添加模板方法模式

23种设计模式/模板方法模式的概念及Java实现.md

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+### 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
+
+<img src="https://gitee.com/venture_git/PicGo-CloudImg/raw/master/img/20210711135849.png" alt="img" style="zoom:67%;" />
+
+### 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。
+
+<img src="https://gitee.com/venture_git/PicGo-CloudImg/raw/master/img/20210711135916.png" alt="img" style="zoom:67%;" />
+
+```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()