[整理][RapidJson用法1]C++之RapidJson解析嵌套数组json

因为工作需要，需要对一段嵌套的json进行解析。其中我使用的开发语言是C++。

由于rapidjson的解析效率高效，所以今天研究了下RapidJson，下面是一段我用RapidJson解析的一段具有嵌套数组的json文本代码。

JSON文本如下：

{
  "Info": [
    {
      "lots": 10,
      "order_algorithm": "01",
      "buy_close": 9000,
      "spread_shift": 0,
      "position_b_sell": 0,
      "position_a_buy_today": 0,
      "position_a_buy_yesterday": 0,
      "sell_open": -9000,
      "list_instrument_id": [
        "rb1705",
        "rb1701"
      ],
      "position_b_buy_today": 0,
      "buy_open": -9000,
      "position_a_sell_yesterday": 0,
      "strategy_id": "02",
      "position_b_buy": 0,
      "a_wait_price_tick": 1,
      "trade_model": "boll_reversion",
      "b_wait_price_tick": 0,
      "sell_close": 9000,
      "only_close": 0,
      "order_action_limit": 400,
      "is_active": 1,
      "lots_batch": 1,
      "position_a_sell": 0,
      "position_b_buy_yesterday": 0,
      "user_id": "063802",
      "position_a_buy": 0,
      "trader_id": "1601",
      "position_a_sell_today": 0,
      "stop_loss": 0,
      "position_b_sell_today": 0,
      "position_b_sell_yesterday": 0,
      "on_off": 0
    },
    {
      "lots": 10,
      "order_algorithm": "01",
      "buy_close": 9000,
      "spread_shift": 0,
      "position_b_sell": 0,
      "position_a_buy_today": 0,
      "position_a_buy_yesterday": 0,
      "sell_open": -9000,
      "list_instrument_id": [
        "ni1705",
        "ni1701"
      ],
      "position_b_buy_today": 0,
      "buy_open": -9000,
      "position_a_sell_yesterday": 0,
      "strategy_id": "01",
      "position_b_buy": 0,
      "a_wait_price_tick": 1,
      "trade_model": "boll_reversion",
      "b_wait_price_tick": 0,
      "sell_close": 9000,
      "only_close": 0,
      "order_action_limit": 400,
      "is_active": 1,
      "lots_batch": 1,
      "position_a_sell": 0,
      "position_b_buy_yesterday": 0,
      "user_id": "063802",
      "position_a_buy": 0,
      "trader_id": "1601",
      "position_a_sell_today": 0,
      "stop_loss": 0,
      "position_b_sell_today": 0,
      "position_b_sell_yesterday": 0,
      "on_off": 0
    }
  ],
  "MsgSendFlag": 0,
  "MsgErrorReason": "ID or password error",
  "MsgRef": 1,
  "MsgType": 3,
  "MsgResult": 0
}

解析其格式的C++代码如下，我只解析关键部分，其余读者可以自行添加。

#include "rapidjson/document.h"
#include "rapidjson/writer.h"
#include "rapidjson/stringbuffer.h"
#include <iostream>

using namespace rapidjson;
int main() {
    // 1. Parse a JSON string into DOM.
    const char* json ="{\"Info\":[{\"lots\":10,\"order_algorithm\":\"01\",\"buy_close\":9000,\"spread_shift\":0,\"position_b_sell\":0,\"position_a_buy_today\":0,\"position_a_buy_yesterday\":0,\"sell_open\":-9000,\"list_instrument_id\":[\"rb1705\",\"rb1701\"],\"position_b_buy_today\":0,\"buy_open\":-9000,\"position_a_sell_yesterday\":0,\"strategy_id\":\"02\",\"position_b_buy\":0,\"a_wait_price_tick\":1,\"trade_model\":\"boll_reversion\",\"b_wait_price_tick\":0,\"sell_close\":9000,\"only_close\":0,\"order_action_limit\":400,\"is_active\":1,\"lots_batch\":1,\"position_a_sell\":0,\"position_b_buy_yesterday\":0,\"user_id\":\"063802\",\"position_a_buy\":0,\"trader_id\":\"1601\",\"position_a_sell_today\":0,\"stop_loss\":0,\"position_b_sell_today\":0,\"position_b_sell_yesterday\":0,\"on_off\":0},{\"lots\":20,\"order_algorithm\":\"02\",\"buy_close\":9000,\"spread_shift\":0,\"position_b_sell\":0,\"position_a_buy_today\":0,\"position_a_buy_yesterday\":0,\"sell_open\":-9000,\"list_instrument_id\":[\"ni1705\",\"ni1701\"],\"position_b_buy_today\":0,\"buy_open\":-9000,\"position_a_sell_yesterday\":0,\"strategy_id\":\"01\",\"position_b_buy\":0,\"a_wait_price_tick\":1,\"trade_model\":\"boll_reversion\",\"b_wait_price_tick\":0,\"sell_close\":9000,\"only_close\":0,\"order_action_limit\":400,\"is_active\":1,\"lots_batch\":1,\"position_a_sell\":0,\"position_b_buy_yesterday\":0,\"user_id\":\"063802\",\"position_a_buy\":0,\"trader_id\":\"1601\",\"position_a_sell_today\":0,\"stop_loss\":0,\"position_b_sell_today\":0,\"position_b_sell_yesterday\":0,\"on_off\":0}],\"MsgSendFlag\":0,\"MsgErrorReason\":\"IDorpassworderror\",\"MsgRef\":1,\"MsgType\":3,\"MsgResult\":0}";
    //std::cout << json << std::endl;
	//std::cout << "\n" << std::endl;
	std::cout << "|==================|" << std::endl;
	std::cout << "||rapidjson output||" << std::endl;
	std::cout << "|==================|" << std::endl;
	Document doc;
    doc.Parse(json);
	
    // 2. Modify it by DOM.
    Value& s = doc["MsgSendFlag"];
    s.SetInt(s.GetInt() + 1);
	
	Value& infoArray = doc["Info"];
	if (infoArray.IsArray()) {
		for (int i = 0; i < infoArray.Size(); i++) {
			const Value& object = infoArray[i];
			int lots = object["lots"].GetInt();
			std::string order_algorithm = object["order_algorithm"].GetString();
			std::cout << "int lots = " << lots << std::endl;
			std::cout << "string order_algorithm = " << order_algorithm << std::endl;
			const Value& info_object = object["list_instrument_id"];
			if (info_object.IsArray()) {
				for (int j = 0; j < info_object.Size(); j++) {
					std::string instrument = info_object[j].GetString();
					std::cout << "instrument[" << j << "] = " << instrument << std::endl;
				}
			}
		}
	}
	
    // 3. Stringify the DOM
    StringBuffer buffer;
    Writer<StringBuffer> writer(buffer);
    doc.Accept(writer);
    std::cout << buffer.GetString() << std::endl;
    return 0;
}

运行结果如下：

参考：http://stackoverflow.com/questions/23170718/rapidjson-get-a-value-inside-an-array-of-another-array

http://www.cnblogs.com/ziyouchutuwenwu/p/3790322.html

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