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
  [java]
1
2
3
4
5
6
7
8
9
10
11
12
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
  [java]
1
2
3
4
5
6
7
8
9
10
11
12
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
  [java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
package com.ryo.design.pattern.note.decorator;

/**
 * Created by bbhou on 2017/8/11.
 */
public interface Painter {

    /**
     * 绘制
     */
    void draw();

}
  • PainterDecorator.java
  [java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
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
  [java]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
/*
 * 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
  [plaintext]
1
2
3
4
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

装饰器模式

系列导航

系列导航