JSON 下 -- jansson 示例

JSON 下 —— jansson 示例

参考网址：

jansson 库的下载：

http://www.digip.org/jansson/

安装jansson 步骤：

http://blog.csdn.net/lz909/article/details/46042979

jansson 手册：

https://jansson.readthedocs.io/en/latest/index.html

API 介绍：

http://jansson.readthedocs.io/en/2.2/apiref.html#json_error_t

vim source.c

 #include<stdio.h>
 #include<string.h>
 #include<jansson.h>

 #define FILE_PATH         "./temp.txt"
 #define MAX_NUM            5

 typedef struct _JSON_ITEM_INFO
 {
     json_t* string;
     json_t* value;
 }JSON_ITEM_INFO;

 void save_info_to_file()
 {
    json_t* root = NULL;
    json_t* item_1 = NULL;
    json_t* item_2 = NULL;
    json_t* item_3 = NULL;
    json_t* array = NULL;

    char* s_repon = NULL;

    root = json_object();
    item_1 = json_object();
    item_2 = json_object();
    item_3 = json_object();
    array = json_array();

    json_object_set_new(item_1,"name",json_string("xiaopeng"));
    json_object_set_new(item_1,"age",json_integer());
    json_array_append_new(array,item_1);

    json_object_set_new(item_2,"name",json_string("xiaoming"));
    json_object_set_new(item_2,"age",json_integer());
    json_array_append_new(array,item_2);

    json_object_set_new(item_3,"name",json_string("xiaohong"));
    json_object_set_new(item_3,"age",json_integer());
    json_array_append_new(array,item_3);

    json_object_set_new(root,"root",array);

    json_dump_file(root, FILE_PATH,JSON_PRESERVE_ORDER);

    s_repon = json_dumps(root,JSON_INDENT());

    printf("s_repon = %s \n",s_repon);
    free(s_repon);

    printf("size = %d \n", (int)json_array_size(array));

    if(root)
    {
       json_delete(root);
    }
    if(array)
    {
       json_delete(array);
    }
 }

 void get_file_info()
 {
    int i = ;

    json_t* root = NULL;
    json_t* array = NULL;
    json_error_t error;
    char* s_repon = NULL;

    json_t* add_item_1 = NULL;
    char* s_get_add_item = NULL;

    json_t* rec_table[MAX_NUM] = {};

    JSON_ITEM_INFO person[MAX_NUM];
    memset(person,,sizeof(person));

    //get the info from file;
    root = json_load_file(FILE_PATH, , &error);
    if(!json_is_object(root))
    {
         printf("%s,%d\n",__FILE__,__LINE__);
    }
    s_repon = json_dumps(root,JSON_INDENT());
    printf("s_repon = %s \n",s_repon);
    free(s_repon);

    array = json_object_get(root,"root");
    if(!json_is_array(array))
    {
         printf("%s,%d\n",__FILE__,__LINE__);
    }

    for(i = ; i < MAX_NUM ;i++)
    {
        rec_table[i] = json_array_get(array,i);
        if(!json_is_object(rec_table[i]))
        {
             printf("%s,%d\n",__FILE__,__LINE__);
        }
        person[i].string = json_object_get(rec_table[i],"name");
        printf("person[%d].string = %s \n",i,json_string_value(person[i].string));
        person[i].value = json_object_get(rec_table[i],"age");
        printf("person[%d].value = %d \n",i,(int)json_integer_value(person[i].value));
    }

     //add the new item;
     add_item_1 = json_object();
     json_object_set_new(add_item_1,"name",json_string("zhangsan"));
     json_object_set_new(add_item_1,"age",json_integer());

    if(json_array_size(array) >= MAX_NUM)
    {
         //remove the top item;
         json_array_remove(array,);

    }
     json_array_append_new(array,add_item_1);

     //write the new array to the file;
     json_dump_file(root, FILE_PATH,JSON_PRESERVE_ORDER);

     //dump the date and print
     s_get_add_item = json_dumps(root,JSON_INDENT());

     printf("s_get_add_item = %s \n",s_get_add_item);
     free(s_get_add_item);

 }

 int main()
 {
     save_info_to_file(); //这里将数据保存在文件 FILE_PATH 里；
     get_file_info();     // 这里将文件 FILE_PATH 数据读取出来；

     return ;
 }

编译：

gcc source.c -ljansson

执行结果：

有什么错漏，欢迎指出！！！