cJSON使用

时间 2020-05-23

标签 cjson 使用栏目 JSON 繁體版

原文原文链接

c语言源码下载地址：https://github.com/DaveGamble/cJSONgit

其余语言源码下载地址：http://www.json.org/github

用 cJSON_PrintUnformatted(root) 或者 cJSON_Print(root);来将json对象转换成普通的字符串，而且都是以该json对象的根为基点。两个API的区别便是：一个是没有格式的：也就是转换出的字符串中间不会有"\n" "\t"之类的东西存在，而cJSON_Print(root);打印出来是人看起来很舒服的格式。仅此而已。json

cJSON的使用

JSON格式的生产

如下代码不须要执行cJSON_Delete(sub_js)，由于删除父CJSON对象时，会删除子CJSON对象数组

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spa

{ "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（读取JSON格式数据，只要是在同一个{}内，不须要从上往下按顺序读，支持乱序）

{ "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格式数据debug

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); }

建立带数组的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);