利用rapidjson实现未知json数据的解析，拿到每一个key和value，用vs2010实现。

引用头文件

#include "rapidjson/document.h"

#include <string>

using namespace std;

using namespace rapidjson;

程序段

string strJsonTest = "{\"item_1\":\"value_1\",\"item_2\":\"value_2\",\"item_3\":\"value_3\",\"item_4\":\"value_4\",\"item_arr\":[\"arr_vaule_1\",\"arr_vaule_2\"]}";
Document docTest;
docTest.Parse<0>(strJsonTest.c_str());

if (!docTest.HasParseError())
{
        for (rapidjson::Value::ConstMemberIterator itr = docTest.MemberBegin(); itr != docTest.MemberEnd(); itr++)
        {
                Value jKey;
                Value jValue; 
                Document::AllocatorType allocator;
                jKey.CopyFrom(itr->name, allocator);
                jValue.CopyFrom(itr->value,allocator);
               if (jKey.IsString())
               {
                       string name = jKey.GetString();
                       printf("\r\nname: %s\r\n",name.c_str());
               } 
        } 
}

利用jsoncpp实现未知json数据的解析，拿到每一个key和value，用vs2010实现。

Json::Value valRoot;
Json::Reader reader;

        if (!reader.parse(strJson, valRoot))
        {
            return JSON_PARSE_ERR;
        }
        
        Json::Value::Members members;
        members = valRoot.getMemberNames();
        for (Json::Value::Members::iterator iterMember = members.begin(); iterMember != members.end(); iterMember++)
        {
            std::string strKey = *iterMember;
            if (valRoot[strKey.c_str()].isString())
            {
                std::string strVal = valRoot[strKey.c_str()].asString();
                std::cout<<strKey.c_str()<<":"<<strVal.c_str()<<std::endl;
            }
            else if (valRoot[strKey.c_str()].isInt())
            {
                int iVal = valRoot[strKey.c_str()].asInt();
                std::cout<<strKey.c_str()<<":"<<iVal<<std::endl;
            }
            else if (valRoot[strKey.c_str()].isDouble())
            {
                double dVal = valRoot[strKey.c_str()].asDouble();
                std::cout<<strKey.c_str()<<":"<<dVal<<std::endl;
            }
            else
            {
                std::string strVal = valRoot[strKey.c_str()].toStyledString();
                std::cout<<strKey.c_str()<<":"<<strVal.c_str()<<std::endl;
            }
        }

提供两个函数例子实现：

jsoncpp：

int PrintJsonString(const std::string& strJson)
    {
        Json::Value valRoot;
        Json::Reader reader;

        if (!reader.parse(strJson, valRoot))
        {
            return -1;
        }
        
        Json::Value::Members members;
        members = valRoot.getMemberNames();
        for (Json::Value::Members::iterator iterMember = members.begin(); iterMember != members.end(); iterMember++)
        {
            std::string strKey = *iterMember;
            if (valRoot[strKey.c_str()].isString())
            {
                std::string strVal = valRoot[strKey.c_str()].asString();
                std::cout<<strKey.c_str()<<":"<<strVal.c_str()<<std::endl;
            }
            else if (valRoot[strKey.c_str()].isInt())
            {
                int iVal = valRoot[strKey.c_str()].asInt();
                std::cout<<strKey.c_str()<<":"<<iVal<<std::endl;
            }
            else if (valRoot[strKey.c_str()].isDouble())
            {
                double dVal = valRoot[strKey.c_str()].asDouble();
                std::cout<<strKey.c_str()<<":"<<dVal<<std::endl;
            }
            else
            {
                std::string strVal = valRoot[strKey.c_str()].toStyledString();
                std::cout<<strKey.c_str()<<":"<<strVal.c_str()<<std::endl;
            }
        }

        return 0;
    }

rapidjson：

std::string JsonToString(rapidjson::Value& valRoot)
    {
        rapidjson::StringBuffer strBuf;
        strBuf.Clear();
        rapidjson::Writer<rapidjson::StringBuffer> writer(strBuf);
        valRoot.Accept(writer);
        std::string strJson = strBuf.GetString();
        return strJson;
    }

int PrintJsonString(const std::string& strJson)
    {
        int iStart = strJson.find("{");
        int iEnd = strJson.rfind("}");
        if ((iStart < 0) || (iEnd < 1) || (iStart > iEnd))
        {
            return -1;
        }
        std::string strTemp = strJson.substr(iStart, (iEnd - iStart + 1));    
        
        rapidjson::Document doc;
        
        doc.Parse(strTemp.c_str());
        if (doc.HasParseError())
        {
            return -1;
        }

	rapidjson::Document::AllocatorType& allocator = doc.GetAllocator();

        for (rapidjson::Value::ConstMemberIterator iter = doc.MemberBegin(); iter != doc.MemberEnd(); iter++)
        {
            rapidjson::Value jKey;
            rapidjson::Value jValue;            
            
            jKey.CopyFrom(iter->name, allocator);
            jValue.CopyFrom(iter->value, allocator);

            if (jKey.IsString())
            {
                std::string strKey = jKey.GetString();  
                if (jValue.IsString())
                {
                    std::string strVal = jValue.GetString();
                    std::cout<<strKey.c_str()<<":"<<strVal.c_str()<<std::endl;
                }
                else if (jValue.IsInt())
                {
                    int iVal = jValue.GetInt();
                    std::cout<<strKey.c_str()<<":"<<iVal<<std::endl;
                }
                else if (jValue.IsDouble())
                {
                    double dVal = jValue.GetDouble();
                    std::cout<<strKey.c_str()<<":"<<dVal<<std::endl;
                }
                else
                {
                    std::string strVal = JsonToString(jValue);
                    std::cout<<strKey.c_str()<<":"<<strVal.c_str()<<std::endl;
                }
            }
        }

        return 0;
    }