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使用 RapidXML 实现 C++ 中的 XML 文件读取与生成,特别适合需要快速处理 XML 的场景

news 2025/10/27 6:45:18

使用 RapidXML 实现 C++ 中的 XML 文件读取与生成

RapidXML 是一个轻量级、高性能的 C++ XML 解析器，特别适合需要快速处理 XML 的场景。下面我将展示如何使用 RapidXML 进行 XML 文件的读取和生成。

1. 准备工作

首先需要下载 RapidXML 头文件，它只有头文件，无需编译。

cpp

// 下载 rapidxml.hpp 并包含在项目中
#include "rapidxml.hpp"
#include "rapidxml_utils.hpp"
#include "rapidxml_print.hpp"
#include <iostream>
#include <fstream>
#include <vector>
#include <string>

2. 读取 XML 文件

cpp

// 定义数据结构来存储解析的 XML 内容
struct Person {std::string name;int age;std::string email;
};class XMLReader {
public:// 解析 XML 文件static std::vector<Person> parsePeople(const std::string& filename) {std::vector<Person> people;try {// 读取文件内容rapidxml::file<> xmlFile(filename.c_str());rapidxml::xml_document<> doc;// 解析 XMLdoc.parse<0>(xmlFile.data());// 获取根节点rapidxml::xml_node<>* root = doc.first_node("people");if (!root) {std::cerr << "根节点 'people' 未找到!" << std::endl;return people;}// 遍历所有 person 节点for (rapidxml::xml_node<>* personNode = root->first_node("person");personNode; personNode = personNode->next_sibling()) {Person person;// 读取属性rapidxml::xml_attribute<>* idAttr = personNode->first_attribute("id");if (idAttr) {std::cout << "处理 ID: " << idAttr->value() << std::endl;
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rd.xjyl.gov.cn/upload/1982074955838750720.html}// 读取子节点for (rapidxml::xml_node<>* child = personNode->first_node();child; child = child->next_sibling()) {std::string nodeName = child->name();std::string nodeValue = child->value();if (nodeName == "name") {person.name = nodeValue;} else if (nodeName == "age") {person.age = std::stoi(nodeValue);} else if (nodeName == "email") {person.email = nodeValue;}}people.push_back(person);}} catch (const std::exception& e) {std::cerr << "解析 XML 时出错: " << e.what() << std::endl;}return people;}// 打印解析结果static void printPeople(const std::vector<Person>& people) {for (const auto& person : people) {std::cout << "姓名: " << person.name << ", 年龄: " << person.age << ", 邮箱: " << person.email << std::endl;}}
};

3. 生成 XML 文件

cpp

class XMLWriter {
public:// 创建 XML 文档static void createPeopleXML(const std::vector<Person>& people, const std::string& filename) {rapidxml::xml_document<> doc;// 创建 XML 声明rapidxml::xml_node<>* decl = doc.allocate_node(rapidxml::node_declaration);decl->append_attribute(doc.allocate_attribute("version", "1.0"));decl->append_attribute(doc.allocate_attribute("encoding", "UTF-8"));doc.append_node(decl);// 创建根节点rapidxml::xml_node<>* root = doc.allocate_node(rapidxml::node_element, "people");doc.append_node(root);int id = 1;for (const auto& person : people) {// 创建 person 节点rapidxml::xml_node<>* personNode = doc.allocate_node(rapidxml::node_element, "person");// 添加 id 属性char* idStr = doc.allocate_string(std::to_string(id++).c_str());personNode->append_attribute(doc.allocate_attribute("id", idStr));// 创建子节点addChildNode(doc, personNode, "name", person.name);char* ageStr = doc.allocate_string(std::to_string(person.age).c_str());addChildNode(doc, personNode, "age", ageStr);addChildNode(doc, personNode, "email", person.email);root->append_node(personNode);}// 保存到文件saveToFile(doc, filename);}private:// 添加子节点辅助函数static void addChildNode(rapidxml::xml_document<>& doc, rapidxml::xml_node<>* parent, const std::string& name, const std::string& value) {char* nodeName = doc.allocate_string(name.c_str());char* nodeValue = doc.allocate_string(value.c_str());rapidxml::xml_node<>* child = doc.allocate_node(rapidxml::node_element, nodeName, nodeValue);parent->append_node(child);}// 保存文件辅助函数static void saveToFile(rapidxml::xml_document<>& doc, const std::string& filename) {std::ofstream file(filename);if (!file.is_open()) {std::cerr << "无法创建文件: " << filename << std::endl;return;}file << doc;file.close();std::cout << "XML 文件已保存: " << filename << std::endl;}
};

4. 完整示例

cpp

#include <iostream>
#include <vector>
#include <string>// 假设已经包含了 RapidXML 头文件int main() {// 示例数据std::vector<Person> people = {{"张三", 25, "zhangsan@example.com"},{"李四", 30, "lisi@example.com"},{"王五", 28, "wangwu@example.com"}};// 生成 XML 文件std::string outputFile = "people.xml";XMLWriter::createPeopleXML(people, outputFile);// 读取并解析 XML 文件std::vector<Person> parsedPeople = XMLReader::parsePeople(outputFile);// 打印解析结果std::cout << "\n解析结果:" << std::endl;XMLReader::printPeople(parsedPeople);return 0;
}

5. 示例 XML 文件

生成的 people.xml 文件内容如下：

xml

<?xml version="1.0" encoding="UTF-8"?>
<people><person id="1"><name>张三</name><age>25</age><email>zhangsan@example.com</email></person><person id="2"><name>李四</name><age>30</age><email>lisi@example.com</email></person><person id="3"><name>王五</name><age>28</age><email>wangwu@example.com</email></person>
</people>

6. 关键要点

内存管理: RapidXML 使用原地解析，不复制字符串数据，因此源数据必须保持有效
性能: RapidXML 是性能最优的 XML 解析器之一
简单性: API 设计简洁，学习曲线平缓
局限性: 不支持 DTD 验证和 XPath

7. 错误处理增强版

cpp

class SafeXMLParser {
public:static std::vector<Person> safeParse(const std::string& filename) {std::vector<Person> people;try {rapidxml::file<> xmlFile(filename.c_str());rapidxml::xml_document<> doc;doc.parse<0>(xmlFile.data());rapidxml::xml_node<>* root = doc.first_node("people");if (!root) {throw std::runtime_error("缺少根节点 'people'");}for (rapidxml::xml_node<>* personNode = root->first_node("person");personNode; personNode = personNode->next_sibling()) {Person person;bool hasName = false;bool hasAge = false;for (rapidxml::xml_node<>* child = personNode->first_node();child; child = child->next_sibling()) {std::string nodeName = child->name();std::string nodeValue = child->value();if (nodeName == "name") {person.name = nodeValue;hasName = true;} else if (nodeName == "age") {try {person.age = std::stoi(nodeValue);hasAge = true;} catch (const std::exception&) {std::cerr << "警告: 无效的年龄值: " << nodeValue << std::endl;
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};

这个完整的示例展示了如何使用 RapidXML 进行 XML 文件的读取和生成，包括错误处理、内存管理和数据结构的封装。

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