Linux(程序设计):31---jsoncpp库（C++操作JSON）

一、jsoncpp库概述

• jsoncpp是一个c++封装的json包，跨平台支持windows、linux、unix等多系统
• jsoncpp源码地址：https://github.com/open-source-parsers/jsoncpp

库的安装

sudo apt-get install libjsoncpp-dev

• 安装完成之后，头文件默认安装在/usr/include/jsoncpp/json/目录下，库API文档默认在/usr/share/doc/libjsoncpp-dev/目录下

编译带有jsoncpp库的C++程序

• 使用如下的命令进行编译，编译时带上-ljsoncpp选项即可
• 例如：

g++ jsoncpp_demo01.c -o demo01 -ljsoncpp -std=c++11

二、jsoncpp支持的值

• jsoncpp 使用 Json::Value 对象来保存 JSON 串，Json::Value 对象可以表示如下数据类 型：

三、相关接口

检测保存的数据类型

   

    

     

      

     
     

      

       bool isNull() const;
      
     
    

     

      

     
     

      

       bool isBool() const;
      
     
    

     

      

     
     

      

       bool isInt() const;
      
     
    

     

      

     
     

      

       bool isInt64() const;
      
     
    

     

      

     
     

      

       bool isUInt() const;
      
     
    

     

      

     
     

      

       bool isUInt64() const;
      
     
    

     

      

     
     

      

       bool isIntegral() const;
      
     
    

     

      

     
     

      

       bool isDouble() const;
      
     
    

     

      

     
     

      

       bool isNumeric() const;
      
     
    

     

      

     
     

      

       bool isString() const;
      
     
    

     

      

     
     

      

       bool isArray() const;
      
     
    

     

      

     
     

      

       bool isObject() const;
      
     
   

基础数据类型的访问

   

    

     

      

     
     

      

       const char* asCString() const;
      
     
    

     

      

     
     

      

       JSONCPP_STRING asString() const;
      
     
    

     

      

     
     

      

       Int asInt() const;
      
     
    

     

      

     
     

      

       UInt asUInt() const;
      
     
    

     

      

     
     

      

       Int64 asInt64() const;
      
     
    

     

      

     
     

      

       UInt64 asUInt64() const;
      
     
    

     

      

     
     

      

       LargestInt asLargestInt() const;
      
     
    

     

      

     
     

      

       LargestUInt asLargestUInt() const;
      
     
    

     

      

     
     

      

       float asFloat() const;
      
     
    

     

      

     
     

      

       double asDouble() const;
      
     
    

     

      

     
     

      

       bool asBool() const;
      
     
   

数组风格

• ValueType::arrayValue 和 ValueType::objectValue 数据类型的访问，操作方式很类似 C++的 vector，可以使用数组风格或者迭代器风格来操作数据。例如：

root["name"] = "milo";

• 下面是相关接口

   

    

     

      

     
     

      

       ArrayIndex size() 
       const;
      
     
    

     

      

     
     

      

       Value& 
       operator[](ArrayIndex 
       index);
      
     
    

     

      

     
     

      

       Value& 
       operator[](int 
       index);
      
     
    

     

      

     
     

      

       const Value& 
       operator[](ArrayIndex 
       index) 
       const;
      
     
    

     

      

     
     

      

       const Value& 
       operator[](int 
       index) 
       const;
      
     
    

     

      

     
     

      

       Value get(ArrayIndex 
       index, 
       const Value& defaultValue) 
       const;
      
     
    

     

      

     
     

      

       const_iterator 
       begin() 
       const;
      
     
    

     

      

     
     

      

       const_iterator 
       end() 
       const;
      
     
    

     

      

     
     

      

       iterator 
       begin();
      
     
    

     

      

     
     

      

       iterator 
       end();
      
     
   

• ValueType::objectValue 数据类型的访问，操作方式很类似 C++的 map

   

    

     

      

     
     

      

       Value& 
       operator[](
       const 
       char* key);
      
     
    

     

      

     
     

      

       const Value& 
       operator[](
       const 
       char* key) 
       const;
      
     
    

     

      

     
     

      

       Value& 
       operator[](
       const JSONCPP_STRING& key);
      
     
    

     

      

     
     

      

       const Value& 
       operator[](
       const JSONCPP_STRING& key) 
       const;
      
     
    

     

      

     
     

      

       Value& 
       operator[](
       const StaticString& key);
      
     
    

     

      

     
     

      

       Value& 
       operator[](
       const CppTL::ConstString& key);
      
     
    

     

      

     
     

      

       const Value& 
       operator[](
       const CppTL::ConstString& key) 
       const;
      
     
    

     

      

     
     

      

       Value get(const char* key, const Value& defaultValue) const;
      
     
    

     

      

     
     

      

       Value get(const char* begin, const char* end, const Value& defaultValue) const;
      
     
    

     

      

     
     

      

       Value get(const JSONCPP_STRING& key, const Value& defaultValue) const;
      
     
    

     

      

     
     

      

       Value get(const CppTL::ConstString& key, const Value& defaultValue) const;
      
     
   

修改数据

• 知道如何获取 Json::Value 对象或其子对象后，我们来看下如何修改 Json::Value 保存 的数据：
• 直接使用=赋值就可以了

Value& operator=(Value other);

• 因为 Json::Value 已经实现了各种数据类型的构造函数

   

    

     

      

     
     

      

       Value(ValueType type = nullValue);
      
     
    

     

      

     
     

      

       Value(Int value);
      
     
    

     

      

     
     

      

       Value(UInt value);
      
     
    

     

      

     
     

      

       Value(Int64 value);
      
     
    

     

      

     
     

      

       Value(UInt64 value);
      
     
    

     

      

     
     

      

       Value(
       double value);
      
     
    

     

      

     
     

      

       Value(
       const 
       char* value);
      
     
    

     

      

     
     

      

       Value(
       const 
       char* begin, 
       const 
       char* end);
      
     
    

     

      

     
     

      

       Value(
       const StaticString& value);
      
     
    

     

      

     
     

      

       Value(
       const JSONCPP_STRING& value);
      
     
    

     

      

     
     

      

       Value(
       const CppTL::ConstString& value);
      
     
    

     

      

     
     

      

       Value(
       bool value);
      
     
    

     

      

     
     

      

       Value(
       const Value& other);
      
     
    

     

      

     
     

      

       Value(Value&& other);
      
     
   

四、注意事项

类型转换

• 对于Int、Uint、Int64、UInt64等类型，注意类型。

root["age"] = 80;  //默认为Int类型

• 可以使用下面的方式进行强制类型转换

root["age"] = (Json::Uint)80;

空值

• 如果要将变量设置为 null，应该使用如下的方式

root["address"] = Json::nullValue;

五、演示案例1

代码如下

• Github源码链接：https://github.com/dongyusheng/csdn-code/tree/master/jsoncpp

   

    

     

      

     
     

      

       #include <iostream>
      
     
    

     

      

     
     

      

       #include <string>
      
     
    

     

      

     
     

      

       #include <jsoncpp/json/json.h>
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       int main()
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "Hello World!" << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::Value root;
      
     
    

     

      

     
     

      

           Json::FastWriter fast;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           root[
       "ModuleType"] = Json::Value(
       1);
      
     
    

     

      

     
     

      

           root[
       "ModuleCode"] = Json::Value(
       "China");
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       std::
       cout<<fast.write(root)<<
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::Value sub;
      
     
    

     

      

     
     

      

           sub[
       "version"] = Json::Value(
       "1.0");
      
     
    

     

      

     
     

      

           sub[
       "city"] = Json::Value(root);
      
     
    

     

      

     
     

      

           fast.write(sub);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       std::
       cout<<sub.toStyledString()<<
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       return 
       0;
      
     
    

     

      

     
     

      

       }
      
     
   

• 编译运行如下： 

g++ jsoncpp_demo01.c -o demo01 -ljsoncpp -std=c++11

六、演示案例2

代码如下

• Github源码链接：https://github.com/dongyusheng/csdn-code/tree/master/jsoncpp

   

    

     

      

     
     

      

       #include <string>
      
     
    

     

      

     
     

      

       #include <jsoncpp/json/json.h>
      
     
    

     

      

     
     

      

       #include <iostream>
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       using 
       namespace 
       std;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       void readJson() {
      
     
    

     

      

     
     

      
	
       std::
       string strValue = 
       "{\"name\":\"json\",\"array\":[{\"cpp\":\"jsoncpp\"},{\"java\":\"jsoninjava\"},{\"php\":\"support\"}]}";
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       	Json::Reader reader;
      
     
    

     

      

     
     

      

       	Json::Value value;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
	
       if (reader.parse(strValue, value))
      
     
    

     

      

     
     

      

       	{
      
     
    

     

      

     
     

      
		
       std::
       string out = value[
       "name"].asString();
      
     
    

     

      

     
     

      
		
       std::
       cout << out << 
       std::
       endl;
      
     
    

     

      

     
     

      
		
       const Json::Value arrayObj = value[
       "array"];
      
     
    

     

      

     
     

      
		
       for (
       unsigned 
       int i = 
       0; i < arrayObj.size(); i++)
      
     
    

     

      

     
     

      

       		{
      
     
    

     

      

     
     

      
			
       if (!arrayObj[i].isMember(
       "cpp")) 
      
     
    

     

      

     
     

      
				
       continue;
      
     
    

     

      

     
     

      

       			out = arrayObj[i][
       "cpp"].asString();
      
     
    

     

      

     
     

      
			
       std::
       cout << out;
      
     
    

     

      

     
     

      
			
       if (i != (arrayObj.size() - 
       1))
      
     
    

     

      

     
     

      
				
       std::
       cout << 
       std::
       endl;
      
     
    

     

      

     
     

      

       		}
      
     
    

     

      

     
     

      

       	}
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       void writeJson() {
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       	Json::Value root;
      
     
    

     

      

     
     

      

       	Json::Value arrayObj;
      
     
    

     

      

     
     

      

       	Json::Value item;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       	item[
       "cpp"] = 
       "jsoncpp";
      
     
    

     

      

     
     

      

       	item[
       "java"] = 
       "jsoninjava";
      
     
    

     

      

     
     

      

       	item[
       "php"] = 
       "support";
      
     
    

     

      

     
     

      

       	arrayObj.append(item);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       	root[
       "name"] = 
       "json";
      
     
    

     

      

     
     

      

       	root[
       "array"] = arrayObj;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       	root.toStyledString();
      
     
    

     

      

     
     

      
	
       std::
       string out = root.toStyledString();
      
     
    

     

      

     
     

      
	
       std::
       cout << out << 
       std::
       endl;
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

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

     

      

     
     

      

       	readJson();
      
     
    

     

      

     
     

      

       	writeJson();
      
     
    

     

      

     
     

      
	
       return 
       0;
      
     
    

     

      

     
     

      

       }
      
     
   

• 编译运行如下：  

g++ jsoncpp_demo02.c -o demo02 -ljsoncpp -std=c++11

七、演示案例3

代码如下

• Github源码链接：https://github.com/dongyusheng/csdn-code/tree/master/jsoncpp

   

    

     

      

     
     

      

       //测试jsoncpp的使用方法和性能
      
     
    

     

      

     
     

      

       #include <memory>
      
     
    

     

      

     
     

      

       #include <sstream>
      
     
    

     

      

     
     

      

       #include <iostream>
      
     
    

     

      

     
     

      

       #include <stdint.h>
      
     
    

     

      

     
     

      

       #include <unistd.h>
      
     
    

     

      

     
     

      

       #include <sys/time.h>
      
     
    

     

      

     
     

      

       #include <sys/wait.h>
      
     
    

     

      

     
     

      

       #include "jsoncpp/json/json.h"
      
     
    

     

      

     
     

      

       #include "jsoncpp/json/value.h"
      
     
    

     

      

     
     

      

       #include "jsoncpp/json/reader.h"
      
     
    

     

      

     
     

      

       #include "jsoncpp/json/writer.h"
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       /*
      
     
    

     

      

     
     

      

       
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      

        "name": "milo",
      
     
    

     

      

     
     

      

        "age": 80,
      
     
    

     

      

     
     

      

        "languages": ["C++", "C"],
      
     
    

     

      

     
     

      

        "phone": {
      
     
    

     

      

     
     

      

        "number": "186****3143",
      
     
    

     

      

     
     

      

        "type": "home"
      
     
    

     

      

     
     

      

        },
      
     
    

     

      

     
     

      

        "books":[
      
     
    

     

      

     
     

      

        {
      
     
    

     

      

     
     

      

        "name": "Linux kernel development",
      
     
    

     

      

     
     

      

        "price":7.7
      
     
    

     

      

     
     

      

        },
      
     
    

     

      

     
     

      

        {
      
     
    

     

      

     
     

      

        "name": "Linux server development",
      
     
    

     

      

     
     

      

        "price": 8.0
      
     
    

     

      

     
     

      

        }
      
     
    

     

      

     
     

      

        ]，
      
     
    

     

      

     
     

      

        "vip":true,
      
     
    

     

      

     
     

      

        "address": null
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      

        */
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       static uint64_t getNowTime()
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       struct timeval tval;
      
     
    

     

      

     
     

      
    
       uint64_t nowTime;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           gettimeofday(&tval, 
       NULL);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           nowTime = tval.tv_sec * 
       1000L + tval.tv_usec / 
       1000L;
      
     
    

     

      

     
     

      
    
       return nowTime;
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       std::
       string JsoncppEncodeNew()
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       std::
       string jsonStr;
      
     
    

     

      

     
     

      
    
       // 一个value是可以包含多个键值对
      
     
    

     

      

     
     

      

           Json::Value root, languages, phone, book, books;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 姓名
      
     
    

     

      

     
     

      

           root[
       "name"] = 
       "milo";
      
     
    

     

      

     
     

      
    
       // 年龄
      
     
    

     

      

     
     

      

           root[
       "age"] = 
       80;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 语言
      
     
    

     

      

     
     

      

           languages[
       0] = 
       "C++";
      
     
    

     

      

     
     

      

           languages[
       1] = 
       "Java";
      
     
    

     

      

     
     

      

           root[
       "languages"] = languages;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 电话
      
     
    

     

      

     
     

      

           phone[
       "number"] = 
       "186****3143";
      
     
    

     

      

     
     

      

           phone[
       "type"] = 
       "home";
      
     
    

     

      

     
     

      

           root[
       "phone"] = phone;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 书籍
      
     
    

     

      

     
     

      

           book[
       "name"] = 
       "Linux kernel development";
      
     
    

     

      

     
     

      

           book[
       "price"] = 
       7.7;
      
     
    

     

      

     
     

      

           books[
       0] = book;    
       // 深拷贝
      
     
    

     

      

     
     

      

           book[
       "name"] = 
       "Linux server development";
      
     
    

     

      

     
     

      

           book[
       "price"] = 
       8.0;
      
     
    

     

      

     
     

      

           books[
       1] = book;    
       // 深拷贝
      
     
    

     

      

     
     

      

           root[
       "books"] = books;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 是否为vip
      
     
    

     

      

     
     

      

           root[
       "vip"] = 
       true;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // address信息空null
      
     
    

     

      

     
     

      

           root[
       "address"] = 
       "yageguoji";
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::StreamWriterBuilder writerBuilder;
      
     
    

     

      

     
     

      
    
       std::
       ostringstream os;
      
     
    

     

      

     
     

      
    
       std::
       unique_ptr<Json::StreamWriter> jsonWriter(writerBuilder.newStreamWriter());
      
     
    

     

      

     
     

      

           jsonWriter->write(root, &os);
      
     
    

     

      

     
     

      

           jsonStr = os.str();
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // std::cout << "Json:\n" << jsonStr << std::endl;
      
     
    

     

      

     
     

      
    
       return jsonStr;
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       std::
       string JsoncppEncodeOld()
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       std::
       string jsonStr;
      
     
    

     

      

     
     

      

           Json::Value root, languages, phone, book, books;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 姓名
      
     
    

     

      

     
     

      

            root[
       "name"] = 
       "milo";
      
     
    

     

      

     
     

      
    
       //root["name"] = Json::nullValue;
      
     
    

     

      

     
     

      
    
       // 年龄
      
     
    

     

      

     
     

      

           root[
       "age"] =  
       80; 
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 语言
      
     
    

     

      

     
     

      

           languages[
       0] = 
       "C++";
      
     
    

     

      

     
     

      

           languages[
       1] = 
       "Java";
      
     
    

     

      

     
     

      

           root[
       "languages"] = languages;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 电话
      
     
    

     

      

     
     

      

           phone[
       "number"] = 
       "186****3143";
      
     
    

     

      

     
     

      

           phone[
       "type"] = 
       "home";
      
     
    

     

      

     
     

      

           root[
       "phone"] = phone;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 书籍
      
     
    

     

      

     
     

      

           book[
       "name"] = 
       "Linux kernel development";
      
     
    

     

      

     
     

      

           book[
       "price"] = (
       float)
       7.7;
      
     
    

     

      

     
     

      

           books[
       0] = book;
      
     
    

     

      

     
     

      

           book[
       "name"] = 
       "Linux server development";
      
     
    

     

      

     
     

      

           book[
       "price"] = (
       float)
       8.0;
      
     
    

     

      

     
     

      

           books[
       1] = book;
      
     
    

     

      

     
     

      

           root[
       "books"] = books;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 是否为vip
      
     
    

     

      

     
     

      

           root[
       "vip"] = 
       true;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // address信息空null
      
     
    

     

      

     
     

      

           root[
       "address"] = 
       "yageguoji"; 
       //;// Json::nullValue; // 如果是null，则要用自定义的Json::nullValue，不能用NULL
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::FastWriter writer;
      
     
    

     

      

     
     

      

           jsonStr = writer.write(root);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // std::cout << "Json:\n" << jsonStr << std::endl;
      
     
    

     

      

     
     

      
    
       return jsonStr;
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       // 不能返回引用
      
     
    

     

      

     
     

      

       Json::
       Value JsoncppEncodeOldGet()
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      

           Json::Value root;
      
     
    

     

      

     
     

      

           Json::Value languages, phone, book, books;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 姓名
      
     
    

     

      

     
     

      

           root[
       "name"] = 
       "milo";
      
     
    

     

      

     
     

      
    
       //root["name"] = Json::nullValue;
      
     
    

     

      

     
     

      
    
       // 年龄
      
     
    

     

      

     
     

      

           root[
       "age"] =  
       80; 
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 语言
      
     
    

     

      

     
     

      

           languages[
       0] = 
       "C++";
      
     
    

     

      

     
     

      

           languages[
       1] = 
       "Java";
      
     
    

     

      

     
     

      

           root[
       "languages"] = languages;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 电话
      
     
    

     

      

     
     

      

           phone[
       "number"] = 
       "186****3143";
      
     
    

     

      

     
     

      

           phone[
       "type"] = 
       "home";
      
     
    

     

      

     
     

      

           root[
       "phone"] = phone;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 书籍
      
     
    

     

      

     
     

      

           book[
       "name"] = 
       "Linux kernel development";
      
     
    

     

      

     
     

      

           book[
       "price"] = (
       float)
       7.7;
      
     
    

     

      

     
     

      

           books[
       0] = book;
      
     
    

     

      

     
     

      

           book[
       "name"] = 
       "Linux server development";
      
     
    

     

      

     
     

      

           book[
       "price"] = (
       float)
       8.0;
      
     
    

     

      

     
     

      

           books[
       1] = book;
      
     
    

     

      

     
     

      

           root[
       "books"] = books;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // 是否为vip
      
     
    

     

      

     
     

      

           root[
       "vip"] = 
       true;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // address信息空null
      
     
    

     

      

     
     

      

           root[
       "address"] = Json::nullValue; 
       //"yageguoji";// Json::nullValue; // 如果是null，则要用自定义的Json::nullValue，不能用NULL
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "JsoncppEncodeOldGet:\n"  << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       return root;
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       void printJsoncpp(Json::Value &root)
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       if(root[
       "name"].isNull())
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      
        
       std::
       cout << 
       "name null\n";
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "name: " << root[
       "name"].asString() << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "age: " << root[
       "age"].asInt() << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::Value &languages = root[
       "languages"];
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "languages: ";
      
     
    

     

      

     
     

      
    
       for (
       uint32_t i = 
       0; i < languages.size(); ++i)
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      
        
       if (i != 
       0)
      
     
    

     

      

     
     

      

               {
      
     
    

     

      

     
     

      
            
       std::
       cout << 
       ", ";
      
     
    

     

      

     
     

      

               }
      
     
    

     

      

     
     

      
        
       std::
       cout << languages[i].asString();
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::Value &phone = root[
       "phone"];
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "phone number: " << phone[
       "number"].asString() << 
       ", type: " << phone[
       "type"].asString() << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::Value &books = root[
       "books"];
      
     
    

     

      

     
     

      
    
       for (
       uint32_t i = 
       0; i < books.size(); ++i)
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      

               Json::Value &book = books[i];
      
     
    

     

      

     
     

      
        
       std::
       cout << 
       "book name: " << book[
       "name"].asString() << 
       ", price: " << book[
       "price"].asFloat() << 
       std::
       endl;
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "vip: " << root[
       "vip"].asBool() << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       if (!root[
       "address"].isNull())
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      
        
       std::
       cout << 
       "address: " << root[
       "address"].asString() << 
       std::
       endl;
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      
    
       else
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      
        
       std::
       cout << 
       "address is null" << 
       std::
       endl;
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       bool JsoncppDecodeNew(const std::string &info)
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       if (info.empty())
      
     
    

     

      

     
     

      
        
       return 
       false;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       bool res;
      
     
    

     

      

     
     

      

           JSONCPP_STRING errs;
      
     
    

     

      

     
     

      

           Json::Value root;
      
     
    

     

      

     
     

      

           Json::CharReaderBuilder readerBuilder;
      
     
    

     

      

     
     

      
    
       std::
       unique_ptr<Json::CharReader> 
       const jsonReader(readerBuilder.newCharReader());
      
     
    

     

      

     
     

      

           res = jsonReader->parse(info.c_str(), info.c_str() + info.length(), &root, &errs);
      
     
    

     

      

     
     

      
    
       if (!res || !errs.empty())
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      
        
       std::
       cout << 
       "parseJson err. " << errs << 
       std::
       endl;
      
     
    

     

      

     
     

      
        
       return 
       false;
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      
    
       // printJsoncpp(root);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       return 
       true;
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       bool JsoncppDecodeOld(const std::string &strJson)
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       if (strJson.empty())
      
     
    

     

      

     
     

      
        
       return 
       false;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       bool res;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::Value root;
      
     
    

     

      

     
     

      

           Json::Reader jsonReader;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           res = jsonReader.parse(strJson, root);
      
     
    

     

      

     
     

      
    
       if (!res)
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      
        
       std::
       cout << 
       "jsonReader.parse err. " << 
       std::
       endl;
      
     
    

     

      

     
     

      
        
       return 
       false;
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       // printJsoncpp(root);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       return 
       true;
      
     
    

     

      

     
     

      

       }
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       const 
       char *strCjson = 
       "{ \
      
     
    

     

      

     
     

      

        \"name\": \"milo\", \
      
     
    

     

      

     
     

      

        \"age\": 80, \
      
     
    

     

      

     
     

      

        \"languages\": [\"C++\", \"C\"],\
      
     
    

     

      

     
     

      

        \"phone\": { \
      
     
    

     

      

     
     

      

        \"number\": \"186****3143\", \
      
     
    

     

      

     
     

      

        \"type\": \"home\" \
      
     
    

     

      

     
     

      

        }, \
      
     
    

     

      

     
     

      

        \"books\": [{ \
      
     
    

     

      

     
     

      

        \"name\": \"Linux kernel development\", \
      
     
    

     

      

     
     

      

        \"price\": 7.700000 \
      
     
    

     

      

     
     

      

        }, { \
      
     
    

     

      

     
     

      

        \"name\": \"Linux server development\", \
      
     
    

     

      

     
     

      

        \"price\": 8 \
      
     
    

     

      

     
     

      

        }], \
      
     
    

     

      

     
     

      

        \"vip\": true, \
      
     
    

     

      

     
     

      

        \"address\": null \
      
     
    

     

      

     
     

      

       } \
      
     
    

     

      

     
     

      

       ";
      
     
    

     

      

     
     

      

       #define TEST_COUNT 100000
      
     
    

     

      

     
     

      

       int main()
      
     
    

     

      

     
     

      

       {
      
     
    

     

      

     
     

      
    
       std::
       string jsonStrNew;
      
     
    

     

      

     
     

      
    
       std::
       string jsonStrOld;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           jsonStrNew = JsoncppEncodeNew();
      
     
    

     

      

     
     

      
    
       // JsoncppEncodeNew size: 337
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "JsoncppEncodeNew size: " << jsonStrNew.size() << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "JsoncppEncodeNew string: " << jsonStrNew << 
       std::
       endl;
      
     
    

     

      

     
     

      

           JsoncppDecodeNew(jsonStrNew);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           jsonStrOld = JsoncppEncodeOld();
      
     
    

     

      

     
     

      
    
       // JsoncppEncodeOld size: 248
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "\n\nJsoncppEncodeOld size: " << jsonStrOld.size() << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "JsoncppEncodeOld string: " << jsonStrOld << 
       std::
       endl;
      
     
    

     

      

     
     

      

           JsoncppDecodeOld(jsonStrOld);
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           Json::Value root = JsoncppEncodeOldGet();
      
     
    

     

      

     
     

      

           Json::FastWriter writer;
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "writer:\n"  << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       std::
       string jsonStr = writer.write(root);
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "\n\njsonStr string: " << jsonStrOld << 
       std::
       endl;
      
     
    

     

      

     
     

      

       #if 1
      
     
    

     

      

     
     

      
    
       uint64_t startTime;
      
     
    

     

      

     
     

      
    
       uint64_t nowTime;
      
     
    

     

      

     
     

      
    
      
     
    

     

      

     
     

      

           startTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "jsoncpp encode time testing" << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       for(
       int i = 
       0; i < TEST_COUNT; i++)
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      

               JsoncppEncodeNew();
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      

           nowTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "jsoncpp encode " << TEST_COUNT << 
       " time, need time: "
      
     
    

     

      

     
     

      

                << nowTime-startTime << 
       "ms"  << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           startTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "\njsoncpp encode time testing" << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       for(
       int i = 
       0; i < TEST_COUNT; i++)
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      

               JsoncppEncodeOld();
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      

           nowTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "jsoncpp encode " << TEST_COUNT << 
       " time, need time: "
      
     
    

     

      

     
     

      

                << nowTime-startTime << 
       "ms"  << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           startTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "\njsoncpp decode time testing" << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       for(
       int i = 
       0; i < TEST_COUNT; i++)
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      

               JsoncppDecodeNew(jsonStrNew);
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      

           nowTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "jsoncpp decode " << TEST_COUNT << 
       " time, need time: "
      
     
    

     

      

     
     

      

                << nowTime-startTime << 
       "ms"  << 
       std::
       endl;
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

           startTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "\njsoncpp decode time testing" << 
       std::
       endl;
      
     
    

     

      

     
     

      
    
       for(
       int i = 
       0; i < TEST_COUNT; i++)
      
     
    

     

      

     
     

      

           {
      
     
    

     

      

     
     

      

               JsoncppDecodeOld(jsonStrNew);
      
     
    

     

      

     
     

      

           }
      
     
    

     

      

     
     

      

           nowTime = getNowTime();
      
     
    

     

      

     
     

      
    
       std::
       cout << 
       "jsoncpp decode " << TEST_COUNT << 
       " time, need time: "
      
     
    

     

      

     
     

      

                << nowTime-startTime << 
       "ms"  << 
       std::
       endl;
      
     
    

     

      

     
     

      

       #endif
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      
    
       return 
       0;
      
     
    

     

      

     
     

      

       }
      
     
   

• 编译运行如下：  

g++ jsoncpp_speed.cpp -o jsoncpp_speed -ljsoncpp -std=c++11