Head-First-Design-mode

代码说明：

  你将学到为何利用其他开发人员的经验与智慧解决问题，我们会看看设计模式的用途与优点，并通过实例来了解模式是如何运作。(You will learn why to use the experience and wisdom of other developers to solve the problem, we will look at the uses and benefits of design patterns, and an example to understand the model is how it works.)