使用cjson进行对象的嵌套封装

共分两个部分，1）创建json、2）解析json

1）创建嵌套json的代码

char * makeJson()
{
    cJSON * pRoot = NULL;
    cJSON * pSub_1 = NULL;
    cJSON * pSub_2 = NULL;

    if((pRoot = cJSON_CreateObject()) == NULL)
    {
        return NULL;
    }
    if((pSub_1 = cJSON_CreateObject()) == NULL)
    {
        return NULL;
    }
    if((pSub_2 = cJSON_CreateObject()) == NULL)
    {
        return NULL;
    }
    cJSON_AddStringToObject(pSub_2, "cStr", "ccccccc");

    cJSON_AddStringToObject(pSub_1, "bStr", "bbbbbbb");
    cJSON_AddItemToObject(pSub_1, "subobject_2", pSub_2);

    cJSON_AddStringToObject(pRoot, "aStr", "aaaaaaa");
    cJSON_AddItemToObject(pRoot, "subobject_1", pSub_1);
    cJSON_AddStringToObject(pRoot, "xStr", "xxxxxxx");

    //cJSON_PrintUnformatted : make json string for Unformatted
    //char * pJson = cJSON_PrintUnformatted(pRoot);

    char * pJson = cJSON_Print(pRoot);
    if(NULL == pJson)
    {
        cJSON_Delete(pRoot);
        return NULL;
    }
    return pJson;
}

2）解析json的代码

int parseJson(const char * pJson)
{
    if(NULL == pJson)
    {
        return ;
    }
    cJSON * pRoot = cJSON_Parse(pJson);
    if(NULL == pRoot)
    {
        return ;
    }
    cJSON * pSub_1 = cJSON_GetObjectItem(pRoot, "aStr");
    if(NULL == pSub_1)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get aStr : [%s]\n", pSub_1->valuestring);
    pSub_1 = cJSON_GetObjectItem(pRoot, "xStr");
    if(NULL == pSub_1)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get xStr : [%s]\n", pSub_1->valuestring);
    pSub_1 = cJSON_GetObjectItem(pRoot, "subobject_1");
    if(NULL == pSub_1)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get Sub Obj 1\n");
    cJSON * pSub_2 = cJSON_GetObjectItem(pSub_1, "bStr");
    if(NULL == pSub_2)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get bStr : [%s]\n", pSub_2->valuestring);
    pSub_2 = cJSON_GetObjectItem(pSub_1, "subobject_2");
    if(NULL == pSub_2)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get Obj 2\n");
    cJSON * pStr = cJSON_GetObjectItem(pSub_2, "cStr");
    if(NULL == pStr)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get cStr : [%s]\n", pStr->valuestring);

    cJSON_Delete(pRoot);
    return ;
}

3）主函数

int main()
{
    char * pJson = makeJson();
    printf("JSON:\n%s\n", pJson);
    parseJson(pJson);
    free(pJson);

    return ;
}

完整的代码请打开下面的代码或到百度网盘下载 http://pan.baidu.com/s/1pJ7KZSR

#include <stdio.h>
#include "cJSON.h"

char * makeJson()
{
    cJSON * pRoot = NULL;
    cJSON * pSub_1 = NULL;
    cJSON * pSub_2 = NULL;

    if((pRoot = cJSON_CreateObject()) == NULL)
    {
        return NULL;
    }
    if((pSub_1 = cJSON_CreateObject()) == NULL)
    {
        return NULL;
    }
    if((pSub_2 = cJSON_CreateObject()) == NULL)
    {
        return NULL;
    }
    cJSON_AddStringToObject(pSub_2, "cStr", "ccccccc");

    cJSON_AddStringToObject(pSub_1, "bStr", "bbbbbbb");
    cJSON_AddItemToObject(pSub_1, "subobject_2", pSub_2);

    cJSON_AddStringToObject(pRoot, "aStr", "aaaaaaa");
    cJSON_AddItemToObject(pRoot, "subobject_1", pSub_1);
    cJSON_AddStringToObject(pRoot, "xStr", "xxxxxxx");

    //cJSON_PrintUnformatted : make json string for Unformatted
    //char * pJson = cJSON_PrintUnformatted(pRoot);

    char * pJson = cJSON_Print(pRoot);
    if(NULL == pJson)
    {
        cJSON_Delete(pRoot);
        return NULL;
    }
    return pJson;
}

int parseJson(const char * pJson)
{
    if(NULL == pJson)
    {
        return ;
    }
    cJSON * pRoot = cJSON_Parse(pJson);
    if(NULL == pRoot)
    {
        return ;
    }
    cJSON * pSub_1 = cJSON_GetObjectItem(pRoot, "aStr");
    if(NULL == pSub_1)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get aStr : [%s]\n", pSub_1->valuestring);
    pSub_1 = cJSON_GetObjectItem(pRoot, "xStr");
    if(NULL == pSub_1)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get xStr : [%s]\n", pSub_1->valuestring);
    pSub_1 = cJSON_GetObjectItem(pRoot, "subobject_1");
    if(NULL == pSub_1)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get Sub Obj 1\n");
    cJSON * pSub_2 = cJSON_GetObjectItem(pSub_1, "bStr");
    if(NULL == pSub_2)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get bStr : [%s]\n", pSub_2->valuestring);
    pSub_2 = cJSON_GetObjectItem(pSub_1, "subobject_2");
    if(NULL == pSub_2)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get Obj 2\n");
    cJSON * pStr = cJSON_GetObjectItem(pSub_2, "cStr");
    if(NULL == pStr)
    {
        cJSON_Delete(pRoot);
        return ;
    }
    printf("get cStr : [%s]\n", pStr->valuestring);

    cJSON_Delete(pRoot);
    return ;
}

int main()
{
    char * pJson = makeJson();
    printf("JSON:\n%s\n", pJson);
    parseJson(pJson);
    free(pJson);

    return ;
}

编译

$ gcc -o nestcjson nestcjson.c cjson.c -lm

注：编译时链接的库 -lm 是数学库，不加此库时 gcc 返回错误，错误代码如下

$ gcc -o nestcjson nestcjson.c cjson.c
/tmp/ccugp95L.o: In function `parse_number':
cjson.c:(.text+0x402): undefined reference to `pow'
/tmp/ccugp95L.o: In function `print_number':
cjson.c:(.text+0x512): undefined reference to `floor'
collect2: ld 返回 1

运行

$ ./nestcjson
JSON:
{
    "aStr":    "aaaaaaa",
    "subobject_1":    {
        "bStr":    "bbbbbbb",
        "subobject_2":    {
            "cStr":    "ccccccc"
        }
    },
    "xStr":    "xxxxxxx"
}
get aStr : [aaaaaaa]
get xStr : [xxxxxxx]
get Sub Obj
get bStr : [bbbbbbb]
get Obj
get cStr : [ccccccc]

作者：风波

mail : fengbohello@qq.com