C++有关RapidJson和Jsoncpp的基本用法

一. Jsoncpp使用

1.1 Jsoncpp封装

引入头文件：

#include

示例代码：

int main()
{Json::Value JsonRoot;Json::FastWriter styleWrite;string typenum = "111";JsonRoot["TypeNum"] = typenum;JsonRoot["NAME"] = "zhangsan";Json::Value tempJson;tempJson["SEX"] = "male";tempJson["AGE"] = 18;string info = styleWrite.write(tempJson);JsonRoot["INFO"] = info;tempJson.clear();Json::Value arrJson;arrJson["CLASS"] = 001;arrJson["TEACHER"] = "Miss Li";JsonRoot["Array"].append(arrJson);string data = styleWrite.write(JsonRoot);cout << data << endl;cout << JsonRoot.toStyledString() << endl;JsonRoot.clear();return 0;
}

输出如下：

1.2 Jsoncpp解析

//解析Json::Value root;Json::Reader reader;if (reader.parse(data, root)){cout << root["INFO"].asString();//name 、typenum同理,略if (root["Array"].isArray()){for (size_t i = 0; i < root["Array"].size(); i++){cout << root["Array"][i]["CLASS"].asInt() << endl;cout << root["Array"][i]["TEACHER"].asString() << endl;}}}

额外的话： 附上一个jsoncpp序列化及反序列化博客：C++解析Json

二. RapidJson使用

2.1 基本操作：序列化

添加头文件：

#include "rapidjson/stringbuffer.h"
#include "rapidjson/writer.h"
#include "rapidjson/prettywriter.h"
#include "rapidjson/istreamwrapper.h"

string Serialize_1()
{rapidjson::StringBuffer strBuf;rapidjson::Writer<rapidjson::StringBuffer> writer(strBuf);writer.StartObject();int count = 0;  //循环写入100次while (count < 2000){count++;//1. 整数类型writer.Key("Int");writer.Int(1);//2. 浮点类型writer.Key("Double");writer.Double(12.0000001);//3. 字符串类型writer.Key("String");writer.String("This is a string");//4. 结构体类型writer.Key("Object");writer.StartObject();writer.Key("name");writer.String("qq849635649");writer.Key("age");writer.Int(25);writer.EndObject();//5. 数组类型//5.1 整型数组writer.Key("IntArray");writer.StartArray();//顺序写入即可writer.Int(10);writer.Int(20);writer.Int(30);writer.EndArray();//5.2 浮点型数组writer.Key("DoubleArray");writer.StartArray();for (int i = 1; i < 4; i++){writer.Double(i * 1.0);}writer.EndArray();//5.3 字符串数组writer.Key("StringArray");writer.StartArray();writer.String("one");writer.String("two");writer.String("three");writer.EndArray();//5.4 混合型数组//这说明了，一个json数组内容是不限制类型的writer.Key("MixedArray");writer.StartArray();writer.String("one");writer.Int(50);writer.Bool(false);writer.Double(12.005);writer.EndArray();//5.5 结构体数组writer.Key("People");writer.StartArray();for (int i = 0; i < 3; i++){writer.StartObject();writer.Key("name");writer.String("qq849635649");writer.Key("age");writer.Int(i * 10);writer.Key("sex");writer.Bool((i % 2) == 0);writer.EndObject();}writer.EndArray();}writer.EndObject();string data = strBuf.GetString();return data;
}

2.2 反序列化

添加头文件：

#include "rapidjson/document.h"

void deSerialize_l()
{string data ="{\"Int\":1,""\"Double\":12.0000001,""\"String\":\"This is a string\",""\"Object\":{\"name\":\"qq849635649\",\"age\":25},""\"IntArray\":[10,20,30],""\"DoubleArray\":[1.0,2.0,3.0],""\"StringArray\":[\"one\",\"two\",\"three\"],""\"MixedArray\":[\"one\",50,false,12.005],""\"People\":[{\"name\":\"qq849635649\",\"age\":0,\"sex\":true},""{\"name\":\"qq849635649\",\"age\":10,\"sex\":false},""{\"name\":\"qq849635649\",\"age\":20,\"sex\":true}]}";//创建解析对象rapidjson::Document doc;//首先进行解析，没有解析错误才能进行具体字段的解析if (!doc.Parse(data.data()).HasParseError()){//1. 解析整数if (doc.HasMember("Int") && doc["Int"].IsInt()){cout << "Int = " << doc["Int"].GetInt() << endl;}//2. 解析浮点型if (doc.HasMember("Double") && doc["Double"].IsDouble()){cout << "Double = " << doc["Double"].GetDouble() << endl;}//3. 解析字符串if (doc.HasMember("String") && doc["String"].IsString()){cout << "String = " << doc["String"].GetString() << endl;}//4. 解析结构体if (doc.HasMember("Object") && doc["Object"].IsObject()){const rapidjson::Value& object = doc["Object"];if (object.HasMember("name") && object["name"].IsString()){cout << "Object.name = " << object["name"].GetString() << endl;}if (object.HasMember("age") && object["age"].IsInt()){cout << "Object.age = " << object["age"].GetInt() << endl;}}//5. 解析数组类型//5.1 整型数组类型if (doc.HasMember("IntArray") && doc["IntArray"].IsArray()){//5.1.1 将字段转换成为rapidjson::Value类型const rapidjson::Value& array = doc["IntArray"];//5.1.2 获取数组长度size_t len = array.Size();//5.1.3 根据下标遍历，注意将元素转换为相应类型，即需要调用GetInt()for (size_t i = 0; i < len; i++){cout << "IntArray[" << i << "] = " << array[i].GetInt() << endl;}}//5.2 浮点型数组类型if (doc.HasMember("DoubleArray") && doc["DoubleArray"].IsArray()){const rapidjson::Value& array = doc["DoubleArray"];size_t len = array.Size();for (size_t i = 0; i < len; i++){//为防止类型不匹配，一般会添加类型校验if (array[i].IsDouble()){cout << "DoubleArray[" << i << "] = " << array[i].GetDouble() << endl;}}}//5.3 字符串数组类型if (doc.HasMember("StringArray") && doc["StringArray"].IsArray()){const rapidjson::Value& array = doc["StringArray"];size_t len = array.Size();for (size_t i = 0; i < len; i++){//为防止类型不匹配，一般会添加类型校验if (array[i].IsString()){cout << "StringArray[" << i << "] = " << array[i].GetString() << endl;}}}//5.4 混合型if (doc.HasMember("MixedArray") && doc["MixedArray"].IsArray()){const rapidjson::Value& array = doc["MixedArray"];size_t len = array.Size();for (size_t i = 0; i < len; i++){//为防止类型不匹配，一般会添加类型校验if (array[i].IsString()){cout << "MixedArray[" << i << "] = " << array[i].GetString() << endl;}else if (array[i].IsBool()){cout << "MixedArray[" << i << "] = " << array[i].GetBool() << endl;}else if (array[i].IsInt()){cout << "MixedArray[" << i << "] = " << array[i].GetInt() << endl;}else if (array[i].IsDouble()){cout << "MixedArray[" << i << "] = " << array[i].GetDouble() << endl;}}}//5.5 结构体数组类型if (doc.HasMember("People") && doc["People"].IsArray()){const rapidjson::Value& array = doc["People"];size_t len = array.Size();for (size_t i = 0; i < len; i++){const rapidjson::Value& object = array[i];//为防止类型不匹配，一般会添加类型校验if (object.IsObject()){cout << "ObjectArray[" << i << "]: ";if (object.HasMember("name") && object["name"].IsString()){cout << "name=" << object["name"].GetString();}if (object.HasMember("age") && object["age"].IsInt()){cout << ", age=" << object["age"].GetInt();}if (object.HasMember("sex") && object["sex"].IsBool()){cout << ", sex=" << (object["sex"].GetBool() ? "男" : "女") << endl;}}}}}/***    最后注意：因为rapidjson不会做安全校验，所以要自己做安全校验，以int整型为例* “if(object.HasMember("age") && object["age"].IsInt()) {}”* 这句校验很重要，既要校验有该子段，也要校验类型正确，否则会引发程序崩溃*/
}

总结：之前有大致测试过几M的数据，jsoncpp解析大致时间10ms，而RapidJson解析时间不到它的一半。建议使用rapidjson。

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