Design Patterns - Template Method

definition

就是定义算法骨架的方法 具体的操作:在模板中直接实现某些步骤的方法,通常这些步骤的实现算法是固定的,而且是不怎么变化的,因此就可以当作公共功能实现在模板里面。
其实写设计模式的系列笔记就是一种模板方法，每篇文章的流程（目录）都是一样的，我实现了每个部分的具体细节。

template

Template method is relatively simple, first heard the concept, I found myself one kind is called template method originally used.
Template Method TemplateMethod is to achieve in an abstract class, and this particular method which uses a number of specific processes such as PrimitiveOperation1 / PrimitiveOperation2, as long as the subclass inherits the abstract template and implement specific processes, the ability to be able to provide external template method.

Examples

abstract class Shoping {
    // 模板方法，由父类实现,可以定义为final
    public final void buyGood() {
       login();
       order();
       pay();
    }
    
    abstract void login();
    abstract void order();
    abstract void pay();
}

JingdongBuy extends Shoping {
    public void login() {
        Log.d("登录京东账号");
    }

    public void order() {
        Log.d("生成京东订单");
    }

    public void pay() {
        Log.d("使用京东白条支付");
    }
}

TaobaoBuy extends Shoping {
    public void login() {
        Log.d("登录淘宝账号");
    }

    public void order() {
        Log.d("生成淘宝订单");
    }

    public void pay() {
        Log.d("使用支付宝支付");
    }
}

advantage

Template based approach to abstract common ground between different operating dissected differences.
Seek common ground: the common ground achieved in an abstract class, different concrete realization of various subclasses reserved.

1. Reduce duplication of code, send will follow the expansion and maintenance
2. In line with the principle of opening and closing, subclasses can extend the functionality

Shortcoming

1. Increase the abstract class
2. Read the code more difficult (need to subclass looking to achieve)

Note: Abstract excessive post-expansion may cause trouble, try to ensure that the process will not change after template