记录在使用C++的过程中的一些代码实现。

C++二维数组解析Json对象数组(旧方法)

JSON文件

example.json
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{
"type":"HJ212-2017",
"cycle":60,
"host":"192.168.101.114",
"port":5095,
"mn":"12345678",
"st":"12",
"cn":"34",
"pw":"56",
"cp":
[
{"n":"abc","dt":"4N.0","ds":"LB33","len":1,"group":"1"},
{"n":"bcd","dt":"C2.0","ds":"LB0","len":1,"group":"2"},
{"n":"cde","dt":"YYYY0.0","ds":"LB11","len":4,"group":"3"},
{"n":"qwexxx","dt":"N2.3","ds":"LW78","len":13,"group":"4"},
{"n":"qwettt","dt":"YYYY0.0","ds":"LW5","len":123,"group":"4"}
]
}

JSON结构体

struct
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typedef struct {
    string n_;			///< Instruction parameter field name.
    string dt_;			///< Instruction parameter data type and integer bit and decimal places.
    string ds_;			///< Instruction parameter data source.
    uint32_t len_;		///< Instruction parameter ?.
    string group_;	    ///< Instruction parameter group.
} JSON_CHA_D;

typedef struct {
    string type_;		///< Support protocol type.
    uint32_t cycle_;	///< The cycle to reported data.
    string host_;		///< The reported data of server address.
    int port_;          ///< The reporeted data of server port.

    string mn_;			///< Equipment number(MN).
    string st_;			///< System coding(ST).
    string cn_;			///< Command code(CN).
    string pw_;			///< Access password(PW).
} JSON_STA_D;

处理JSON对象数组到二维数组

GetJsonApi
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#include <jsoncpp/json/json.h>

int Hj212Service::GetJson(void)
{
    char path[256];
    strcpy(path, "./example.json", 14);
    string json_file_path_ = path;
    JSON_STA_D *pjs_sta = new JSON_STA_D;
    this->GetJsonSta(json_file_path_, pjs_sta);
    
    int len;
    this->GetJsonChaLen(json_file_path_, &len);
    JSON_CHA_D **pjs_cha = new JSON_CHA_D *[len];

    for (int i = 0; i < len; i++) {
        pjs_cha[i] = new JSON_CHA_D;
    }

-----------------------------------------------------------------------------------------------
/***           How to Get the json object logic to A two-dimensional array.                ***/
-----------------------------------------------------------------------------------------------
    // Get json arry object.
    ifstream ifs(json_file_path_.c_str());
    Json::Reader reader;
    Json::Value d;

    // Judge json file is existed.
    bool ret = reader.parse(ifs, d);
    if (ret == false) {
        printf("Parse ReadConfig() json data error.\n");
        ifs.close();
        return -1;
    }
    ifs.close();

    // Get the json normal key.
    js_d->type_ = d["type"].asString();
    js_d->cycle_ = d["cycle"].asUInt();
    js_d->host_ = d["host"].asString();
    js_d->port_ = d["port"].asUInt();
    js_d->mn_ = d["mn"].asString();
    js_d->st_ = d["st"].asString();
    js_d->cn_ = d["cn"].asString();
    js_d->pw_ = d["pw"].asString();

    // Parse json arrayObj.
    const Json::Value arrayObj = d["cp"];
    // Get directive parameter(cp) json data.
    for (int i = 0; i < arrayObj.size(); i++) {
        pjs_cha[i]->n_ = arrayObj[i]["n"].asString();
        pjs_cha[i]->dt_ = arrayObj[i]["dt"].asString();
        pjs_cha[i]->ds_ = arrayObj[i]["ds"].asString();
        pjs_cha[i]->len_ = stoi(arrayObj[i]["len"].asString());
        pjs_cha[i]->group_ = arrayObj[i]["group"].asString();
    }

    cout << pjs_sta->type_ << endl;
    cout << pjs_sta->cycle_ << endl;
    cout << pjs_sta->host_ << endl;
    cout << pjs_sta->port_ << endl;
    cout << pjs_sta->mn_ << endl;
    cout << pjs_sta->st_ << endl;
    cout << pjs_sta->cn_ << endl;

    for (int i = 0; i < len; i++) {
        cout << pjs_cha[i]->n_ << endl;
        cout << pjs_cha[i]->dt_ << endl;
        cout << pjs_cha[i]->ds_ << endl;
        cout << pjs_cha[i]->len_ << endl;
        cout << pjs_cha[i]->group_ << endl;
    }

    for (int i = 0; i < len; i++) {
        delete pjs_cha[i];
    }

    delete pjs_sta;
    delete[] pjs_cha;

    return 0;
}

解析只有JSON对象的Json文件(旧方法)

JSON文件

test.json
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[
	{"a":"1", "b":"2", "c":"3"},
	{"a":"4", "b":"5", "c":"6"},
	{"a":"7", "b":"8", "c":"9"}
]

处理DEMO

demo.cpp
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#include <iostream>
#include <fstream>
#include <jsoncpp/json/json.h>

using namespace std;

int main()
{
	/**  Test.json content.
	[
	{"a":"1", "b":"2", "c":"3"},
	{"a":"4", "b":"5", "c":"6"},
	{"a":"7", "b":"8", "c":"9"}
    ]
	*/
	char path[256] = "./test.json";

	// Get json arry object.
	// ifstream param must be char array or char *.
	string path_ = path;
    ifstream ifs(path_.c_str());
    // Follow is Errno using.
    // ifstream ifs(path_);
    Json::Reader reader;
    // Parse json arrayObj.
    Json::Value arrayObj;

    // Judge json file is existed.
    bool ret = reader.parse(ifs, arrayObj);
    if (ret == false) {
    	std::cout << "Parse ReadConfig() json data error." << std::endl;
        ifs.close();
        return -1;
    }
    ifs.close();

    // Get directive parameter(cp) json data.
    for (int i = 0; i < arrayObj.size(); i++) {
   		std::cout << arrayObj[i]["a"].asString() << std::endl;
   		std::cout << arrayObj[i]["b"].asString() << std::endl;
   		std::cout << arrayObj[i]["c"].asString() << std::endl;
    }

	return 0;
}

创建JSON格式数据(旧方法)

构建JSON数据

demo.c
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#include <iostream>
#include <jsoncpp/json/json.h>
#include <fstream>

using namespace std;

int main() {
    // Create the characters array json object.
    Json::Value ch;
    ch[0]["name"] = "Jabberwock";
    ch[0]["chapter"] = 1;
    ch[1]["name"] = "Cheshire Cat";
    ch[1]["chapter"] = 6;
    ch[2]["name"] = "Mad Hatter";
    ch[2]["chapter"] = 7;

    // Create the json array not key.
    Json::Value ary;
    ary[0] = "Zhang san";
    ary[1] = "Li shi";
    ary[2] = "Xiao hong";
    ary[3] = "Xiao ming";

    // create the main object.
    Json::Value val;
    val["book"] = "Alice in Wonderland";
    val["year"] = 1865;
    val["win"] = true;
    val["characters"] = ch;
    val["name"] = ary;

    // Output json ch.
    cout << ch << '\n';

    // Output json by closely.
    Json::FastWriter out;
    cout << out.write(val) << '\n';

    // Output json by normal.
    Json::StyledWriter out1;
    cout << out1.write(val) << '\n';

    // Output json to file.
    ofstream fjson;
    fjson.open("demo.json");
    fjson << out1.write(val);
    fjson.close();
}

正则JSON末尾的换行

regex.cpp
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#include <boost/regex.hpp>
#include <iostream>
#include <string>

using namespace::boost;
using namespace::std;

void test(void)
{
	// regex re("(https?://www.ttufo.com/.+/.+/.+)(_\\d+)(.html?)");
	// string target("http://www.ttufo.com/ufo/201705/154053_3.html");
	regex re("(.*)\\r\\n$");
	string target("##0101QN=20160801085857223;ST=32;CN=1062;PW=100000;MN=010000A8900016F000169DC0;Flag=5;CP=&&RtdInterval=30&&1C80\r\n");
    // NOTE: cmatch is meaning char *, smatch is string
	cmatch what;
    // smatch what;

	if (regex_match(target.c_str(), what, re)) {
    // if (regex_match(target, what, re)) {
		cout << "match " << what.size() << endl;

		for (int i = 0; i < what.size(); i++) {

			cout << "what[" << i << "]: " << what[i] << endl;
		}
	} else {
		cout << "not match " << endl;
	}
}

int main(void)
{
	test();
	return 0;
}

消除FastJson末尾产生的换行

RemFastJsonLastNewline.cpp
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/**
 * @brief Remove the Json::FastWriter transfer json string last \r\n symbol.
 * @param[out] The need Remover \r\n symbol json string.
 * @note The Api not long time test, maybe have bug.
 */
void RemFastJsonLastNewline(string *json_string)
{   
    // The follow code can erase string last symbol(blank_space\t\f\v\n\r).
    // std::string whitespaces (" \t\f\v\n\r");
    // FIXME: The implementation maybe have bug.
    std::string whitespaces ("\n\r");
    std::size_t found = json_string->find_last_not_of(whitespaces);
    if (found != std::string::npos)
        json_string->erase(found + 1);
    else
        json_string->clear();
}

解析未知格式的JsonApi

1.解析的json数据格式文件

file.json
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{
   "book" : "Alice in Wonderland",
   "year" : 1865,
   "win" : true,
   "result" : false,
   "data" : [
      {
         "0x80000000":"12.5"
      },
      {
         "0x80000001":"220"
      },
      {
         "0x80000002":"80.5"
      }
   ],
   "name" : [ "Zhang san", "Li shi", "Xiao hong" ],
   "string" : "Good Bye.",
   "string.c_str" : "Good Bye."
}

2.解析json的示例代码(旧方法)

unpack_unknown_json.cpp
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#include <iostream>
#include <fstream>
#include <jsoncpp/json/json.h>

using namespace std;

void unknow_json_traversal(Json::Value d)
{   
    // Jsoncpp function type() can judge 8 type is nullValue, intValue, uintValue, 
    // realValue, stringValue, booleanValue, arrayValue, objectValue.
    // The json type detaile can visit http://jsoncpp.sourceforge.net/value_8h_source.html#l00036. 
    int cnt;
    // Return a list of the member names. 
    Json::Value::Members mem = d.getMemberNames();
    // Traversal json members by jsoncpp iterator.
    for (Json::Value::Members::iterator iter = mem.begin(); iter != mem.end(); iter++) {
        // The members of key.
        cout << *iter << " : ";
        // Judge the member value of type.
        switch (d[*iter].type()) {
        case Json::objectValue:
            cout << endl;
            // Recursion parse the json object.
            unknow_json_traversal(d[*iter]);
            break;
        // When the member of type is jsonarray, it maybe array object or multiple array elements.
        case Json::arrayValue:
            cout << endl;
            // Get the json array elements numbers.
            cnt = d[*iter].size();
            for (int i = 0; i < cnt; i++) {
                switch (d[*iter][i].type()) {
                // Recursion parse the json array object value of type.
                case Json::objectValue:
                    unknow_json_traversal(d[*iter][i]);
                    break;
                // Json array object type of value is string.
                case Json::stringValue:
                    std::cout << d[*iter][i].asString() << std::endl;
                    break;
                // Json array object type of value is float of double.
                case Json::realValue:
                    std::cout << d[*iter][i].asDouble() << std::endl;
                    break;
                // Json array object type of value is unsigned int.
                case Json::uintValue:
                    std::cout << d[*iter][i].asUInt() << std::endl;
                    break;
                // Json array object type of value is int.
                case Json::intValue:
                    std::cout << d[*iter][i].asInt() << std::endl;
                    break;
                }
            }
            break;
        // Json member object type of value is string.
        case Json::stringValue:
            std::cout << d[*iter].asString() << std::endl;
            break;
        // Json member object type of value is float of double.
        case Json::realValue:
            std::cout << d[*iter].asDouble() << std::endl;
            break;
        // Json member object type of value is unsigned int.
        case Json::uintValue:
            std::cout << d[*iter].asUInt() << std::endl;
            break;
        // Json member object type of value is int.
        case Json::intValue:
            std::cout << d[*iter].asInt() << std::endl;
            break;
        // Json member object type of value is bool.
        case Json::booleanValue:
            std::cout << d[*iter].asBool() << std::endl;
            // The asBool output value is 1 or 0.
            if (d[*iter].asBool()) {
                // If the asBool return 1 is true.
                cout << "true" << endl;
            } else {
                // If the asBool return 0 is false.
                cout << "false" << endl;
            }
            break;
        // Json member object type of value is null.
        case Json::nullValue:
            return;
            break;
        }
    }
    return;
}

int main()
{
    char path[256] = "./demo.json";

    // Get json arry object.
    // ifstream param must be char array or char *.
    string path_ = path;
    ifstream ifs(path_.c_str());
    // Follow is Errno using.
    // ifstream ifs(path_);
    Json::Reader reader;
    // Parse json arrayObj.
    Json::Value arrayObj;

    // Judge json file is existed.
    bool ret = reader.parse(ifs, arrayObj);
    if (ret == false) {
        std::cout << "Parse ReadConfig() json data error." << std::endl;
        ifs.close();
        return -1;
    }
    ifs.close();

    unknow_json_traversal(arrayObj);

    return 0;
}

新Jsoncpp的使用(新方法)

创建Json

jsoncpp可能不支持中文输出而将中文转为unicode编码

Create.cpp
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Json::Value root;
Json::Value sub;

root["name"] = "xiao hong";
root["age"] = 32;
root["school"] = "东大";

sub["name"] = "xiao ming";
sub["age"] = 33;
sub["school"] = "大阪";

root["man"] = sub;

Json::StreamWriterBuilder builder;
builder["commentStyle"] = "None";
builder["indentation"] = "";

// one way
std::unique_ptr<Json::StreamWriter> writer(builder.newStreamWriter());
std::ostringstream os;
writer->write(root, &os);
std::string str = os.str();
std::cout << str << std::endl;

// two way
Json::StreamWriterBuilder wbuilder;
// Configure the Builder, then ...
std::string outputConfig = Json::writeString(wbuilder, root);

解析Json

parse.cpp
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//解析json文件

// one way
#include <fstream>

std::ifstream config_doc("config_doc.json", std::ifstream::binary);
config_doc >> root;

// two way
Json::Value root;
Json::CharReaderBuilder rbuilder;
// Configure the Builder, then ...
std::string errs;
bool parsingSuccessful = Json::parseFromStream(rbuilder, config_doc, &root, &errs);
if (!parsingSuccessful)
{
    // report to the user the failure and their locations in the document.
    std::cout  << "Failed to parse configuration\n"
               << errs;
    return;
}

char strBuf[]="{ \"id\":666, \"name\":\"henryHe\"}";
std::istringstream iss(strBuf);  
Json::Value readValue;
Json::CharReaderBuilder rbuilder;
rbuilder["collectComments"] = false;
std::string errs;
bool parsingSuccessful = Json::parseFromStream(rbuilder, iss , &readValue, &errs);
if (!parsingSuccessful)
{
    // report to the user the failure and their locations in the document.
    std::cout  << "Failed to parse configuration\n"
               << errs;
    return;
}
cout <<"id: "<< readValue["id"] << endl;
cout <<"name: "<< readValue["name"] << endl;

// 解析字符串
string sRecv = "{name = \"xiao hong\"}";
JSONCPP_STRING errs; 
Json::Value root;
Json::CharReaderBuilder readerBuilder;
int res;

// 这一步可以一步判断json格式是否合法
std::unique_ptr<Json::CharReader> const jsonReader(readerBuilder.newCharReader());
res = jsonReader->parse(sRecv.c_str(), sRecv.c_str() + sRecv.length(), &root, &errs);
if (!res || !errs.empty()) {
	std::cout << "parseJson err. " << errs << std::endl;
	return -1;
}

C++队列API

Queue Push Api

SetQueue.cpp
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/**
 * @brief Set substract size pack string to queue.
 * @param[in] *send_pack_queue The save string queue.
 * @param[in] int part_size The substract size.
 * @param[in] int part_size The each substract size pack.
 * @note 
 */
void SetQueue(queue<string> *send_pack_queue, string *pack_string, int part_size)
{
    // Judge the queue is empty.
    if (!send_pack_queue->empty()) {
        LOG(ERROR) << "The SetSendPackToQueue of Send subpack queue is not empty!";
        // Empty the queue;
        while (!send_pack_queue->empty()) {
            send_pack_queue->pop();
        }
    }
    int total_size = pack_string->size();

    // Get the pack part number.
    int pack_part_n = total_size / part_size + 1;

    // Set the pack to queue.
    string tmp_pack;
    for (int i = 0; i < pack_part_n; i++) {
        // When the substr size is more than residual value size, it can get residual value size.
        if ( i == pack_part_n - 1) {
            tmp_pack = pack_string->substr(0, pack_string->size());
            send_pack_queue->push(tmp_pack);
            break;
        }
        tmp_pack = pack_string->substr(0, part_size);
        send_pack_queue->push(tmp_pack);
        // When the last pack is not len as the part size the erase will segmentation fault.
        pack_string->erase(pack_string->begin(), pack_string->begin() + part_size);
        tmp_pack.clear();
    }
}

Queue Pop

GetQueue Api

GetQueue.cpp
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/**
 * @brief Get string from queue.
 * @param *send_pack_queue The save string queue.
 * @param *send_pack_string The pop pack string.
 */
void GetQueue(queue<string> *send_pack_queue, string *send_pack_string)
{
    // Judge the queue is empty.
    if (send_pack_queue->empty()) {
        LOG(ERROR) << "The GetSendPackToQueue of queue is empty.!";
        return;
    }

    // Get the data from queue.
    *send_pack_string = send_pack_queue->front();
    send_pack_queue->pop();
}

完整取出Queue Demo

Demo.cpp
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string test_line = "1234567891011121314151617181920212223242526272829";
string test_line_ = test_line;
string show_str;
queue<string> t_q;

SetQueue(&t_q, &test_line_, 9);

string s_string;
while (!t_q.empty()) {
    GetQueue(&t_q, &s_string);
    cout << s_string.c_str() << "  NUM:" << s_string.size() << endl;
}