設計模式四--建造者模式

一、定義

將一個複雜對象呢的構建與它的表示分離，使得同樣的構建過程可以創建不同的表示。

二、優點

封裝性

建造者獨立，容易擴展

三、原理圖

Product代表具體的產品

ConcreteBuilder是這些產品建造過程的一個介面

Builder是這些產品的具體建造實例，實現ConcreteBuilder介面

Director包含不同的Builder，負責構造各個產品

四、實例

1、Computer

抽象的電腦類

public abstract class Computer {
    private String type;//型號
    private String cpu;

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getCpu() {
        return cpu;
    }

    public void setCpu(String cpu) {
        this.cpu = cpu;
    }
    
}

2、T410

繼承了Computer類

代表T410電腦

 1 package definition;
 2 
 3 public class T410 extends Computer {
 4     private String graphicCard;//顯卡
 5     public T410(){
 6         this.setType("ThinkPad T410");
 7     }
 8     public String getGraphicCard() {
 9         return graphicCard;
10     }
11     public void setGraphicCard(String graphicCard) {
12         this.graphicCard = graphicCard;
13     }
14     
15     
16     //輸出型號，記憶體和顯卡
17     public String toString() {
18         return "T410 [getType()=" + getType() + ", getCpu()=" + getCpu() + ", graphicCard=" + graphicCard + "]";
19     }
20     
21 }

3、X201

繼承了Computer類

代表X201電腦

 1 public class X201 extends Computer {
 2 
 3     public X201() {
 4         this.setType("ThinkPad X201");
 5     }
 6 
 7     //顯示型號和cpu
 8     public String toString() {
 9         return "X201 [getType()=" + getType() + ", getCpu()=" + getCpu() + "]";
10     }
11 
12 }

4、ComputerBuilder

介面類，用於建造電腦

1 public interface ComputerBuilder {
2     void buildCpu();//建造cpu
3     void buildGraphicCard();//建造顯卡
4     
5     Computer getResult();//得到建造好的電腦
6 }

5、T410Builder

實現ComputerBuilder介面

T410的具體實現

 1 public class T410Builder implements ComputerBuilder {
 2     private T410 computer =new T410();
 3 
 4     public void buildCpu() {
 5         computer.setCpu("i5-450");
 6     }
 7     
 8     public void buildGraphicCard(){
 9         computer.setGraphicCard("Nvidia NVS 3100M");
10     }
11 
12     public Computer getResult() {
13         
14         return computer;
15     }
16 
17 }

6、X201Builder

實現ComputerBuilder介面

X201的具體實現

public class X201Builder implements ComputerBuilder {

    private X201 computer = new X201();
    public void buildCpu() {
        computer.setCpu("i3-350");
    }

    public Computer getResult() {
        return computer;
    }

    public void buildGraphicCard() {
        // TODO Auto-generated method stub
        
    }

}

7、ComputerDirector

Director包含不同的Builder，負責構造各個產品

 1 public class ComputerDirector {
 2     ComputerBuilder builder;
 3 
 4     //建造T410號機器
 5     public T410 constructT410() {
 6         builder=new T410Builder();
 7         builder.buildCpu();
 8         builder.buildGraphicCard();
 9         return (T410)builder.getResult();
10     }
11 
12     //建造X201號機器
13     public X201 constructX201() {
14         builder=new X201Builder();
15         builder.buildCpu();
16         return (X201)builder.getResult();
17     }
18 
19 }

8、ComputerTest

具體的測試類

 1 public class ComputerTest {
 2 
 3     public static void main(String[] args) {
 4         ComputerDirector computerDirector=new ComputerDirector();
 5         Computer t410=computerDirector.constructT410();
 6         System.out.println(t410);
 7         
 8         System.out.println("----------------------------");
 9         
10         Computer x201=computerDirector.constructX201();
11         System.out.println(x201);
12     }
13 
14 }

五、實驗結果

T410 [getType()=ThinkPad T410, getCpu()=i5-450, graphicCard=Nvidia NVS 3100M]

----------------------------

X201 [getType()=ThinkPad X201, getCpu()=i3-350]