2) return kEmptyRow;
		if (line[0] == '#') return kEmptyRow;
				std::string s = line.substr(line.length() - 2);
		if (s == "nr") {
			line = line.substr(0, line.length() - 2);
		}		s = line.substr(line.length() - 1);
		if (s == "r" || s == "n") {
			line = line.substr(0, line.length() - 1);
		}		if (line.length() == 0) return kEmptyRow;
		if ((line[0] == '[') && (line[line.length() - 1] == ']')) {
			line = line.substr(1, line.length() - 2);
			return kGroupRow;
		}		return kValueRow;
	}	//包括
	return kErrorRow;
}
int ConfigFile::GetKeyAndValue(const std::string& line, std::string& key, std::string& value) {
	int pos = line.find_first_of("=");
	if (pos < 0) return RESULT_ERROR;
	key = line.substr(0, pos);
	Trim(key);
	value = line.substr(pos + 1);
	Trim(value);
	return RESULT_OK;
}
int ConfigFile::ParseFile(std::map<std::string, std::map<std::string, std::string> >& group_items) {
	fseek(pf_, 0, SEEK_SET);
	int type = kErrorRow;
	std::string line;	
	std::string group;
	std::string key;
	std::string value;
	while ((type = GetLine(line)) != kErrorRow) {
		//处理行
		if (type == kGroupRow) {
			group = line;
			group_items[group] = std::map<std::string, std::string>();
		} else if (type == kValueRow){
			//找到key and value
			if (GetKeyAndValue(line, key, value) == RESULT_OK) {
				group_items[group][key] = value;
			}
		}
	}
	return RESULT_OK;
}
//=============================
Configure::Configure() {
}
	
Configure::~Configure() {
}
	
int Configure::Init(const std::string& file) {
	ConfigFile config;
	int result = config.Init(file.c_str());
	if (result != RESULT_OK) return result;
	//解析具体配置文件:
	result = config.ParseFile(items_);
	return result;
}
std::string Configure::GetValueAsString(const std::string& group,
																				const std::string& key,
																				const std::string& default_value) const {
	std::string result = default_value;
	std::map<std::string, std::map<std::string, std::string> >::const_iterator g_it = items_.find(group);
	if (g_it != items_.end()) {
		std::map<std::string, std::string>::const_iterator it = g_it->second.find(key);
		if (it != g_it->second.end()) {
			result = it->second;
		}
	}
	return result;
}
	
uint32_t Configure::GetValueAsUint32(const std::string& group,
																	 const std::string& key,
																	 uint32_t default_value) const {
	uint32_t result = default_value;
	std::map<std::string, std::map<std::string, std::string> >::const_iterator g_it = items_.find(group);
	if (g_it != items_.end()) {
		std::map<std::string, std::string>::const_iterator it = g_it->second.find(key);
		if (it != g_it->second.end()) {
			result = atoi(it->second.c_str());
		}
	}
	return result;
}
	
double Configure::GetValueAsDouble(const std::string& group,
																	 const std::string& key,
																	 double default_value) const {
	double result = default_value;
	std::map<std::string, std::map<std::string, std::string> >::const_iterator g_it = items_.find(group);
	if (g_it != items_.end()) {
		std::map<std::string, std::string>::const_iterator it = g_it->second.find(key);
		if (it != g_it->second.end()) {
			result = atof(it->second.c_str());
		}
	}
	return result;
}
	
bool Configure::GetValueAsBool(const std::string& group,
															 const std::string& key,
															 bool  default_value) const {
	bool result = default_value;
	std::map<std::string, std::map<std::string, std::string> >::const_iterator g_it = items_.find(group);
	if (g_it != items_.end()) {
		std::map<std::string, std::string>::const_iterator it = g_it->second.find(key);
		if (it != g_it->second.end()) {
			result = (it->second == "1");
		}
	}
	return result;
}
} // namespace gateway

案例

使用样例如下：

int gw_set_opt(gateway::Gateway::Options& options, const std::string& file) {
	gateway::Configure config;
	if (config.Init(file) != RESULT_OK) {
		return RESULT_ERROR;
	}	options.unit_io_nevents = config.GetValueAsUint32("unit", "io_nevents", options.unit_io_nevents);
	options.unit_reactor_timeout = config.GetValueAsUint32("unit", "reactor_timeout", options.unit_reactor_timeout); 
	options.unit_timer_nevents = 0;
	options.unit_conn_timeout = config.GetValueAsUint32("unit", "conn_timeout", options.unit_conn_timeout);
	options.unit_listen_addr = config.GetValueAsString("unit", "listen_addr", options.unit_listen_addr);