一.看了《Head First Design Pattern》的觀察者模式的學習筆記
The Observer Pattern defines a one-to-many dependency between objects so that when one object changes state, all of its dependents are notified and updated automatically.
1.氣象監測應用的結構圖
氣象站：獲取實際氣象數據的物理裝置。
WeatherData對象：追蹤來自氣象站的數據，並更新佈告板。
佈告板：顯示當前天氣狀況給用戶看。
2.氣象站設計圖
