七、Builder 建造器模式

建造者模式（Builder）： 使用多个简单的对象一步一步构建成一个复杂的对象。这种类型的设计模式属于创建型模式，提供一种创建对象的最佳方式。

应用：

　　比如坑德基的汉堡、薯条、可乐、鸡翅是不变的，但是套餐是经常变化的

　　Java 中的 StringBuilder

如何使用： 一些基本部件不变，而其组合经常变化

与工厂模式的不同：建造者关注零件的组装过程，而工厂方法模式更关注零件的创建过程

建造者组成： 产品、抽象建造者、具体建造者、指挥者 4 个要素组成

例如:

【产品】装修一套房子：沙发、灯、浴室、地板

【指挥者】 Leader 指挥工人装修

【具体的建造者】工人

public class Room {

    //沙发
    private String sofa;
    //灯
    private String light;
    //浴室
    private String bashroom;
    //地板
    private String floor;

    public String getSofa() {
        return sofa;
    }

    public void setSofa(String sofa) {
        this.sofa = sofa;
    }

    public String getLight() {
        return light;
    }

    public void setLight(String light) {
        this.light = light;
    }

    public String getBashroom() {
        return bashroom;
    }

    public void setBashroom(String bashroom) {
        this.bashroom = bashroom;
    }

    public String getFloor() {
        return floor;
    }

    public void setFloor(String floor) {
        this.floor = floor;
    }

    @Override
    public String toString() {
        return "Room{" +
                "sofa='" + sofa + '\'' +
                ", light='" + light + '\'' +
                ", bashroom='" + bashroom + '\'' +
                ", floor='" + floor + '\'' +
                '}';
    }
}

public abstract class Builder {

    //计划装修房子
    protected  Room room = new Room();
    public abstract void buildSofa();
    public abstract void buildLight();
    public abstract void buildBashRoom();
    public abstract void buildFloor();

    public Room getResult(){
        return  room;
    }

}

public class WorkerBuilder extends Builder{
    @Override
    public void buildSofa() {
        room.setSofa("香港皇家沙发");
        System.out.println("装修：香港皇家沙发");
    }

    @Override
    public void buildLight() {
        room.setLight("德州进口灯");
        System.out.println("装修：德州进口灯");
    }

    @Override
    public void buildBashRoom() {
        room.setBashroom("伊丽莎白同款浴室");
        System.out.println("装修：伊丽莎白同款浴室");
    }

    @Override
    public void buildFloor() {
        room.setFloor("天空绚烂地板");
        System.out.println("装修：天空绚烂地板");
    }
}

public class Leader {

    protected Builder builder;

    public Leader(Builder builder){
        this.builder = builder;
    }

    public Room construct(){
        builder.buildBashRoom();
        builder.buildFloor();
        builder.buildLight();
        builder.buildSofa();
        return builder.getResult();
    }
}

public class Client {
    public static void main(String []args){
        Builder builder = new WorkerBuilder();
        Leader leader = new Leader(builder);
        Room newRoom = leader.construct();
        System.out.println(newRoom);
    }
}

结果：