libconfig++示例详解

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libconfig++(http://www.hyperrealm.com/libconfig/)是一个用于处理结构化配置文件的简单库。libconfig++的配置的文件格式非常简洁，可读性也非常的好，而且是type-aware，普通的配置文件读取后存取的类型为字符串，libconfig++可以“识别”整形的配置。libconfig++的配置形式也非常的灵活。此外，libconfig++还可以修改配置文件。

安装

安装包：libconfig-1.5.tar.gz安装过程：解压，配置，编译，安装//解压安装包tar -zxvf libconfig-1.5.tar.gz //安装前的引导配置，默认安装到/usr/local，可以通过./configure --prefix=PREFIX进行修改，也可以修改脚本参数ac_default_prefix的值cd libconfig-1.5; ./configure //编译源码make//安装前的检查make check//安装make install

使用说明
所需头文件libconfig.h++，编译时需要链接动态库libconfig++

class LIBCONFIGXX_API Config{public:    Config();  //默认构造函数    virtual ~Config(); //析构函数    ...    void read(FILE *stream); //以文件流的方式读取配置    void write(FILE *stream) const;//以文件流的方式修改配置    void readFile(const char *filename); //读取指定文件名的配置    void writeFile(const char *filename);//修改指定文件名的配置    Setting & lookup(const char *path) const; //    inline Setting & lookup(const std::string &path) const    { return(lookup(path.c_str())); }    bool exists(const char *path) const; //判断是否存在某项配置名    inline bool exists(const std::string &path) const    { return(exists(path.c_str())); }    //查找指定节点的值    bool lookupValue(const char *path, bool &value) const;    bool lookupValue(const char *path, int &value) const;    bool lookupValue(const char *path, unsigned int &value) const;    ...    Setting & getRoot() const;//获取配置的根节点    ...private:    ...    config_t *_config;    Setting::Format _defaultFormat;    //禁止拷贝和赋值    Config(const Config& other); // not supported    Config& operator=(const Config& other); // not supported};

//获取/修改配置class LIBCONFIGXX_API Setting{friend class Config;...public:    virtual ~Setting();    inline Type getType() const { return(_type); }    Setting & lookup(const char *path) const;    inline Setting & lookup(const std::string &path) const    { return(lookup(path.c_str())); }    Setting & operator[](const char *name) const;    Setting & operator[](int index) const;    //从readFile的结果中查找path的值，并将其赋给指定的类型vlaue    bool lookupValue(const char *name, bool &value) const;    bool lookupValue(const char *name, int &value) const;    bool lookupValue(const char *name, unsigned int &value) const;    bool lookupValue(const char *name, long long &value) const;    bool lookupValue(const char *name, unsigned long long &value) const;    ...    //用于添加指定类型的节点     Setting & add(const char *name, Type type);    inline Setting & add(const std::string &name, Type type)    { return(add(name.c_str(), type)); }    Setting & add(Type type);    bool exists(const char *name) const;    //判断某项配置是否存在    inline bool exists(const std::string &name) const    { return(exists(name.c_str())); }    ...private:    config_setting_t *_setting;    ...    Setting(const Setting& other); // not supported    Setting& operator=(const Setting& other); // not supported};

//其他相关迭代器class SettingIterator;class SettingConstIterator;各种异常捕获类class SettingTypeException;class SettingNotFoundException;class SettingNameException;class FileIOException;class ParseException;

示例代码
下面给出示例代码，代码中先对配置文件进行读取，最后进行修改，涉及常用的各种类型。

#include <iostream>#include <string>#include <vector>#include <map>#include "libconfig.h++"using namespace std;int main(){    libconfig::Config mConfig;    string strConfPath = "./example.cfg";    //解读配置文件    try    {        mConfig.readFile(strConfPath.c_str());    }    catch(libconfig::FileIOException &e)    {        cout<<"read file [ "<<strConfPath<< " ] FileIOException"<<endl;        return -1;    }    catch(libconfig::ParseException &e)    {        cout<<"read file [ "<<strConfPath<< " ],ParaseException: "<<e.getError()<<",line:"<<e.getLine()<<endl;        return -1;    }    catch(...)    {        cout<<"read file ["<<strConfPath<< " ] unknown exception"<<endl;        return -1;    }    //int     try    {        int num = mConfig.lookup("NUMBER");        cout<<"Number:"<<num<<endl;    }    catch(...)    {        cout<<"Get Number from "<<strConfPath<<" failed ..."<<endl;    }    //string     try    {        string str = mConfig.lookup("STRING");        //or        mConfig.lookupValue("STRING",str);        cout<<"String:"<<str<<endl;    }    catch(...)    {        cout<<"Get String from "<<strConfPath<<" failed ..."<<endl;    }    //Array     try    {        const libconfig::Setting &root = mConfig.getRoot();        const libconfig::Setting &arr = root["ARRAY"];        int cnt = arr.getLength();        vector<string> vs;        for(int i = 0 ; i < cnt ;++i)        {            string tmp = arr[i];            vs.push_back(tmp);            cout<<"Array["<<i<<"]:"<<tmp<<endl;        }    }    catch(...)    {        cout<<"Get Array from "<<strConfPath<<" failed ..."<<endl;    }    //Map     try    {        const libconfig::Setting &root = mConfig.getRoot();        const libconfig::Setting &maps = root["MAP"];        int cnt = maps.getLength();        int key;        string value;        map<int,string> mi;        for(int i = 0 ; i < cnt ;++i)        {            const libconfig::Setting &tmp = maps[i];            tmp.lookupValue("key",key);            tmp.lookupValue("value",value);            mi.insert(make_pair(key,value));            cout<<"Map["<<i<<"]:"<<key<<"->"<<value<<endl;        }    }    catch(...)    {        cout<<"Get Map from "<<strConfPath<<" failed ..."<<endl;    }    libconfig::Setting &root = mConfig.getRoot();    //增加一行整数配置    root.add("aaa", libconfig::Setting::TypeInt)=95;    //增加一行字符串配置    root.add("bbb", libconfig::Setting::TypeString)="add string";    //增加数组    libconfig::Setting &array = root.add("array", libconfig::Setting::TypeArray);    for(int i = 0; i < 10; ++i)        array.add(libconfig::Setting::TypeInt) = 10 * i;    // Add some settings to the configuration.    libconfig::Setting &address = root.add("address", libconfig::Setting::TypeGroup);    address.add("city", libconfig::Setting::TypeString) = "Nanjing";    address.add("province", libconfig::Setting::TypeString) = "JS";    // Write out the new configuration.    try    {        mConfig.writeFile(strConfPath.c_str());        cout << "New configuration successfully written to: " << strConfPath << endl;    }    catch( libconfig::FileIOException &fioex)    {        cerr << "I/O error while writing file: " << strConfPath << endl;        return(-1);    }    return 0;}

运行结果

[root@localhost linconfig]# g++ -g main.cpp -lconfig++ -o run[root@localhost linconfig]# ./runNumber:100String:hello worldArray[0]:appleArray[1]:bananaArray[2]:orangeMap[0]:100->hundredMap[1]:1000->thousandNew configuration successfully written to: ./example.cfg新增的配置会被写到example.cfg中

本文对libconfig++做了简单的介绍，对于其中重要的几个类进行了概要的说明，然而给出了相关使用示例，示例涉及常用的操作，可以被应用到工程中。

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