建造者模式

发表于 更新于 分类于 ，
本文字数： 2k 阅读时长 ≈ 2 分钟

建造者模式(Builder Pattern)，将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示。

Class Diagram

Implementation

具体产品

1
2
3
4
5
6
7
8
9
10
11
12
public class Computer {
    List<String> components = new ArrayList<String>();

    public void add(String component){
        components.add(component);
    }

    public void display(){
        System.out.println("个人电脑，组成如下:\n--------------");
        components.forEach((System.out::println));
    }
}

建造者抽象类

1
2
3
4
5
6
abstract class Builder {
    public abstract void buildCPU();
    public abstract void buildGPU();
    public abstract void buildPower();
    public abstract Computer build();
}

具体建造者

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
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
public class StandardComputer extends Builder {

    private Computer computer = new Computer();

    @Override
    public void buildCPU() {
        computer.add("处理器");
    }

    @Override
    public void buildGPU() {
        computer.add("显卡");
    }

    @Override
    public void buildPower() {
        computer.add("电源");
    }

    @Override
    public Computer build() {
        return computer;
    }
}

public class MyComputer extends Builder{

    private Computer computer = new Computer();

    @Override
    public void buildCPU() {
        computer.add("AMD 2600x");
    }

    @Override
    public void buildGPU() {
        computer.add("GTX 2060");
    }

    @Override
    public void buildPower() {
        computer.add("爱国者 1250w");
    }

    @Override
    public Computer build() {
        return computer;
    }
}

指挥者

1
2
3
4
5
6
7
8
public class Director {

    public void construct(Builder builder){
        builder.buildCPU();
        builder.buildGPU();
        builder.buildPower();
    }
}

测试

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
public class BuilderTest {

    @Test
    public void test() throws Exception{
        Director director = new Director();

        Builder standardBuilder = new StandardComputer();
        Builder myBuilder = new MyComputer();

        director.construct(standardBuilder);
        Computer standardComputer = standardBuilder.build();
        standardComputer.display();

        director.construct(myBuilder);
        Computer myComputer = myBuilder.build();
        myComputer.display();
    }
}

Example

Refence