cJSON使用

c語言源碼下載地址：https://github.com/DaveGamble/cJSON

其餘語言源碼下載地址：http://www.json.org/

 

用 cJSON_PrintUnformatted(root) 或者 cJSON_Print(root);來將json對象轉換成普通的字符串，而且都是以該json對象的根爲基點。兩個API的區別便是：一個是沒有格式的：也就是轉換出的字符串中間不會有"\n" "\t"之類的東西存在，而cJSON_Print(root);打印出來是人看起來很舒服的格式。僅此而已。

 

 

cJSON的使用

 

 

JSON格式的生產 

如下代碼不須要執行cJSON_Delete(sub_js)，由於刪除父CJSON對象時，會刪除子CJSON對象

cJSON *root=NULL; cJSON *sub_js=NULL; char *out=NULL; root = cJSON_CreateObject(); cJSON_AddStringToObject(root, "ver", "v1.0.0"); cJSON_AddStringToObject(root, "did", "066EFF3638324D4D43183319"); cJSON_AddStringToObject(root, "hardware_ver", "V1.0.0"); cJSON_AddStringToObject(root, "software_ver", "V1.0.0"); cJSON_AddItemToObject(root, "data", sub_js = cJSON_CreateObject()); cJSON_AddNumberToObject(sub_js, "status", 1); cJSON_AddTrueToObject(sub_js, "material"); cJSON_AddTrueToObject(sub_js, "power_on"); cJSON_AddNumberToObject(sub_js, "qty", 123); cJSON_AddStringToObject(root, "dt", "2017-11-04T05:15:52"); out=cJSON_Print(root); cJSON_Delete(root); debug("%s\n",out); free(out);

打印出

{ "ver":    "v1.0.0", "did":    "066EFF3638324D4D43183319", "hardware_ver":    "V1.0.0", "software_ver":    "V1.0.0", "data": { "status":    1, "material":    true, "power_on":    true, "qty":    123 }, "dt":    "2017-11-04T05:15:52" }

 

解析JSON格式（讀取JSON格式數據，只要是在同一個{}內，不須要從上往下按順序讀，支持亂序）

{ "wifi": { "ssid":    "hello World", "pwd":    "234sdlfkj23" }, "mqtt": { "server":    "192.168.31.240", "port":    1883, "clientid":    "asdfghjklzxcvbnm", "username":    "1234567asdfghj", "password":    "asdfghjkerty" }, "option": { "working_signal_last_time":    15, "material_empty_signal_last_time":    6, "material_full_signal_last_time":    3, "status_send_time":    30 } }

 UART_RxBuf_tmp就是上面的JSON格式數據

char *out; cJSON *json, *item1, *item2; json=cJSON_Parse((char const *)UART_RxBuf_tmp); if (!json) { debug("Error before:%s\n",cJSON_GetErrorPtr()); } else { item1 = cJSON_GetObjectItem(json, "wifi"); item2 = cJSON_GetObjectItem(item1, "ssid"); debug("%s: %s", item2->string, item2->valuestring); item2 = cJSON_GetObjectItem(item1, "pwd"); debug("%s: %s", item2->string, item2->valuestring); debug("%s",wifi_information); item1 = cJSON_GetObjectItem(json, "mqtt"); item2 = cJSON_GetObjectItem(item1, "server"); debug("%s: %s", item2->string, item2->valuestring); item2 = cJSON_GetObjectItem(item1, "port"); debug("%s: %d", item2->string, item2->valueint); debug("%s",server_information); item2 = cJSON_GetObjectItem(item1, "clientid"); debug("%s: %s", item2->string, item2->valuestring); item2 = cJSON_GetObjectItem(item1, "username"); debug("%s: %s", item2->string, item2->valuestring); item2 = cJSON_GetObjectItem(item1, "password"); debug("%s: %s", item2->string, item2->valuestring); item1 = cJSON_GetObjectItem(json, "option"); item2 = cJSON_GetObjectItem(item1, "working_signal_last_time"); debug("%s: %d", item2->string, item2->valueint); item2 = cJSON_GetObjectItem(item1, "material_empty_signal_last_time"); debug("%s: %d", item2->string, item2->valueint); item2 = cJSON_GetObjectItem(item1, "material_full_signal_last_time"); debug("%s: %d", item2->string, item2->valueint); item2 = cJSON_GetObjectItem(item1, "status_send_time"); debug("%s: %d", item2->string, item2->valueint); out=cJSON_Print(json); cJSON_Delete(json); debug("%s\n",out); free(out); }

 

建立帶數組的JSON

cJSON *root=NULL; cJSON *sub_js=NULL; char *out=NULL; root = cJSON_CreateObject(); cJSON_AddStringToObject(root, "ver", protocol_ver); cJSON_AddStringToObject(root, "did", (char const*)g_MCU_uniqueID_str); cJSON_AddStringToObject(root, "hardware_ver", hardware_ver); cJSON_AddStringToObject(root, "software_ver", software_ver); cJSON_AddItemToObject(root, "data", sub_js = cJSON_CreateObject()); cJSON *array; array = cJSON_CreateArray(); cJSON_AddItemToObject(sub_js, "M", array); cJSON_AddItemToArray(array, cJSON_CreateBool(1)); cJSON_AddItemToArray(array, cJSON_CreateBool(1)); cJSON_AddItemToArray(array, cJSON_CreateBool(1)); cJSON_AddItemToArray(array, cJSON_CreateBool(0)); cJSON_AddItemToArray(array, cJSON_CreateBool(0)); array = cJSON_CreateArray(); cJSON_AddItemToObject(sub_js, "D", array); cJSON_AddItemToArray(array, cJSON_CreateNumber(12312)); cJSON_AddItemToArray(array, cJSON_CreateNumber(12334)); cJSON_AddItemToArray(array, cJSON_CreateNumber(967425)); char time[20]; get_formatted_time(time); cJSON_AddStringToObject(root, "dt", (char const*)time); out=cJSON_Print(root); cJSON_Delete(root); debug("%s\n",out); MQTT_publish(out, "init"); vPortFree(out);