定义 Define an interface for creating an object,but let subclasses decide which class to instantiate.Factory Method lets ...

Ensure a class has only one instance, and provide a global point of access to it.（确保某一个类只有一个实例，而且自行实例化并向整个系统提供这个实例。） 类...

运用设计模式，需要记住六大设计原则： Single Responsibility Principle：单一职责原则 Open Closed Principle：开闭原则 Liskov Substitution Principle：里氏替换...