RapidXml用法[通俗易懂]

大家好，又见面了，我是你们的朋友全栈君。

一、写xml 文件

#include <iostream>
#include "rapidxml/rapidxml.hpp"
#include "rapidxml/rapidxml_utils.hpp"
#include "rapidxml/rapidxml_print.hpp"

using namespace rapidxml;

int main()
{    
    xml_document<> doc;  
    xml_node<>* rot = doc.allocate_node(rapidxml::node_pi,doc.allocate_string("xml version='1.0' encoding='utf-8'"));
    doc.append_node(rot);
    xml_node<>* node =   doc.allocate_node(node_element,"config","information");  
    xml_node<>* color =   doc.allocate_node(node_element,"color",NULL);  
    doc.append_node(node);
    node->append_node(color);
    color->append_node(doc.allocate_node(node_element,"red","0.1"));
    color->append_node(doc.allocate_node(node_element,"green","0.1"));
    color->append_node(doc.allocate_node(node_element,"blue","0.1"));
    color->append_node(doc.allocate_node(node_element,"alpha","1.0"));

    xml_node<>* size =   doc.allocate_node(node_element,"size",NULL); 
    size->append_node(doc.allocate_node(node_element,"x","640"));
    size->append_node(doc.allocate_node(node_element,"y","480"));
    node->append_node(size);

    xml_node<>* mode = doc.allocate_node(rapidxml::node_element,"mode","screen mode");
    mode->append_attribute(doc.allocate_attribute("fullscreen","false"));
    node->append_node(mode);

    std::string text;  
    rapidxml::print(std::back_inserter(text), doc, 0);  

    std::cout<<text<<std::endl; 

    std::ofstream out("config.xml");
    out << doc;

    system("PAUSE");
    return EXIT_SUCCESS;
}

生成的xml例如以下：

<?xml version="1.0" encoding="utf-8" ?> 
 <config>
  <color>
      <red>0.1</red> 
      <green>0.1</green> 
      <blue>0.1</blue> 
      <alpha>1.0</alpha> 
  </color>
  <size>
      <x>640</x> 
      <y>480</y> 
  </size>
  <mode fullscreen="false">screen mode</mode> 
 </config>

写文件样例2：

#include <string>
#include <iostream>
#include <fstream>
#include "rapidxml/rapidxml.hpp"
#include "rapidxml/rapidxml_utils.hpp"
#include "rapidxml/rapidxml_print.hpp"


using namespace rapidxml;
using namespace std;

int main(int argc, char* argv[])
{

    xml_document<> doc; //是解析器
    char a[] = "<top>"//假设单独传, 就不能加上xml的头部信息，
               //否则会报错
               "<name>tangqiang</name>"
               "<age>22</age>"
               "</top>";
    char* p = a;
    doc.parse<0>(p);

    xml_node<>* node = doc.first_node();//去顶级结点
    cout << (node->name())<< endl;
    node = node->first_node();
    while (node) {
        cout << node->name() << node->value() << endl;//name() value()返回的字符串不会去掉首尾的空白字符
        node = node->next_sibling();
    }

    ofstream out("test.xml");//ofstream 默认时，假设文件存在则会覆盖原来的内容，不存在则会新建
    out << doc;//doc 这样输出时在目标文件里不会有xml 头信息---<?xml version='1.0' encoding='utf-8' >
    out.close();
    system("pause");
    return 0;
}

生成的xml例如以下：

<top>
    <name>tangqiang</name>
    <age>22</age>
</top>

二、读取xml文件

#include <iostream>
#include "rapidxml/rapidxml.hpp"
#include "rapidxml/rapidxml_utils.hpp"
#include "rapidxml/rapidxml_print.hpp"

using namespace rapidxml;

int main()
{
    file<> fdoc("config.xml");
    std::cout<<fdoc.data()<<std::endl;
    xml_document<>   doc;
    doc.parse<0>(fdoc.data());

    std::cout<<doc.name()<<std::endl;

    //! 获取根节点
    xml_node<>* root = doc.first_node();
    std::cout<<root->name()<<std::endl;

    //! 获取根节点第一个节点
    xml_node<>* node1 = root->first_node();
    std::cout<<node1->name()<<std::endl;

    xml_node<>* node11 = node1->first_node();
    std::cout<<node11->name()<<std::endl;
    std::cout<<node11->value()<<std::endl;

    //! 加入之后再次保存
    //须要说明的是rapidxml明显有一个bug
//那就是append_node(doc.allocate_node(node_element,"h","0"));的时候并不考虑该对象是否存在!
    xml_node<>* size = root->first_node("size");
    size->append_node(doc.allocate_node(node_element,"w","0"));
    size->append_node(doc.allocate_node(node_element,"h","0"));

    std::string text;
    rapidxml::print(std::back_inserter(text),doc,0);

    std::cout<<text<<std::endl;

    std::ofstream out("config.xml");
    out << doc;

    system("PAUSE");
    return EXIT_SUCCESS;
}

生成的xml为：

<config>
    <color>
        <red>0.1</red>
        <green>0.1</green>
        <blue>0.1</blue>
        <alpha>1.0</alpha>
    </color>
    <size>
        <x>640</x>
        <y>480</y>
        <w>0</w>
        <h>0</h>
    </size>
    <mode fullscreen="false">screen mode</mode>
</config>

三、删除节点

#include "rapidxml/rapidxml.hpp"
#include "rapidxml/rapidxml_utils.hpp"
#include "rapidxml/rapidxml_print.hpp"

#include<iostream>
using namespace rapidxml;

int main()
{
    file<> fdoc("config.xml");
    xml_document<> doc;
    doc.parse<0>(fdoc.data());

    std::string text;  
    rapidxml::print(std::back_inserter(text), doc, 0);  
    std::cout<<text<<std::endl; 

    xml_node<>* root = doc.first_node();

    xml_node<>* sec = root->first_node();

    root->remove_node(sec); //移除根节点下的sec结点(包含该结点下全部结点)
    text="删除一个节点\r\n";  
    rapidxml::print(std::back_inserter(text), doc, 0);  
    std::cout<<text<<std::endl; 

    root->remove_all_nodes(); //移除根节点下全部结点
    text="删除全部节点\r\n";  
    rapidxml::print(std::back_inserter(text), doc, 0);  
    std::cout<<text<<std::endl; 

    std::ofstream out("test.xml");
    out<<doc;
    system("pause");
    return 0;
}

输出信息例如以下：

<config>
    <color>
        <red>0.1</red>
        <green>0.1</green>
        <blue>0.1</blue>
        <alpha>1.0</alpha>
    </color>
    <size>
        <x>640</x>
        <y>480</y>
        <w>0</w>
        <h>0</h>
    </size>
    <mode fullscreen="false">screen mode</mode>
</config>


删除一个节点

<config>
    <size>
        <x>640</x>
        <y>480</y>
        <w>0</w>
        <h>0</h>
    </size>
    <mode fullscreen="false">screen mode</mode>
</config>


删除全部节点

<config/>

四、编辑节点信息

临时找到的编辑方法就是先删除再添加

#include "rapidxml/rapidxml.hpp"
#include "rapidxml/rapidxml_utils.hpp"
#include "rapidxml/rapidxml_print.hpp"

#include<iostream>
using namespace rapidxml;

int main()
{
    file<> fdoc("config.xml");
    std::cout<<fdoc.data()<<std::endl;
    xml_document<> doc;
    doc.parse<0>(fdoc.data());

    std::cout<<doc.name()<<std::endl;

    //! 获取根节点
    xml_node<>* root = doc.first_node();
    xml_node<>* delnode = root->first_node("color");
    root->remove_node(delnode);//先删除address节点
    //
    xml_node<>* lnode = root->first_node("size");//找到post节点
    xml_node<>* mynode=doc.allocate_node(node_element,"address","河北");
    root->insert_node(lnode,mynode);

    std::string text;
    rapidxml::print(std::back_inserter(text),doc,0);


    std::cout<<text<<std::endl;

    std::ofstream out("version.xml");
    out << doc;
    system("pause");
    return 0;   
}

输出例如以下：
<config>
    <color>
        <red>0.1</red>
        <green>0.1</green>
        <blue>0.1</blue>
        <alpha>1.0</alpha>
    </color>
    <size>
        <x>640</x>
        <y>480</y>
        <w>0</w>
        <h>0</h>
    </size>
    <mode fullscreen="false">screen mode</mode>
</config>


<config>
    <address>河北</address>
    <size>
        <x>640</x>
        <y>480</y>
        <w>0</w>
        <h>0</h>
    </size>
    <mode fullscreen="false">screen mode</mode>
</config>

五、遍历全部节点

for(rapidxml::xml_node<char> * node = parent_node->first_node("node name");
    node != NULL;
    node = node->next_sibling())
{
    //TO DO
}

六、遍历全部属性

for(rapidxml::xml_attribute<char> * attr = node->first_attribute("node name");
    attr != NULL;
    attr = attr->next_attribute())
{
    char * value = attr->value();
}