101 lines
2.1 KiB
Markdown
101 lines
2.1 KiB
Markdown
## 模板方法（Template Method）
|
||
|
||
### Intent
|
||
|
||
定义算法框架，并将一些步骤的实现延迟到子类。
|
||
|
||
通过模板方法，子类可以重新定义算法的某些步骤，而不用改变算法的结构。
|
||
|
||
### Class Diagram
|
||
|
||
<div align="center"> <img src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/ac6a794b-68c0-486c-902f-8d988eee5766.png"/> </div><br>
|
||
|
||
### Implementation
|
||
|
||
冲咖啡和冲茶都有类似的流程，但是某些步骤会有点不一样，要求复用那些相同步骤的代码。
|
||
|
||
<div align="center"> <img src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/11236498-1417-46ce-a1b0-e10054256955.png"/> </div><br>
|
||
|
||
```java
|
||
public abstract class CaffeineBeverage {
|
||
|
||
final void prepareRecipe() {
|
||
boilWater();
|
||
brew();
|
||
pourInCup();
|
||
addCondiments();
|
||
}
|
||
|
||
abstract void brew();
|
||
|
||
abstract void addCondiments();
|
||
|
||
void boilWater() {
|
||
System.out.println("boilWater");
|
||
}
|
||
|
||
void pourInCup() {
|
||
System.out.println("pourInCup");
|
||
}
|
||
}
|
||
```
|
||
|
||
```java
|
||
public class Coffee extends CaffeineBeverage {
|
||
@Override
|
||
void brew() {
|
||
System.out.println("Coffee.brew");
|
||
}
|
||
|
||
@Override
|
||
void addCondiments() {
|
||
System.out.println("Coffee.addCondiments");
|
||
}
|
||
}
|
||
```
|
||
|
||
```java
|
||
public class Tea extends CaffeineBeverage {
|
||
@Override
|
||
void brew() {
|
||
System.out.println("Tea.brew");
|
||
}
|
||
|
||
@Override
|
||
void addCondiments() {
|
||
System.out.println("Tea.addCondiments");
|
||
}
|
||
}
|
||
```
|
||
|
||
```java
|
||
public class Client {
|
||
public static void main(String[] args) {
|
||
CaffeineBeverage caffeineBeverage = new Coffee();
|
||
caffeineBeverage.prepareRecipe();
|
||
System.out.println("-----------");
|
||
caffeineBeverage = new Tea();
|
||
caffeineBeverage.prepareRecipe();
|
||
}
|
||
}
|
||
```
|
||
|
||
```html
|
||
boilWater
|
||
Coffee.brew
|
||
pourInCup
|
||
Coffee.addCondiments
|
||
-----------
|
||
boilWater
|
||
Tea.brew
|
||
pourInCup
|
||
Tea.addCondiments
|
||
```
|
||
|
||
### JDK
|
||
|
||
- java.util.Collections#sort()
|
||
- java.io.InputStream#skip()
|
||
- java.io.InputStream#read()
|
||
- java.util.AbstractList#indexOf()
|