关于cjson库的相关操作方法总结（构造，添加，删除，修改）

 cjson_test.c

#include 
#include 
#include "cJSON.h"
#include 

/**
{
	"name":	"milo",
	"age":	80,
	"professional": {专业
        "english": 4,
        "putonghua": 2,
        "computer": 4
    },
    "languages":	["C++", "C"],
	"phone":	{
		"number":	"18620823143",
		"type":	"home"
	},
	"courses":	[{
			"name":	"Linux kernel development",
			"price":	"7.7"
		}, {
			"name":	"Linux server development",
			"price":	"8.0"
		}],
	"vip":	true,
	"address":	null
}
*/

//打印CJSON
void printfJson(cJSON *json) {
    if (NULL == json) {
        return;
    }
    char *cjson=cJSON_Print(json);//深拷贝
    printf("json:%s\n", cjson);
    free(cjson);
}

//释放
void freeJson(cJSON *json) {
    if (json != NULL) {
        cJSON_Delete(json);
	}
}

//创建JSON
cJSON * createJson() {
    cJSON *json_root=cJSON_CreateObject();
	cJSON_AddItemToObject(json_root, "name", cJSON_CreateString("milo"));
	cJSON_AddNumberToObject(json_root, "age", 80);

    cJSON *json_professional=cJSON_CreateObject();
    cJSON_AddItemToObject(json_professional,"english", cJSON_CreateNumber(4));
    cJSON_AddItemToObject(json_professional,"putonghua", cJSON_CreateNumber(2));
    cJSON_AddItemToObject(json_professional,"computer", cJSON_CreateNumber(3));

    cJSON *json_languages=cJSON_CreateArray();
    cJSON_AddItemToArray(json_languages, cJSON_CreateString("C++"));
    cJSON_AddItemToArray(json_languages, cJSON_CreateString("C"));

    cJSON *json_phone=cJSON_CreateObject();
    cJSON_AddItemToObject(json_phone,"number", cJSON_CreateString("18620823143"));
    cJSON_AddItemToObject(json_phone,"type", cJSON_CreateString("home"));

    cJSON *json_courses = cJSON_CreateArray();
    cJSON* json_pItem1 = cJSON_CreateObject();
    cJSON_AddItemToObject(json_pItem1, "name", cJSON_CreateString("Linux kernel development"));
    cJSON_AddNumberToObject(json_pItem1, "price", 7.7);
    cJSON_AddItemToArray(json_courses, json_pItem1);

    cJSON* json_pItem2 = cJSON_CreateObject();
    cJSON_AddItemToObject(json_pItem2, "name", cJSON_CreateString("Linux server development"));
    cJSON_AddNumberToObject(json_pItem2, "price", 8.8);
    cJSON_AddItemToArray(json_courses, json_pItem2);


    cJSON_AddItemToObject(json_root, "professional", json_professional);
    cJSON_AddItemToObject(json_root, "languages", json_languages);
    cJSON_AddItemToObject(json_root, "phone", json_phone);
    cJSON_AddItemToObject(json_root, "courses", json_courses);

    cJSON_AddBoolToObject(json_root, "vip", 1);
    cJSON_AddNullToObject(json_root, "address");

    return json_root;
}

//已有JSON中添加
//"hobby": ["Basketball", "Football", "badminton"],
void addDataToJson(cJSON *json) {
    if (NULL == json) {
        return;
    }

    cJSON *hobby=cJSON_CreateArray();
    cJSON_AddItemToArray(hobby, cJSON_CreateString("Basketball"));
    cJSON_AddItemToArray(hobby, cJSON_CreateString("Football"));
    cJSON_AddItemToArray(hobby, cJSON_CreateString("badminton"));

    /*
    CJSON_PUBLIC(void) cJSON_AddItemToObject(cJSON *object, const char *string, cJSON *item);
    */
    cJSON_AddItemToObject(json, "hobby", hobby);

    printfJson(json);
}

//修改
//"hobby": ["Basketball", "Football", "badminton"],
//修改为
//"hobby": ["Skating", "dance"],
void updateDataToJson(cJSON *json) {
    if (NULL == json) {
        return;
    }

    cJSON *hobby=cJSON_CreateArray();
    cJSON_AddItemToArray(hobby, cJSON_CreateString("Skating"));
    cJSON_AddItemToArray(hobby, cJSON_CreateString("dance"));

    /*
    CJSON_PUBLIC(void) cJSON_ReplaceItemInArray(cJSON *array, int which, cJSON *newitem);
    CJSON_PUBLIC(void) cJSON_ReplaceItemInObject(cJSON *object,const char *string,cJSON *newitem);
    */
    cJSON_ReplaceItemInObject(json, "hobby", hobby);

    printfJson(json);
}

//删除
//"hobby": ["Skating", "dance"],
void deleteDataToJson(cJSON *json) {
    if (NULL == json) {
        return;
    }

    /*
    CJSON_PUBLIC(cJSON *) cJSON_DetachItemFromObject(cJSON *object, const char *string);
    */
    cJSON_DetachItemFromObject(json, "hobby");

    printfJson(json);
}

//解析JSON
void analysisJsonObj(cJSON *json) {
    if (NULL == json) {
        return;
    }

    cJSON *json_name = cJSON_GetObjectItem(json, "name");
    printf("root[%s:%s]\n", json_name->string, json_name->valuestring);

    cJSON *json_age = cJSON_GetObjectItem(json, "age");
    printf("root[%s:%d]\n", json_age->string, json_age->valueint);

    cJSON *json_professional = cJSON_GetObjectItem(json, "professional");
    cJSON *json_professional_child = json_professional->child;
    while (json_professional_child != NULL) {
        printf("%s[%s:%d]\n", json_professional->string, json_professional_child->string, json_professional_child->valueint);
        json_professional_child = json_professional_child->next;

    }
    cJSON *json_languages = cJSON_GetObjectItem(json, "languages");
    if (json_languages) {
        int size = cJSON_GetArraySize(json_languages);
        printf("%s size:%d\n", json_languages->string, size);
        for (int i = 0; i < size; i++) {
            cJSON *json_languages_child =cJSON_GetArrayItem(json_languages, i);
            printf("%s[%d:%s]\n", json_languages->string, i, json_languages_child->valuestring);
        }
    }

    cJSON *json_phone = cJSON_GetObjectItem(json, "phone");
    cJSON *json_phone_number = cJSON_GetObjectItem(json_phone,"number");
    cJSON *json_phone_type = cJSON_GetObjectItem(json_phone,"type");
    printf("%s[%s:%s]\n", json_phone->string, json_phone_number->string, json_phone_number->valuestring);
    printf("%s[%s:%s]\n", json_phone->string, json_phone_type->string, json_phone_type->valuestring);

    cJSON *json_courses = cJSON_GetObjectItem(json, "courses");
    if (json_courses) {
        int size = cJSON_GetArraySize(json_courses);
        printf("%s size:%d\n", json_courses->string, size);
        for(int i=0;istring, json_course_name->string, json_course_name->valuedouble);
                printf("%s[%s:%.1lf]\n", json_courses->string, json_course_price->string, json_course_price->valuedouble);
            }
        }
    }

    cJSON *json_vip = cJSON_GetObjectItem(json, "vip");

    if (json_vip->type == cJSON_True) {
        printf("root[%s:true]\n", json_vip->string);
    } else if (json_vip->type == cJSON_False) {
        printf("root[%s:false]\n", json_vip->string);
    } else {
        printf("root[%s:false]\n", json_vip->string);
    }

//    cJSON_Bool bvip = cJSON_IsBool(json_vip);
//    if (bvip == cJSON_True) {//cJSON_False
//        printf("root[%s:true]\n", json_vip->string);
//    } else {
//        printf("root[%s:false]\n", json_vip->string);
//    }

    cJSON *json_address = cJSON_GetObjectItem(json, "address");
    if (json_address->type ==cJSON_NULL) {
        printf("root[%s:null]\n", json_address->string);
    }
}


static void printJsonObjvalue(const cJSON *json) {
    if (NULL == json) {
        printf("NULL object!\n");
        return;
    }

    switch (json->type) {
        case cJSON_False:
            printf("%s: false\n", json->string);
            break;
        case cJSON_True:
            printf("%s: true\n", json->string);
            break;
        case cJSON_NULL:
            printf("%s: cJSON_NULL\n", json->string);
            break;
        case cJSON_Number:
            printf("%s: %d, %f\n", json->string, json->valueint, json->valuedouble);
            break;
        case cJSON_String:
            printf("%s: %s\n", json->string, json->valuestring);
            break;
        case cJSON_Array:
            printf("%s: cJSON_Array\n", json->string);
            break;
        case cJSON_Object:
            printf("%s: cJSON_Object\n", json->string);
            break;
        default:
            printf("unknown type\n");
            break;
    }
}

void analysisJsonPrint(cJSON *json) {
    if (NULL == json) {
        return;
    }

    cJSON *json_name = cJSON_GetObjectItem(json, "name");
    printJsonObjvalue(json_name);

    cJSON *json_age = cJSON_GetObjectItem(json, "age");
    printJsonObjvalue(json_age);

    cJSON *json_professional = cJSON_GetObjectItem(json, "professional");
    cJSON *json_professional_child = json_professional->child;
    while (json_professional_child != NULL) {
        printJsonObjvalue(json_professional_child);
        json_professional_child = json_professional_child->next;
    }

    cJSON *json_languages = cJSON_GetObjectItem(json, "languages");
    if (NULL == json_languages) {
        int size = cJSON_GetArraySize(json_languages);
        printf("%s size:%d\n", json_languages->string, size);
        for (int i = 0; i < size; i++) {
            cJSON *json_languages_child = cJSON_GetArrayItem(json_languages, i);
            printJsonObjvalue(json_languages_child);
        }
    }

    cJSON *json_phone = cJSON_GetObjectItem(json, "phone");
    cJSON *json_phone_number = cJSON_GetObjectItem(json_phone,"number");
    cJSON *json_phone_type = cJSON_GetObjectItem(json_phone,"type");
    printJsonObjvalue(json_phone_number);
    printJsonObjvalue(json_phone_type);

    cJSON *json_courses = cJSON_GetObjectItem(json, "courses");
    if (json_courses) {
        int size = cJSON_GetArraySize(json_courses);
        printf("%s size:%d\n", json_courses->string, size);
        for(int i=0;i

 

comment_test.c  文件形式

#include 
#include 
#include 
#include "cJSON.h"
#include 


//评论
typedef struct COMMENT
{
    int user_id;
    int msg_id;
    char* comment;
    int click_count;
    int like_count;
    int reply_count;
    int is_new_reply;
    long add_time;
} COMMENT;

//获取当前时间毫秒数
long getCurrentTime()
{
    struct timeval tv;
    gettimeofday(&tv,NULL);
    //毫秒
    long time_sec = tv.tv_sec*1000 + tv.tv_usec/1000;

    return time_sec;
}

//打印CJSON
void printfJson(cJSON *json) {
    if (NULL == json) {
        return;
    }
    char *cjson=cJSON_Print(json);//深拷贝
    printf("json:%s\n", cjson);
    free(cjson);
}

void freeComment(COMMENT *comment) {
    if (comment != NULL) {
        if (comment->comment != NULL) {
            free(comment->comment);
            comment->comment = NULL;
        }

        free(comment);
        comment = NULL;
    }
}

void freeJson(cJSON *json) {
    if (json != NULL) {
        cJSON_Delete(json);
	}
}

/**
json对象
{
    "user_id":1,
    "msg_id":1,
    "comment":"json",
    "click_count":0,
    "like_count":0,
    "reply_count":0,
    "is_new_reply":0,
    "add_time":0,
}
*/
//将结构体转成cJSON
cJSON *convertToJson(COMMENT *comment) 
{
    if (comment == NULL) {
        return NULL;
    }

    //创建json
    cJSON *json=cJSON_CreateObject();
    //将 "user_id" 添加到 "json" 节点. 
	cJSON_AddNumberToObject(json, "user_id", comment->user_id);
	cJSON_AddNumberToObject(json, "msg_id", comment->msg_id);

    cJSON_AddItemToObject(json, "comment", cJSON_CreateString(comment->comment));
    cJSON_AddNumberToObject(json, "click_count", comment->click_count);
    cJSON_AddNumberToObject(json, "like_count", comment->like_count);
    cJSON_AddNumberToObject(json, "reply_count", comment->reply_count);
    cJSON_AddNumberToObject(json, "is_new_reply", comment->is_new_reply);
    cJSON_AddNumberToObject(json, "add_time", comment->add_time);

    return json;
}

//将cJSON赋值给结构体
COMMENT* convertToComment(cJSON *json)
{  
    if (NULL == json) {
        return NULL;
    }
   
    cJSON *json_user_id = cJSON_GetObjectItem(json, "user_id");
    cJSON *json_msg_id = cJSON_GetObjectItem(json, "msg_id");
    cJSON *json_comment = cJSON_GetObjectItem(json, "comment");
    cJSON *json_click_count = cJSON_GetObjectItem(json, "click_count");
    cJSON *json_like_count = cJSON_GetObjectItem(json, "like_count");
    cJSON *json_reply_count = cJSON_GetObjectItem(json, "reply_count");
    cJSON *json_is_new_reply = cJSON_GetObjectItem(json, "is_new_reply");
    cJSON *json_add_time = cJSON_GetObjectItem(json, "add_time");

    COMMENT *comment = (COMMENT *)malloc(sizeof(COMMENT));
    comment->user_id = json_user_id->valueint;
    comment->msg_id = json_msg_id->valueint;
    comment->comment=(char *)malloc(256);
    memset(comment->comment, 0, 256);
    strcat(comment->comment, json_comment->valuestring);
    comment->click_count = json_click_count->valueint;
    comment->like_count = json_like_count->valueint;
    comment->reply_count = json_reply_count->valueint;
    comment->is_new_reply = json_is_new_reply->valueint;
    comment->add_time = (long)(json_add_time->valuedouble);

    return comment;
}

void readJsonFromData(char *data) {
    cJSON *json=cJSON_Parse(data);//将data数据构建成cJSON结构
    //打印json
    printfJson(json);

    COMMENT* comment = convertToComment(json);
    if (comment != NULL) {
        
        comment->like_count = 77;
        comment->reply_count = 99;

        //转为json
        cJSON *childjson = convertToJson(comment);
        //打印json
        printfJson(childjson);
        //释放对象
        freeComment(comment);
        //
        freeJson(childjson);
	}
    freeJson(json);
}

//保存JSON
void writeJsonFile(cJSON *json) {
    if (NULL == json) {
        return;
    }

    char *cjson=cJSON_Print(json);

    FILE *fp = NULL;
    char *fileName = "./comment.json";
    fp = fopen(fileName, "w+");
    if (NULL != fp) {
        fwrite(cjson, strlen(cjson),1,fp);
        fclose(fp);
	}
    if (cjson != NULL) {
        free(cjson);
	}
}

//读取JSON
void readJsonFile() {
    FILE *fp = NULL;
    char *out;
    char line[1024] = {0};
    char *fileName = "./comment.json";

    //打开一个文本文件，文件必须存在，只允许读
    fp = fopen(fileName, "r");
    //seek末尾
    fseek(fp, 0, SEEK_END);
    //读取文件大小
    long len = ftell(fp);
    //seek起始位值
    fseek(fp, 0, SEEK_SET);
    char *data = (char*)malloc(len + 1);
    fread(data, 1, len, fp);
    if (fp != NULL) {
        fclose(fp);
	}

    //读取
    readJsonFromData(data);
    
    if (NULL != data) {
        free(data);
    }
}

COMMENT *createComment() {
    COMMENT *comment = (COMMENT *)malloc(sizeof(COMMENT));
    comment->user_id = 1;
    comment->msg_id = 10000;
    comment->comment=(char *)malloc(256);
    memset(comment->comment, 0, 256);
    sprintf(comment->comment, "我赞同楼主");
    comment->click_count = 0;
    comment->like_count = 0;
    comment->reply_count = 0;
    comment->is_new_reply = 0;
    comment->add_time = getCurrentTime();
    return comment;
}

void test1() {
    COMMENT *comment = createComment();

    //转为json
    cJSON *json = convertToJson(comment);
    
    //保存json
    writeJsonFile(json);

    freeComment(comment);

    freeJson(json);
}

void test2() {
    //读取json
    readJsonFile();
}

int main(int argc, char *argv[]) {
    
    test1();

    test2();

    return 0;
}

comment.json

{
	"user_id":	1,
	"msg_id":	10000,
	"comment":	"我赞同楼主",
	"click_count":	0,
	"like_count":	0,
	"reply_count":	0,
	"is_new_reply":	0,
	"add_time":	1591502300323
}

 

gcc cJSON.c cjson_test.c  -o cjson_test -lm
gcc cJSON.c comment_test.c -o comment_test -lm