Python 入门教程（十一）：综合实战——命令行待办事项管理器

1
import json
2
import os
3
from datetime import datetime
4

5
DATA_FILE = "todos.json"
6

7
def load_todos():
8
    """读取数据文件；不存在或损坏时返回空列表（健壮性）"""
9
    if not os.path.exists(DATA_FILE):
10
        return []
11
    try:
12
        with open(DATA_FILE, encoding="utf-8") as f:
13
            return json.load(f)
14
    except (json.JSONDecodeError, OSError):
15
        print("⚠ 数据文件损坏，已重置")
16
        return []
17

18
def save_todos(todos):
19
    with open(DATA_FILE, "w", encoding="utf-8") as f:
20
        json.dump(todos, f, ensure_ascii=False, indent=2)

1
VALID_PRIORITIES = {"high": "🔴高", "mid": "🟡中", "low": "🟢低"}
2

3
def next_id(todos):
4
    return max((t["id"] for t in todos), default=0) + 1
5

6
def add_todo(todos, title, priority="mid", due=None):
7
    """新增任务，返回新任务"""
8
    if priority not in VALID_PRIORITIES:
9
        raise ValueError(f"优先级必须是 {list(VALID_PRIORITIES)}")
10
    if due:
11
        try:
12
            datetime.strptime(due, "%Y-%m-%d")    # 校验日期格式
13
        except ValueError:
14
            raise ValueError("日期格式应为 YYYY-MM-DD")
15
    todo = {
16
        "id": next_id(todos),
17
        "title": title.strip(),
18
        "priority": priority,
19
        "due": due,
20
        "done": False,
21
        "created": datetime.now().strftime("%Y-%m-%d %H:%M"),
22
    }
23
    todos.append(todo)
24
    save_todos(todos)
25
    return todo
26

27
def finish_todo(todos, todo_id):
28
    """标记完成，返回该任务；不存在抛 KeyError"""
29
    for t in todos:
30
        if t["id"] == todo_id:
31
            t["done"] = True
32
            save_todos(todos)
33
            return t
34
    raise KeyError(f"找不到编号 {todo_id} 的任务")
35

36
def delete_todo(todos, todo_id):
37
    for i, t in enumerate(todos):
38
        if t["id"] == todo_id:
39
            removed = todos.pop(i)
40
            save_todos(todos)
41
            return removed
42
    raise KeyError(f"找不到编号 {todo_id} 的任务")
43

44
def query(todos, status="all", priority=None):
45
    """筛选：status = all/todo/done；priority = high/mid/low"""
46
    result = todos
47
    if status == "todo":
48
        result = [t for t in result if not t["done"]]
49
    elif status == "done":
50
        result = [t for t in result if t["done"]]
51
    if priority:
52
        result = [t for t in result if t["priority"] == priority]
53
    return result
54

55
def is_overdue(todo):
56
    """已过期：未完成且截止日早于今天"""
57
    if todo["done"] or not todo["due"]:
58
        return False
59
    return todo["due"] < datetime.now().strftime("%Y-%m-%d")

1
def print_todos(todos, title="任务列表"):
2
    if not todos:
3
        print("（空空如也）")
4
        return
5
    print(f"\n== {title} ==")
6
    print(f"{'ID':<5}{'状态':<6}{'优先级':<8}{'截止':<12}标题")
7
    print("-" * 50)
8
    for t in todos:
9
        status = "✅" if t["done"] else ("⏳" if not is_overdue(t) else "❗逾期")
10
        due = t["due"] or "-"
11
        print(f"{t['id']:<5}{status:<6}{VALID_PRIORITIES[t['priority']]:<6}"
12
              f"{due:<12}{t['title']}")
13

14
def print_stats(todos):
15
    total = len(todos)
16
    done = sum(1 for t in todos if t["done"])
17
    overdue = sum(1 for t in todos if is_overdue(t))
18
    rate = done / total * 100 if total else 0
19
    print(f"\n📊 统计：共 {total} 项｜完成 {done} 项"
20
          f"（{rate:.0f}%）｜逾期 {overdue} 项")

1
def main():
2
    todos = load_todos()
3
    print("=== 待办事项管理器 ===")
4
    print("命令：add 标题 [优先级] [日期] / list [all|todo|done] / "
5
          "done 编号 / del 编号 / stats / quit")
6

7
    while True:
8
        try:
9
            raw = input("\n> ").strip()
10
            if not raw:
11
                continue
12
            parts = raw.split(maxsplit=3)      # 最多拆 4 段，标题保留空格
13
            cmd, args = parts[0].lower(), parts[1:]
14

15
            if cmd == "quit":
16
                print("再见！")
17
                break
18

19
            elif cmd == "add":
20
                title = args[0] if args else ""
21
                if not title:
22
                    print("用法：add 标题 [high|mid|low] [YYYY-MM-DD]")
23
                    continue
24
                priority = args[1] if len(args) > 1 and args[1] in VALID_PRIORITIES else "mid"
25
                due = args[2] if len(args) > 2 else None
26
                t = add_todo(todos, title, priority, due)
27
                print(f"✅ 已添加 #{t['id']} {t['title']}")
28

29
            elif cmd == "list":
30
                status = args[0] if args and args[0] in ("all", "todo", "done") else "todo"
31
                print_todos(query(todos, status=status), f"筛选:{status}")
32

33
            elif cmd == "done":
34
                finish_todo(todos, int(args[0]))
35
                print("🎉 已完成！")
36

37
            elif cmd == "del":
38
                delete_todo(todos, int(args[0]))
39
                print("🗑 已删除")
40

41
            elif cmd == "stats":
42
                print_stats(todos)
43

44
            else:
45
                print("未知命令，输入 quit 退出")
46

47
        except KeyError as e:
48
            print(f"操作失败：{e}")
49
        except ValueError as e:
50
            print(f"参数错误：{e}")
51
        except IndexError:
52
            print("缺少参数，请检查命令格式")
53
        except KeyboardInterrupt:
54
            print("\n再见！")
55
            break
56

57
if __name__ == "__main__":      # 第八篇：可直接运行，也可被导入复用
58
    main()