BOOST XML解析

BOOST XML解析相同Tag子节点

主要用到了BOOST_FOREACH宏，对ptree进行遍历：

int SecSrcmConf::readFromXML() {    ifstream file;    file.open(m_confFilePath.c_str(), ios::in);    if (!file.is_open()) {        cerr << "File " << m_confFilePath << " open failed" << endl;        return -1;    }    file.close();    ptree pt;    read_xml(m_confFilePath, pt, xml_parser::trim_whitespace);    parseSystemInfoFromXML(pt.get_child("SRCM.System"));    parseMMIInfoFromXML(pt.get_child("SRCM.MMI"));    BOOST_FOREACH (ptree::value_type &v, pt.get_child("SRCM")) {        string tmp;        if (v.first == "Substation") {            SrcmSubConf subConf;            subConf.m_subName = v.second.get<string>("Name");            tmp = v.second.get<string>("Protocol");            if (tmp.length()) {                if (tmp == "ext104" || tmp == "EXT104") {                    subConf.m_protocolType = PROTOCOL_EXT104;                } else if (tmp == "iec61850" || tmp == "IEC61850") {                    subConf.m_protocolType = PROTOCOL_IEC61850;                } else {                    subConf.m_protocolType = PROTOCOL_NULL;                }            }            tmp = v.second.get<string>("Compress");            if (tmp.length()) {                if (tmp == "ZIP" || tmp == "zip") {                    subConf.m_compressType = COMPRESS_ZIP;                } else if (tmp == "GZIP" || tmp == "gzip" ||                    tmp == "GZ" || tmp == "gz") {                    subConf.m_compressType = COMPRESS_GZIP;                } else {                    subConf.m_compressType = COMPRESS_NULL;                }            }            subConf.m_cimLastUpdate = str2time(                v.second.get<string>("DeviceCIMFile.LastUpdateTime"));            subConf.m_cimLastImport = str2time(                v.second.get<string>("DeviceCIMFile.LastImportTime"));            subConf.m_svgLastUpdate = str2time(                v.second.get<string>("DeviceSVGFile.LastUpdateTime"));            subConf.m_svgLastImport = str2time(                v.second.get<string>("DeviceSVGFile.LastImportTime"));            subConf.m_mapLastUpdate = str2time(                v.second.get<string>("DeviceMAPFile.LastUpdateTime"));            subConf.m_mapLastImport = str2time(                v.second.get<string>("DeviceMAPFile.LastImportTime"));            m_subConfMap.insert(pair<string, SrcmSubConf>(subConf.m_subName, subConf));        }    }    return 0;}

BOOST XML解析中文问题

ptree解析主要的xml文件的格式是utf-8格式的，如果xml文件中含有unicode如中文字符，解析出来就是乱码。解析unicode要用wptree，该类的接口均支持宽字符并且接口和ptree保持一致。要支持中文解析仅仅wptree还不够，还需要一个unicode转换器的帮助，该转换器可以实现宽字符和窄字符的转换，宽窄的互相转换函数有很多实现，不过c++11中有更简单统一的方式实现宽窄字符的转换。

c++11中宽窄字符的转换：

std::wstring_convert<std::codecvt<wchar_t,char,std::mbstate_t>> conv(newstd::codecvt<wchar_t,char,std::mbstate_t>("CHS"));//宽字符转为窄字符string str = conv.to_bytes(L"你好");//窄字符转为宽字符string wstr = conv.from_bytes(str);

boost.property_tree在解析含中文的xml文件时，需要先将该文件转换一下。boost解决方法：

#include "boost/program_options/detail/utf8_codecvt_facet.hpp"void ParseChn(){    std::wifstream f(fileName);    std::locale utf8Locale(std::locale(), new boost::program_options::detail::utf8_codecvt_facet());    f.imbue(utf8Locale); //先转换一下    //用wptree去解析    property_tree::wptree ptree;    property_tree::read_xml(f, ptree);    }

这种方法有个缺点就是要引入boost的libboost_program_options库，该库有二十多M，仅仅是为了解决一个中文问题，却要搞得这么麻烦，有点得不偿失。好在c++11提供更简单的方式，用c++11可以这样：

void Init(const wstring& fileName, wptree& ptree)    {        std::wifstream f(fileName);        std::locale utf8Locale(std::locale(), new std::codecvt_utf8<wchar_t>);        f.imbue(utf8Locale); //先转换一下        //用wptree去解析        property_tree::read_xml(f, ptree);    }

用c++11就不需要再引入boost的libboost_program_options库了，很简单。另外一种方法就是，仍然用ptree和string，只是在取出string字符串后，做一个转换为unicode的转换，就能得到中文字符串了。例如：

auto child = item.second.get_child("Scenes.Scene");auto oname = child.get_optional<string>("<xmlattr>.Name");//oname内部存了一个unicode字符串，需要将其转换为宽字符串得到中文std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;std::wstring wide = converter.from_bytes(*oname);//宽字符串转为窄字符串//std::string narrow = converter.to_bytes(L"foo");

BOOST 写入XML文件格式问题

主要使用到了boost::property_tree::xml_writer_settings。如果编译器用到了C++11，用下面的写法表示缩进两个空格：

boost::property_tree::xml_writer_settings<char> settings(' ',2);boost::property_tree::write_xml(filename, pt,std::local(),settings);

如果没有C++11特性，那么使用xml_writer_make_settings方法：

boost::property_tree::xml_writer_settings<string> settings =    bp::xml_writer_make_settings<string>(' ', 2);boost::property_tree::write_xml(xml_path, root, locale(), settings);