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。