### 实现12306车票余量查询 要使用Python实现12306车票余量查询，主要依赖于`requests`模块发起HTTP请求获取数据，并通过解析返回的数据来显示所需的信息。此外，由于12306有其特定的车站编码表，在构建查询URL时需要用到这些编码。 #### 准备工作 首先需要安装必要的第三方库： ```bash pip install requests prettytable ``` 接着准备一份包含所有火车站名及其对应编号映射关系的JSON文件，这可以通过访问官方API或其他途径获得[^3]。 #### 编写代码逻辑 创建一个新的Python脚本并导入所需的包： ```python import json from datetime import datetime import requests from prettytable import PrettyTable ``` 定义函数用于加载本地存储的站点字典： ```python def load_stations(): with open('stations.json', 'r') as f: stations = json.load(f) return {v:k for k, v in stations.items()} ``` 设置查询参数模板及目标网址： ```python url_template = "https://kyfw.12306.cn/otn/leftTicket/queryTicketPrice" headers = { 'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64)', } params = {} ``` 编写核心查询方法： ```python def query_ticket(departure_station_name, arrival_station_name, date_str): station_map = load_stations() params['train_no'] = '' params['fromStation'] = station_map.get(departure_station_name.upper()) params['toStation'] = station_map.get(arrival_station_name.upper()) try: d = datetime.strptime(date_str,"%Y-%m-%d").date() params['depart_date'] = str(d) response = requests.get(url=url_template, headers=headers, params=params) if not response.status_code == 200: raise Exception("Failed to fetch data") result = response.json()['data']['result'] table = PrettyTable(['Train No.', 'Start Time', 'Arrive Time', 'Duration']) for item in result: train_info = item.split('|') row = [ train_info[3], # Train number train_info[8], # Start time train_info[9], # Arrive time train_info[10] # Duration ] table.add_row(row) print(table) except KeyError as e: print(f"Invalid input parameter: {e}") except ValueError as ve: print(ve) except Exception as ex: print(ex) ``` 此段代码实现了基于给定出发站、到达站和日期的基础查询功能[^2]。