设计模式之建造者模式

建造者模式

• 建造者模式典型应用场景：包工头安排工人建一桌房子，产品需要的材料 地基，钢铁，材料

• 代码实现关键点 包工头对象、工人对象、产品对象、建造者对象：

• 有包工头指挥工人的实现代码如下

1. 建造者对象，包含材料及实现

package com.gof23.builder1.demo1;

public abstract class Builder {
    public abstract  void builderA();
    public abstract  void builderB();
    public abstract  void builderC();

    public abstract Room getRoom();
}

2. 房子对象

package com.gof23.builder1.demo1;

public class Room {
    private String builderA ;

    public String getBuilderA() {
        return builderA;
    }

    public void setBuilderA(String builderA) {
        this.builderA = builderA;
    }

    public String getBuilderB() {
        return builderB;
    }

    public void setBuilderB(String builderB) {
        this.builderB = builderB;
    }

    public String getBuilderC() {
        return builderC;
    }

    public void setBuilderC(String builderC) {
        this.builderC = builderC;
    }

    private String builderB;
    private String builderC;

    @Override
    public String toString() {
        return "Room{" +
                "builderA=‘" + builderA + ‘\‘‘ +
                ", builderB=‘" + builderB + ‘\‘‘ +
                ", builderC=‘" + builderC + ‘\‘‘ +
                ‘}‘;
    }
}

3. 工人对象

package com.gof23.builder1.demo1;

public class Worker extends Builder {
    private Room room;

    public Worker(){
        this.room = new Room();
    }
    @Override
    public void builderA() {
        this.room.setBuilderA("A");
    }

    @Override
    public void builderB() {
        this.room.setBuilderB("M");
    }

    @Override
    public void builderC() {
        this.room.setBuilderC("C");
    }


    public Room getRoom() {
        return room;
    }
}

4. 包工头对象

package com.gof23.builder1.demo1;

public class Directory {
    public Room builder(Builder builder){
        builder.builderB();
        builder.builderA();
        builder.builderC();

        return builder.getRoom();
    }
}

5. client测试实现包工头指挥工人造房子

package com.gof23.builder1.demo1;

public class Client {
    public static void main(String[] args) {
        Directory directory = new Directory();
        Room room = directory.builder(new Worker());
        System.out.println(room.toString());
    }
}

• 无包工头，老板或者客户直接指挥工人造房子实现代码如下

1. 建造者对象，包含材料及实现

package com.gof23.builder1.demo1;

public abstract class Builder {
    public abstract  Builder builderA(String msg);
    public abstract  Builder builderB(String msg);
    public abstract  Builder builderC(String msg);

    public abstract Room getRoom();
}

2. 房子对象

package com.gof23.builder1.demo1;

public class Room {
    private String builderA ;

    public String getBuilderA() {
        return builderA;
    }

    public void setBuilderA(String builderA) {
        this.builderA = builderA;
    }

    public String getBuilderB() {
        return builderB;
    }

    public void setBuilderB(String builderB) {
        this.builderB = builderB;
    }

    public String getBuilderC() {
        return builderC;
    }

    public void setBuilderC(String builderC) {
        this.builderC = builderC;
    }

    private String builderB;
    private String builderC;

    @Override
    public String toString() {
        return "Room{" +
                "builderA=‘" + builderA + ‘\‘‘ +
                ", builderB=‘" + builderB + ‘\‘‘ +
                ", builderC=‘" + builderC + ‘\‘‘ +
                ‘}‘;
    }
}

3. 工人对象

package com.gof23.builder1.demo2;

public class Worker extends Builder {
    private Room room;

    public Worker(){
        this.room = new Room();
    }
    @Override
    public Builder builderA(String msg) {
        this.room.setBuilderA(msg);
        return this;
    }

    @Override
    public Builder builderB(String msg) {
        this.room.setBuilderB(msg);
        return this;
    }

    @Override
    public Builder builderC(String msg) {
        this.room.setBuilderC(msg);
        return this;
    }


    public Room getRoom() {
        return room;
    }
}

4. client测试模拟实现直接指挥工人造房子，这种方式更灵活，建房子的材料及步骤都可控制

package com.gof23.builder1.demo2;

public class Client {
    public static void main(String[] args) {
        Room room = new Worker().builderA("水泥地").builderC("MMM").builderB("sdfsdfsdf").getRoom();
        System.out.println(room.toString());
    }
}

小结: 1. 建造者模式应用比较框，底层框架用的也比较多
2. 实现指挥者的建造者模式相对无实现指挥者的建造者模式更笨拙点，只能由具体的指挥者或包工头来定义建房子的材料及步骤，而无实现具体指挥者的，client测试模拟实现直接指挥工人造房子，这种方式更灵活，建房子的材料及步骤都可控制
推荐方式2

原文：https://www.cnblogs.com/lwdesire/p/15350330.html