建造者（Builder）模式

描述

角色

• 产品角色（Product）：Phone
• 抽象建造者（Builder）：AbstracPhoneBuilder
• 具体建造者(Concrete Builder）：PhoneBuilder
• 创建的东西细节复杂，还必须暴露给使用者。屏蔽过程而不屏蔽细节

代码实现

@Data
public class Phone {
    private String name;
    private String cpu;
    private String price;
}

public abstract class PhoneBuilder {
    Phone phone;
    private String name;
    private String cpu;
    private String price;
    abstract PhoneBuilder price(String price);
    abstract PhoneBuilder name(String name);
    abstract PhoneBuilder cpu(String cpu);
    abstract Phone createPhone();
    abstract PhoneBuilder builder();
}

public class XiaoMiPhoneBuilder extends PhoneBuilder {
    @Override
    PhoneBuilder price(String price) {
        this.phone.setPrice(price);
        return this;
    }
    @Override
    PhoneBuilder name(String name) {
        this.phone.setName(name);
        return this;
    }
    @Override
    PhoneBuilder cpu(String cpu) {
        this.phone.setCpu(cpu);
        return this;
    }
    @Override
    Phone createPhone() {
        return phone;
    }
    @Override
    PhoneBuilder builder() {
        this.phone = new Phone();
        return this;
    }
}

测试

public class PhoneTest {
    public static void main(String[] args) {
        XiaoMiPhoneBuilder xiaoMiPhoneBuilder = new XiaoMiPhoneBuilder();
        Phone phone = xiaoMiPhoneBuilder.builder().price("1").name("2").cpu("3").createPhone();
        System.out.println(phone);
    }
}
//输出结果 Phone(name=2, cpu=3, price=1)

应用场景

什么场景用到？

• StringBuilder：append(); 给谁append呢？
• Swagger-ApiBuilder：
• 快速实现。Lombok-Builder模式 ……

编写代码的时候使用到了设计模式。类+模式

• xxxFactory
  xxxTemplate
• xxxBuilder
• xxxFacede
• ……