装饰器模式
装饰器模式（Decorator Pattern）允许向一个现有的对象添加新的功能，同时又不改变其结构。
这种类型的设计模式属于结构型模式，它是作为现有的类的一个包装。
这种模式创建了一个装饰类，用来包装原有的类，并在保持类方法签名完整性的前提下，提供了额外的功能。
实际案例
类信息概览：
| 类名 | 说明 |
|---|---|
| Main.java | 方法的总入口 |
| RectanglePainter.java | 长方形绘图 |
| CirclePainter.java | 圆形绘图 |
| Painter.java | 绘图接口 |
| PainterDecorator.java | 绘图装饰器 |
定义
- RectanglePainter.java
package com.ryo.design.pattern.note.decorator;
/**
* Created by bbhou on 2017/8/11.
*/
public class RectanglePainter implements Painter {
@Override
public void draw() {
System.out.println("Draw rectangle...");
}
}
- CirclePainter.java
package com.ryo.design.pattern.note.decorator;
/**
* Created by bbhou on 2017/8/11.
*/
public class CirclePainter implements Painter {
@Override
public void draw() {
System.out.println("Draw circle...");
}
}
- Painter.java
package com.ryo.design.pattern.note.decorator;
/**
* Created by bbhou on 2017/8/11.
*/
public interface Painter {
/**
* 绘制
*/
void draw();
}
- PainterDecorator.java
package com.ryo.design.pattern.note.decorator;
/**
* Created by bbhou on 2017/8/11.
*/
public class PainterDecorator implements Painter {
private Painter painter;
public PainterDecorator(Painter painter) {
this.painter = painter;
}
@Override
public void draw() {
painter.draw();
setBorderColor();
}
private void setBorderColor() {
System.out.println("Set border color...");
}
}
测试
- Main.java
/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
* Copyright (c) 2012-2018. houbinbini Inc.
* design-pattern All rights reserved.
*/
package com.ryo.design.pattern.note.decorator;
/**
* <p> </p>
*
* <pre> Created: 2018/5/16 下午8:16 </pre>
* <pre> Project: design-pattern </pre>
*
* @author houbinbin
* @version 1.0
* @since JDK 1.7
*/
public class Main {
public static void main(String[] args) {
Painter painter = new PainterDecorator(new CirclePainter());
painter.draw();
Painter painter2 = new PainterDecorator(new RectanglePainter());
painter2.draw();
}
}
- 测试结果
Draw circle...
Set border color...
Draw rectangle...
Set border color...
实现方式
UML & Code
UML
UML 图示如下
Code
代码地址
