• 第二种设计方案是根据实际需要对形状和颜色进行组合。
对于有两个变化维度（即两个变化的原因）的系统，采用方案二来进行设计系统中类的个数更少，且系统扩展更为方便。设计方案二即是桥接模式的应用。桥接模式将继承关系转换为关联关系，从而降低了类与类之间的耦合，减少了代码编写量。
1 public interface Implementor
2 {
3 public void operationImpl();
4 }
典型的抽象类代码：
1 public abstract class Abstraction
2 {
3 protected Implementor impl;
4
5 public void setImpl(Implementor impl)
6 {
7 this.impl=impl;
8 }
9
10 public abstract void operation();
11 }
典型的扩充抽象类代码：
1 public class RefinedAbstraction extends Abstraction
2 {
3 public void operation()
4 {
5 //代码
6 impl.operationImpl();
7 //代码
8 }
9 }
实例代码(JAVA):
1 //抽象类
2 public abstract class Pen
3 {
4 protected Color color;
5 public void setColor(Color color)
6 {
7 this.color=color;
8 }
9 public abstract void draw(String name);
10 }
11
12 //扩充抽象类
13 public class SmallPen extends Pen
14 {
15 public void draw(String name)
16 {
17 String penType="小号毛笔绘制";
18 this.color.bepaint(penType,name);
19 }
20 }
21
22 //扩充抽象类
23 public class MiddlePen extends Pen
24 {
25 public void draw(String name)
26 {
27 String penType="中号毛笔绘制";
28 this.color.bepaint(penType,name);
29 }
30 }
31
32 //扩充抽象类
33 public class BigPen extends Pen
34 {
35 public void draw(String name)
36 {
37 String penType="大号毛笔绘制";
38 this.color.bepaint(penType,name);
39 }
40 }
41
42 //实现类接口
43 public interface Color
44 {
45 void bepaint(String penType,String name);
46 }
47
48 //扩充实现类
49 public class Red implements Color
50 {
51 public void bepaint(String penType,String name)
52 {
53 System.out.println(penType + "红色的"+ name + ".");
54 }
55 }
56
57 //扩充实现类
58 public class Green implements Color
59 {
60 public void bepaint(String penType,String name)
61 {
62 System.out.println(penType + "绿色的"+ name + ".");
63 }
64 }
65
66 //扩充实现类
67 public class Blue implements Color
68 {
69 public void bepaint(String penType,String name)
70 {
71 System.out.println(penType + "蓝色的"+ name + ".");
72 }
73 }
74
75 //扩充实现类
76 public class White implements Color
77 {
78 public void bepaint(String penType,String name)
79 {
80 System.out.println(penType + "白色的"+ name + ".");
81 }
82 }
83
84 //扩充实现类
85 public class Black implements Color
86 {
87 public void bepaint(String penType,String name)
88 {
89 System.out.println(penType + "黑色的"+ name + ".");
90 }
91 }
92
93 //配置文件configPen.xml
94 <?xml version="1.0"?>
95 <config>
96 <className>Blue</className>
97 <className>SmallPen</className>
98 </config>
99
100 //使用java反射创建具体的颜色和画笔
101 import javax.xml.parsers.*;
102 import org.w3c.dom.*;
103 import org.xml.sax.SAXException;
104 import java.io.*;
105 public class XMLUtilPen
106 {
107 //该方法用于从XML配置文件中提取具体类类名，并返回一个实例对象
108 public static Object getBean(String args)
109 {
110 try
111 {
112 //创建文档对象
113 DocumentBuilderFactory dFactory = DocumentBuilderFactory.newInstance();
114 DocumentBuilder builder = dFactory.newDocumentBuilder();
115 Document doc;
116 doc = builder.parse(new File("configPen.xml"));
117 NodeList nl=null;
118 Node classNode=null;
119 String cName=null;
120 nl = doc.getElementsByTagName("className");
121
122 if(args.equals("color"))
123 {
124 //获取包含类名的文本节点
125 classNode=nl.item(0).getFirstChild();
126
127 }
128 else if(args.equals("pen"))
129 {
130 //获取包含类名的文本节点
131 classNode=nl.item(1).getFirstChild();
132 }
133
134 cName=classNode.getNodeValue();
135 //通过类名生成实例对象并将其返回
136 Class c=Class.forName(cName);
137 Object obj=c.newInstance();
138 return obj;
139 }
140 catch(Exception e)
141 {
142 e.printStackTrace();
143 return null;
144 }
145 }
146 }
147
148 //客户端
149 public class Client
150 {
151 public static void main(String a[])
152 {
153 Color color;
154 Pen pen;
155
156 color=(Color)XMLUtilPen.getBean("color");
157 pen=(Pen)XMLUtilPen.getBean("pen");
158
159 pen.setColor(color);
160 pen.draw("鲜花");
161 }
162 }
原文：https://www.cnblogs.com/guohai-stronger/p/11883743.html