掌握了ACMXML库解析XML文件的方法后，下面来实现一个比较完整的程序。
定义基本结构
xml文件格式如下
<?xml version="1.0"?>
<root version="9" count="3" >
<file id="1">D:\test1.txt</file>
<file id="2">D:\test2.txt</file>
<file id="3">D:\test3.txt</file>
</root>
这个xml文件虽然短小，但是对于示例程序来说已经足够了。
xml文件解析后，要将解析的数据保存起来，可以定义这样两个结构：
//对应xml文件的根节点
typedef struct _ROOT
{
//版本号
int version;
//子项的数量
int count;
} ROOT; //对应xml文件的子项
typedef struct _FILE
{
int id;
//文件路径
string path;
} ROOT_FILE;
通过宏定义来指定每个节点的名字：
#define XML_ROOT "root"
#define XML_FILE "file"
#define XML_ID "id"
#define XML_VER "version"
#define XML_COUNT "count"
定义并实现两个类xml_handler、xml_parser。
xml_parser负责解析xml文件，但是它并不关心xml文件中的数据按什么样的格式保存。
而和具体的格式相关的类为xml_handler，解析xml文件后的数据会保存在这个类的实例里面。
xml_hanlder主要方法介绍
通过startElement和characters两个方法来获取数据：
virtual void startElement( const ACEXML_Char *namespaceURI, const ACEXML_Char *localName, const ACEXML_Char *qName, ACEXML_Attributes *atts )
{
//file节点
if(stricmp(localName, XML_FILE) == 0)
{
if(root_.count == files_.size())
{
return;
}
flag_ = FLAG_FILE;
ROOT_FILE* file = new ROOT_FILE();
files_.push_back(file);
for(int i=0; i<atts->getLength(); ++i)
{
const char* qname = atts->getQName(i);
if(stricmp(qname, XML_ID) == 0)
{
file->id = atoi(atts->getValue(i));
}
}
}
//root节点
else if(stricmp(localName, XML_ROOT) == 0)
{
flag_ = FLAG_ROOT;
for(int i=0; i<atts->getLength(); ++i)
{
const char* qname = atts->getQName(i);
if(stricmp(qname, XML_VER) == 0)
{
root_.version= atoi(atts->getValue(i));
}
else if(stricmp(qname, XML_COUNT) == 0)
{
root_.count = atoi(atts->getValue(i));
}
}
} } virtual void characters( const ACEXML_Char *ch, size_t start, size_t length )
{
if(flag_ == FLAG_FILE)
{
files_[files_.size() - 1]->path = ch;
}
flag_ = FLAG_NULL;
}
通过flush方法将root、file信息写入到xml文件中：
//将当前root、file信息写入到xml文件中
bool flush() const
{
ofstream ofs(filepath_.c_str(), ios_base::trunc);
if(!ofs)
{
return false;
}
ofs << "<?xml version=\"1.0\"?>" << endl;
ofs << "<" << XML_ROOT << " " << XML_VER << "=\"" << root_.version << "\" " << XML_COUNT << "=\"" << root_.count << "\" >" << endl;
for(size_t i=0; i<files_.size(); ++i)
{
ofs << "\t<" << XML_FILE << " " << XML_ID << "=\"" << files_[i]->id << "\" >" << files_[i]->path << "</" << XML_FILE << ">" << endl;
}
ofs << "</" << XML_ROOT << ">" << endl;
ofs.close();
return true;
}
通过重载操作符operator[]方法获得子项的数据：
//获取第index个ROOT_FILE子项
//如果index超出当前子项的个数，则返回0
const ROOT_FILE* operator[](size_t index) const
{
if(index >= files_.size())
{
return 0;
}
return files_[index];
}
xml_handler完整代码展示
#pragma once #include "ACEXML/common/DefaultHandler.h"
#include <string>
#include <iostream>
#include <vector>
#include <fstream>
using namespace std; //对应xml文件的根节点
typedef struct _ROOT
{
//版本号
int version;
//子项的数量
int count;
} ROOT; //对应xml文件的子项
typedef struct _FILE
{
int id;
//文件路径
string path;
} ROOT_FILE; #define XML_ROOT "root"
#define XML_FILE "file"
#define XML_ID "id"
#define XML_VER "version"
#define XML_COUNT "count" //针对某个具体的xml文件格式进行解析的类
//注意：此对象不提供多进程或多线程按序访问的功能
class xml_handler : public ACEXML_DefaultHandler
{
public:
//构造。
//@param name 字符串，输入，xml文件的路径
xml_handler(char* path): filepath_(path), flag_(0) {}
virtual ~xml_handler(){
for(size_t i=0; i<files_.size(); ++i)
{
if(files_[i])
{
delete files_[i];
files_[i] = 0;
}
}
files_.clear();
}
//获取xml文件的路径
const string& path() const
{
return filepath_;
}
//获取子项的数量，对应root.count
const size_t count() const
{
return files_.size();
}
//获取第index个ROOT_FILE子项
//如果index超出当前子项的个数，则返回0
const ROOT_FILE* operator[](size_t index) const
{
if(index >= files_.size())
{
return 0;
}
return files_[index];
}
//获取root信息
const ROOT& root() const
{
return root_;
}
//增加一个子项
//@param path 字符串，输入，文件的路径
//@param id 整形，输入，文件id
bool increase(const char* path, size_t id)
{
if(!path || *path == 0 || id == 0)
{
return false;
}
ROOT_FILE* file = new(std::nothrow)ROOT_FILE();
//申请内存失败
if(!file)
{
return false;
}
file->path = path;
file->id = id;
files_.push_back(file);
return true;
}
//将当前root、file信息写入到xml文件中
bool flush() const
{
ofstream ofs(filepath_.c_str(), ios_base::trunc);
if(!ofs)
{
return false;
}
ofs << "<?xml version=\"1.0\"?>" << endl;
ofs << "<" << XML_ROOT << " " << XML_VER << "=\"" << root_.version << "\" " << XML_COUNT << "=\"" << root_.count << "\" >" << endl;
for(size_t i=0; i<files_.size(); ++i)
{
ofs << "\t<" << XML_FILE << " " << XML_ID << "=\"" << files_[i]->id << "\" >" << files_[i]->path << "</" << XML_FILE << ">" << endl;
}
ofs << "</" << XML_ROOT << ">" << endl;
ofs.close();
return true;
}
//将当前root、file信息输出到控制台
void dump() const
{
cout << "<?xml version=\"1.0\"?>" << endl;
cout << "<" << XML_ROOT << " " << XML_VER << "=\"" << root_.version << "\" " << XML_COUNT << "=\"" << root_.count << "\" >" << endl;
for(size_t i=0; i<files_.size(); ++i)
{
cout << "\t<" << XML_FILE << " " << XML_ID << "=\"" << files_[i]->id << "\" >" << files_[i]->path << "</" << XML_FILE << ">" << endl;
}
cout << "</" << XML_ROOT << ">" << endl;
} public: virtual void characters( const ACEXML_Char *ch, size_t start, size_t length )
{
if(flag_ == FLAG_FILE)
{
files_[files_.size() - 1]->path = ch;
}
flag_ = FLAG_NULL;
} virtual void endDocument( void )
{
} virtual void endElement( const ACEXML_Char *namespaceURI, const ACEXML_Char *localName, const ACEXML_Char *qName )
{ } virtual void endPrefixMapping( const ACEXML_Char *prefix )
{
} virtual void ignorableWhitespace( const ACEXML_Char *ch, int start, int length )
{
} virtual void processingInstruction( const ACEXML_Char *target, const ACEXML_Char *data )
{
} virtual void setDocumentLocator( ACEXML_Locator *locator )
{
locator_ = locator;
} virtual void skippedEntity( const ACEXML_Char *name )
{
} virtual void startDocument( void )
{
} virtual void startElement( const ACEXML_Char *namespaceURI, const ACEXML_Char *localName, const ACEXML_Char *qName, ACEXML_Attributes *atts )
{
//file节点
if(stricmp(localName, XML_FILE) == 0)
{
if(root_.count == files_.size())
{
return;
}
flag_ = FLAG_FILE;
ROOT_FILE* file = new ROOT_FILE();
files_.push_back(file);
for(int i=0; i<atts->getLength(); ++i)
{
const char* qname = atts->getQName(i);
if(stricmp(qname, XML_ID) == 0)
{
file->id = atoi(atts->getValue(i));
}
}
}
//root节点
else if(stricmp(localName, XML_ROOT) == 0)
{
flag_ = FLAG_ROOT;
for(int i=0; i<atts->getLength(); ++i)
{
const char* qname = atts->getQName(i);
if(stricmp(qname, XML_VER) == 0)
{
root_.version= atoi(atts->getValue(i));
}
else if(stricmp(qname, XML_COUNT) == 0)
{
root_.count = atoi(atts->getValue(i));
}
}
} } virtual void startPrefixMapping( const ACEXML_Char *prefix, const ACEXML_Char *uri )
{
} virtual void notationDecl( const ACEXML_Char *name, const ACEXML_Char *publicId, const ACEXML_Char *systemId )
{
} virtual void unparsedEntityDecl( const ACEXML_Char *name, const ACEXML_Char *publicId, const ACEXML_Char *systemId, const ACEXML_Char *notationName )
{ } virtual ACEXML_InputSource * resolveEntity( const ACEXML_Char *publicId, const ACEXML_Char *systemId )
{
return 0;
} virtual void error( ACEXML_SAXParseException &exception )
{
} virtual void fatalError( ACEXML_SAXParseException &exception )
{
} virtual void warning( ACEXML_SAXParseException &exception )
{
} private:
//xml文件路径
string filepath_;
ACEXML_Locator* locator_;
ROOT root_;
vector<ROOT_FILE*> files_;
enum FLAG
{
FLAG_NULL,
FLAG_ROOT,
FLAG_FILE,
};
int flag_;
};
xml_parser完整代码展示
#include "ACEXML/common/FileCharStream.h"
#include "ACEXML/parser/parser/Parser.h" //对xml文件进行解析的类，将解析后的数据保存的格式依赖于HANDLER类
//HANDLER 必须继承自ACEXML_DefaultHandler类，并且提供"string path();"这样的方法
//注意：此对象不提供多进程或多线程按序访问的功能
template< typename HANDLER>
class xml_parser
{
public:
static bool parse(HANDLER& handler)
{
ACEXML_FileCharStream* fstm = new(std::nothrow)ACEXML_FileCharStream();
if(!fstm)
{
return false;
}
string path = handler.path();
if(path.empty())
{
return false;
}
fstm->open(path.c_str());
//ACEXML_InputSource类的析构方法中会通过“delete fstm”来释放内存
ACEXML_InputSource input(fstm);
ACEXML_Parser parser;
parser.setContentHandler(&handler);
parser.setDTDHandler(&handler);
parser.setEntityResolver(&handler);
parser.setErrorHandler(&handler);
try
{
parser.parse(&input);
}
catch(const ACEXML_Exception* ex)
{
ex->print();
return false;
}
catch(std::bad_alloc& ex)
{
return false;
}
return true;
}
};
调用代码展示
#include "xml_handler.h"
#include "xml_parser.h" int main(int argc, char* argv[])
{
xml_handler handler("D:\\test.xml");
xml_parser<xml_handler>::parse(handler);
cout << "root version:" << handler.root().version << ", count:" << handler.root().count << endl;
cout << "---------------------" << endl;
for(size_t i=0; i<handler.count(); ++i)
{
cout << "file id:" << handler[i]->id << ", path:" << handler[i]->path << endl;
}
return 0;
};