将一个复杂类的表示与其构造相分离，使得相同的构建过程能够得出不同的表示。
四个核心角色：产品、抽象建造者、具体建造者，指挥者

package com.strife.pattern.builder;

/**
 * 建造者模式
 *
 * @author mengzhenghao
 * @date 2022/5/29
 */
public class Builder {

    public static void main(String[] args) {
        AbstractHouseBuilder houseBuilder = new CommonHouseBuilder();
        HouseDirector director = new HouseDirector(houseBuilder);
        director.commandBuildHouse();
        houseBuilder = new HighBuildingBuilder();
        //重置建造者
        director.setHouseBuilder(houseBuilder);
        director.commandBuildHouse();
    }
}

/** 产品（房子）*/
class House {
    /** 地基 */
    private String basic;
    /** 墙 */
    private String wall;
    /** 房顶 */
    private String roofed;

    public String getBasic() {
        return basic;
    }

    public void setBasic(String basic) {
        this.basic = basic;
    }

    public String getWall() {
        return wall;
    }

    public void setWall(String wall) {
        this.wall = wall;
    }

    public String getRoofed() {
        return roofed;
    }

    public void setRoofed(String roofed) {
        this.roofed = roofed;
    }
}

/** 抽象建造者 */
abstract class AbstractHouseBuilder {

    /** 组合一个house */
    protected House house = new House();

    /** 打地基 */
    public abstract void buildBasic();

    /** 砌墙 */
    public abstract void buildWall();

    /** 封顶 */
    public abstract void roofed();

    public House buildHouse() {
        return house;
    }
}

/** 具体建造者（普通房子）*/
class CommonHouseBuilder extends AbstractHouseBuilder {

    @Override
    public void buildBasic() {
        System.out.println("普通房子打地基");
    }

    @Override
    public void buildWall() {
        System.out.println("普通房子砌墙");
    }

    @Override
    public void roofed() {
        System.out.println("普通房子封顶");
    }
}

/** 具体建造者（高楼） */
class HighBuildingBuilder extends AbstractHouseBuilder {

    @Override
    public void buildBasic() {
        System.out.println("高楼打地基");
    }

    @Override
    public void buildWall() {
        System.out.println("高楼砌墙");
    }

    @Override
    public void roofed() {
        System.out.println("高楼封顶");
    }
}

/** 指挥者 */
class HouseDirector {

    private AbstractHouseBuilder houseBuilder;

    public HouseDirector(AbstractHouseBuilder houseBuilder) {
        this.houseBuilder = houseBuilder;
    }

    public void setHouseBuilder(AbstractHouseBuilder houseBuilder) {
        this.houseBuilder = houseBuilder;
    }

    /** 指挥者决定如何建造房子 */
    public House commandBuildHouse() {
        houseBuilder.buildBasic();
        houseBuilder.buildWall();
        houseBuilder.roofed();
        return houseBuilder.buildHouse();
    }
}