C++的RapidJSON库的分析和实践

#include <iostream>
#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
int main() {
    // 解析JSON数据
    const char* json = "{\"name\":\"John\",\"age\":30}";
    rapidjson::Document document;
    document.Parse(json);
    
    // 修改属性值
    rapidjson::Value& name = document["name"];
    name.SetString("David");
    rapidjson::Value& age = document["age"];
    age.SetInt(35);
    
    // 生成JSON数据
    rapidjson::StringBuffer buffer;
    rapidjson::Writer<rapidjson::StringBuffer> writer(buffer);
    document.Accept(writer);
    
    // 输出结果
    std::cout << buffer.GetString() << std::endl;
    
    return 0;
}

#include <iostream>
#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
#include "rapidjson/filereadstream.h"
#include "rapidjson/filewritestream.h"
// 解析JSON文件并打印其中的数据
void parseJSONFile(const char* filename) {
  FILE* file = fopen(filename, "r");
  if (file == nullptr) {
    std::cerr << "Failed to open file: " << filename << std::endl;
    return;
  }
  
  char readBuffer[65536];
  rapidjson::FileReadStream inputStream(file, readBuffer, sizeof(readBuffer));
  
  rapidjson::Document document;
  document.ParseStream(inputStream);
  
  if (document.HasParseError()) {
    std::cerr << "Failed to parse JSON file: " << filename << std::endl;
    fclose(file);
    return;
  }
  
  // 从JSON中获取数据
  const rapidjson::Value& name = document["name"];
  const rapidjson::Value& age = document["age"];
  
  if (name.IsString() && age.IsInt()) {
    std::cout << "Name: " << name.GetString() << std::endl;
    std::cout << "Age: " << age.GetInt() << std::endl;
  } else {
    std::cerr << "Invalid JSON format in file: " << filename << std::endl;
  }
  
  fclose(file);
}
// 生成JSON数据并保存到文件
void generateJSONFile(const char* filename) {
  rapidjson::Document document;
  document.SetObject();
  
  rapidjson::Value name;
  name.SetString("John");
  document.AddMember("name", name, document.GetAllocator());
  
  rapidjson::Value age;
  age.SetInt(30);
  document.AddMember("age", age, document.GetAllocator());
  
  FILE* file = fopen(filename, "w");
  if (file == nullptr) {
    std::cerr << "Failed to create file: " << filename << std::endl;
    return;
  }
  
  char writeBuffer[65536];
  rapidjson::FileWriteStream outputStream(file, writeBuffer, sizeof(writeBuffer));
  
  rapidjson::Writer<rapidjson::FileWriteStream> writer(outputStream);
  document.Accept(writer);
  
  fclose(file);
}
int main() {
  // 解析JSON文件并打印数据
  const char* jsonFilename = "data.json";
  parseJSONFile(jsonFilename);
  
  // 生成JSON数据并保存到文件
  const char* outputFilename = "output.json";
  generateJSONFile(outputFilename);
  
  return 0;
}

#include "rapidjson/document.h"
#include "rapidjson/istreamwrapper.h"
using namespace rapidjson;
int main() {
    std::ifstream ifs("data.json");
    IStreamWrapper isw(ifs);
    Document document;
    document.ParseStream(isw);
    if (document.HasParseError()) {
        printf("JSON parse error: %s", GetParseError_En(document.GetParseError()));
        return 1;
    }
    // 从document中提取数据
    if (document.HasMember("name") && document["name"].IsString()) {
        std::string name = document["name"].GetString();
        // 使用name进行后续操作
        // ...
    }
    return 0;
}

#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
using namespace rapidjson;
int main() {
    // 创建一个空的Document对象，用于生成JSON
    Document document;
    document.SetObject();
    // 添加键值对到Document中
    Value obj(kObjectType);
    obj.AddMember("name", "John", document.GetAllocator());
    obj.AddMember("age", 30, document.GetAllocator());
    document.AddMember("person", obj, document.GetAllocator());
    // 将Document转换为JSON字符串
    StringBuffer buffer;
    Writer<StringBuffer> writer(buffer);
    document.Accept(writer);
    // 输出生成的JSON字符串
    std::cout << buffer.GetString() << std::endl;
    return 0;
}

#include "rapidjson/document.h"
using namespace rapidjson;
void Traverse(const Value& value, const std::string& parentKey = "") {
    if (value.IsObject()) {
        for (Value::ConstMemberIterator itr = value.MemberBegin(); itr != value.MemberEnd(); ++itr) {
            std::string key = parentKey.empty() ? itr->name.GetString() : parentKey + "." + itr->name.GetString();
            Traverse(itr->value, key);
        }
    } else if (value.IsArray()) {
        for (SizeType i = 0; i < value.Size(); ++i) {
            std::string key = parentKey.empty() ? std::to_string(i) : parentKey + "." + std::to_string(i);
            Traverse(value[i], key);
        }
    } else {
        // 当前节点为值类型，进行处理
        std::cout << parentKey << ": " << value.GetString() << std::endl;
    }
}
int main() {
    const char* json = "{\"name\":\"John\",\"age\":30,\"languages\":[\"C++\",\"Python\",\"JavaScript\"]}";
    Document document;
    document.Parse(json);
    if (document.HasParseError()) {
        printf("JSON parse error: %s", GetParseError_En(document.GetParseError()));
        return 1;
    }
    Traverse(document);
    return 0;
}