创建型模式-建造者模式

package per.mjn.pattern.builder;
 
// 产品对象
public class Bike {
 
    // 车架
    private String frame;
 
    // 车座
    private String seat;
 
    public String getFrame() {
        return frame;
    }
 
    public void setFrame(String frame) {
        this.frame = frame;
    }
 
    public String getSeat() {
        return seat;
    }
 
    public void setSeat(String seat) {
        this.seat = seat;
    }
 
    @Override
    public String toString() {
        return "Bike{" +
                "frame='" + frame + '\'' +
                ", seat='" + seat + '\'' +
                '}';
    }
}

package per.mjn.pattern.builder;
 
public abstract class Builder {
 
    // 声明Bike类型的变量，并进行赋值
    protected Bike bike = new Bike();
 
    // 构建车架
    public abstract void buildFrame();
 
    // 构建车座
    public abstract void buildSeat();
 
    // 构建自行车的方法
    public abstract Bike createBike();
}

package per.mjn.pattern.builder;
 
// 具体的构建者，用来构建摩拜单车对象
public class MobileBuilder extends Builder {
 
    @Override
    public void buildFrame() {
        bike.setFrame("碳纤维车架");
    }
 
    @Override
    public void buildSeat() {
        bike.setSeat("真皮车座");
    }
 
    @Override
    public Bike createBike() {
        return bike;
    }
}

package per.mjn.pattern.builder;
 
// ofo单车构建者，用来构建ofo单车
public class OfoBuilder extends Builder {
 
    @Override
    public void buildFrame() {
        bike.setFrame("铝合金车架");
    }
 
    @Override
    public void buildSeat() {
        bike.setSeat("橡胶车座");
    }
 
    @Override
    public Bike createBike() {
        return bike;
    }
}

package per.mjn.pattern.builder;
 
// 指挥者类
public class Director {
 
    // 声明builder类型的变量
    private Builder builder;
 
    public Director(Builder builder) {
        this.builder = builder;
    }
 
    // 组装自行车的功能
    public Bike construct() {
        builder.buildFrame();
        builder.buildSeat();
        return builder.createBike();
    }
}

package per.mjn.pattern.builder;
 
public class Client {
 
    public static void main(String[] args) {
        // 创建指挥者对象
        Director director = new Director(new MobileBuilder());
 
        // 让指挥者指挥装配自行车
        Bike bike = director.construct();
 
        System.out.println(bike);
    }
}

实际开发中常使用建造者模式进行对象的创建

（以链式编程的方式创建对象，实质上是静态内部类在起作用，静态内部类中的方法返回的是本身的类型）

package per.mjn.pattern.builder.demo2;
 
public class Phone {
    private String cpu;
    private String screen;
    private String memory;
    private String mainboard;
 
    // 私有构造方法
    private Phone(Builder builder) {
        this.cpu = builder.cpu;
        this.screen = builder.screen;
        this.memory = builder.memory;
        this.mainboard = builder.mainboard;
    }
 
    @Override
    public String toString() {
        return "Phone{" +
                "cpu='" + cpu + '\'' +
                ", screen='" + screen + '\'' +
                ", memory='" + memory + '\'' +
                ", mainboard='" + mainboard + '\'' +
                '}';
    }
 
    public static final class Builder {
        private String cpu;
        private String screen;
        private String memory;
        private String mainboard;
 
        public Builder cpu(String cpu) {
            this.cpu = cpu;
            return this;
        }
 
        public Builder screen(String screen) {
            this.screen = screen;
            return this;
        }
 
        public Builder memory(String memory) {
            this.memory = memory;
            return this;
        }
 
        public Builder mainboard(String mainboard) {
            this.mainboard = mainboard;
            return this;
        }
 
        // 使用构建者创建Phone对象
        public Phone build() {
            return new Phone(this);
        }
    }
}

package per.mjn.pattern.builder.demo2;
 
public class Client {
 
    public static void main(String[] args) {
        // 通过构建者对象获取手机对象
        Phone phone = new Phone.Builder()
                .cpu("intel")
                .screen("三星")
                .memory("金士顿")
                .mainboard("华硕")
                .build();
 
        System.out.println(phone);
    }
}