（4）rapidxml的详解及使⽤
RapidXml是指 XML DOM解析⼯具包，是⼀个快速的读写xml⽂件的库⽂件（hpp）。
（1）创建XML⽂件
#include <iostream>
#include <string>
#include <fstream>
#include "string.h"
#include "rapidxml.hpp"
#include "rapidxml_print.hpp"
#include "rapidxml_utils.hpp"
static const int buf_len = 2048;
static char buf[buf_len] = { 0 };
void createXML(const char * file_name)
{
// 1.DOM
rapidxml::xml_document<> doc;
// 2.node_declaration
rapidxml::xml_node<>* declaration = doc.allocate_node(rapidxml::node_declaration);
declaration->append_attribute(doc.allocate_attribute("version", "1.0"));
declaration->append_attribute(doc.allocate_attribute("encoding", "utf-8"));
doc.append_node(declaration);
// 3.node_pi
rapidxml::xml_node<>* dec = doc.allocate_node(rapidxml::node_pi,doc.allocate_string("xml version=\"1.0\" encoding=\"utf-8\"")); doc.append_node(dec);
// 4.node_element
rapidxml::xml_node<>* root = doc.allocate_node(rapidxml::node_element, "root");
doc.append_node(root);
// 5.node_comment
rapidxml::xml_node<>* comment = doc.allocate_node(rapidxml::node_comment, 0, "这是⼀个注释节点");
root->append_node(comment);
rapidxml::xml_node<>* students = doc.allocate_node(rapidxml::node_element, "students");
// 6.node_data
rapidxml::xml_node<>* one_student = doc.allocate_node(rapidxml::node_element, "student");
rapidxml::xml_node<>* name = doc.allocate_node(rapidxml::node_data,"node_name","11");
one_student->append_node(name);
students->append_node(one_student);
// 7.node_element with value
rapidxml::xml_node<>* two_student = doc.allocate_node(rapidxml::node_element, "student","22");
students->append_node(two_student);
// 8.set attribute
rapidxml::xml_node<>* three_student = doc.allocate_node(rapidxml::node_element,"student","33");
students->append_node(three_student);
three_student->append_attribute(doc.allocate_attribute("course", doc.allocate_string(buf)));
three_student->append_attribute(doc.allocate_attribute("score","98"));
/
/ 9.node_element without value
rapidxml::xml_node<>* four_student = doc.allocate_node(rapidxml::node_element,"student");
students->append_node(four_student);
// 10.node_cdata
rapidxml::xml_node<>* five_student = doc.allocate_node(rapidxml::node_cdata,"student","55");
students->append_node(five_student);
// 11.node_cdata
rapidxml::xml_node<>* six_student = doc.allocate_node(rapidxml::node_pi,"student","66");
students->append_node(six_student);
// 12.node_cdata
rapidxml::xml_node<>* seven_student = doc.allocate_node(rapidxml::node_doctype,"student","77");
students->append_node(seven_student);
root->append_node(students);
// 13.输出DOM到命令⾏
std::cout<<doc;
// 14.输出DOM到⽂件
std::ofstream outfile(file_name, std::ios::out);
if (outfile)
{
char *end = rapidxml::print(buf, doc, 0);
*end = 0;
outfile << buf;
outfile.close();
}
}
int main()
{
const char *file_name = "l";
createXML(file_name);
return0;
}
<?xml version="1.0" encoding="utf-8"?>
<?xml version="1.0" encoding="utf-8" ?>
<root>
<!--这是⼀个注释节点-->
<students>
<student>11</student>
<student>22</student>
<student course="" score="98">33</student>
<student/>
<![CDATA[55]]>
<?student 66?>
<!DOCTYPE 77>
</students>
parse error怎么解决</root>
（2）读取XML⽂件
//rapidxml_utils.hpp
file类
data() 返回char* 的xml⽂本内容
size() 返回 unsigned int的⽂本数据长度
定义：rapidxml::file<0> valName(“filepath”);
//rapidxml.hpp
xml_document类
parse(Ch *text)；将⽂本数据解析为DOM tree
clear()；清空DOM tree
定义：rapidxml::xml_document<0> doc;
const int parse_default = 0;
const int parse_full = parse_declaration_node | parse_comment_nodes | parse_doctype_node | parse_pi_nodes | parse_validate_closing_tags #include <iostream>
#include <string>
#include <fstream>
#include "unistd.h"
#include "string.h"
#include "rapidxml.hpp"
#include "rapidxml_print.hpp"
#include "rapidxml_utils.hpp"
static const int buf_len = 2048;
static char buf[buf_len] = { 0 };
//利⽤rapidxml::file读取配置⽂件
void readXMLByFile(const char *file_name)
{
try
{
// 1.清空缓冲区
memset(buf,0,buf_len);
// 2.拼接绝对路径
std::string strXml = "/home/sunjimeng/test/";
strXml.append(file_name);
/
/ 3.⽤file⽂件读⼊缓冲区
rapidxml::file<> fdoc(strXml.c_str());
// 4.打印从⽂件中读取的内容
std::cout<<fdoc.data();
// 5.解析获取DOM实例
rapidxml::xml_document<> doc;
doc.parse<0>(fdoc.data());
}catch(rapidxml::parse_error e)
{
std::cout<<e.what()<<std::endl;
return;
}
}
void readXMLByStream(const char *file_name)
{
try
{
// 1.清空缓冲区
memset(buf,0,buf_len);
// 2.判断⽂件是否存在
if(access(file_name,F_OK) == -1)
std::cout<<"xml file "<<file_name<<"is not exits!"<<std::endl;
/
/ 3.实例化⽂件读取流
std::ifstream infile(file_name, std::ios::in);
if(!infile)
{
std::cout<<"file stream instance error!"<<std::endl;
return;
}
// 4.读取⽂件内容到缓冲区
// 5.输出⽂件内容
std::cout<<buf<<std::endl;
/
/ 6.实例化DOM
rapidxml::xml_document<> doc;
doc.parse<0>(buf);
}catch(rapidxml::parse_error e)
{
std::cout<<e.what()<<std::endl;
return;
}
}
int main()
{
const char *file_name = "l";
readXMLByFile(file_name);
readXMLByStream(file_name);
return0;
}
（3）修改及删除（接着上⽂）
//rapidxml.hpp
xml_node类
1）node_type type() const; 获取结点类型获取的类型是枚举的
2）Ch* name() const; 获取结点名
3）std::size_t name_size() const; 获取结点名长度
4）Ch* value() const; 获取结点值
5）std::size_t value_size() const; 获取结点值长度
6）xml_node* first_node(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; 获取DOM Tree第⼀个⼦结点的指针第⼀个参数为节点名，如果给定第⼀个参数为”a”，则该函数寻结点名为a的第⼀个⼦结点；第⼆个参数为结点名长度
7）xml_node* last_node(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; 获取DOM Tree最后⼀个⼦结点的指针
参数含义同上
8)xml_attribute* first_attribute(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; 获取结点的第⼀个属性指针
9）xml_attribute* next_attribute(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; 获取结点的下⼀个属性指针10）xml_attribute* last_attribute(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const；获取结点的最后⼀个属性指针11）xml_node* previous_sibling(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=tr
ue) const；获取上⼀个同级结点的指针12）xml_node* next_sibling(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; 获取下⼀个同级结点的指针
13）xml_attribute* first_attribute(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; 获取第⼀个同级结点的指针14）xml_attribute* last_attribute(const Ch *name=0, std::size_t name_size=0, bool case_sensitive=true) const; 获取最后⼀个同级结点的指针15）void insert_node(xml_node< Ch > *where, xml_node< Ch > *child)；在第⼀个参数指向的结点之前，插⼊⼀个结点
xml_attribute类
1)xml_attribute *previous_attribute(const Ch *name = 0, std::size_t name_size = 0, bool case_sensitive = true) const；获取前⼀个属性
2）xml_attribute *next_attribute(const Ch *name = 0, std::size_t name_size = 0, bool case_sensitive = true) const；获取后⼀个属性
#include <iostream>
#include <string>
#include <fstream>
#include "unistd.h"
#include "string.h"
#include "rapidxml.hpp"
#include "rapidxml_print.hpp"
#include "rapidxml_utils.hpp"
static const int buf_len = 2048;
static char buf[buf_len] = { 0 };
void parseXML(const char * file_name)
{
memset(buf,0,buf_len);
try
{
std::ifstream infile(file_name, std::ios::in);
if (!infile)
{
return;
}
std::cout << buf << std::endl;
rapidxml::xml_document<> doc;
doc.parse<0>(buf);
/
/ 取得根节点
rapidxml::xml_node<> *root = doc.first_node("root");
// 遍历students的⼦节点
int flag = 0;
for (rapidxml::xml_node<> * node = root->first_node("students")->first_node(); node; node = node->next_sibling()) {
if(node->first_node() != NULL)
std::cout<<"name :"<<node->name()<<" value : "<<node->value()<<std::endl;
else
std::cout<<"name :"<<node->name()<<" has no value!"<<std::endl;
for(rapidxml::xml_attribute<> * attribute = node->first_attribute(); attribute; attribute = attribute->next_attribute())
std::cout<<" attribute name = "<<attribute->name()<<" attribute value = "<<attribute->value()<<std::endl;
}
} catch(rapidxml::parse_error e)
{
std::cout<<e.what()<<std::endl;
}
}
void modifyXML(const char * file_name)
{
memset(buf,0,buf_len);
//⽤file解析DOM时必须是绝对路径
std::string strXml = "/home/sunjimeng/test/";
strXml.append(file_name);
rapidxml::file<> fdoc(strXml.c_str());
//打印读取的⽂件
//std::cout<<fdoc.data();
rapidxml::xml_document<> doc;
doc.parse<0>(fdoc.data());
//取得根节点
rapidxml::xml_node<> *root = doc.first_node("root");
rapidxml::xml_node<> *students = root->first_node("students");
if(students != NULL)
std::cout<<"student is not null"<<std::endl;
else
return;
//删除最后⼀个元素
if(students->last_node() != NULL)
students->remove_last_node();
//删除第⼀个元素
if(students->first_node() != NULL)
students->remove_first_node();
rapidxml::xml_node<> *ptrNode = students->first_node(); int size = 0;
while(ptrNode)
{
size++;
//删除所有属性
ptrNode->remove_all_attributes();
ptrNode = ptrNode->next_sibling();
}
std::cout<<"size = "<<size<<std::endl;
std::string text;
rapidxml::print(std::back_inserter(text),doc,0);
std::cout<<text<<std::endl;
std::ofstream out(file_name);
out<<doc;
}
int main()
{
const char *file_name = "l";
modifyXML(file_name);
parseXML(file_name);
return0;
}
student is not null
size = 1
<root>
<students>
<student>33</student>
</students>
</root>
<root>
<students>
<student>33</student>
</students>
</root>
name :student value : 33
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