[设计模式Java实现附plantuml源码~创建型] 复杂对象的组装与创建——建造者模式

@startuml

class Product {
  - partA
  - partB
  - partC

}

abstract class Builder {
  + buildPartA()
  + buildPartB()
  + buildPartC()
  + getResult(): Product
}

class Director {
- builder
+ construct()
}
note left of Director::"construct()"
  builder.buildPartA();
  builder.buildPartB();
  builder.buildPartC()
  return builder.getResult();
end note

Director *-> Builder: 指挥者跟builder属于组合关系

class concreteBuilder extends Builder {
  + buildPartA()
  + buildPartB()
  + buildPartC()
  + getResult(): Product
}

concreteBuilder .left..> Product : 具体建造者生产对象



@enduml

package create;

// 使用示例
public class BuilderDemo {
    public static void main(String[] args) {
        Car car = new CarBuilder()
            .setBrand("Toyota")
            .setModel("Camry")
            .setYear(2022)
            .setHorsepower(203)
            .build();

        System.out.println(car);
    }
}

// 产品类
class Car {
    private final String brand;
    private final String model;
    private final int year;
    private final int horsepower;

    public Car(String brand, String model, int year, int horsepower) {
        this.brand = brand;
        this.model = model;
        this.year = year;
        this.horsepower = horsepower;
    }

    // Getters
    // ...

    @Override
    public String toString() {
        return "Car [brand=" + brand + ", model=" + model + ", year=" + year + ", horsepower=" + horsepower + "]";
    }
}

// 建造者类
class CarBuilder {
    private String brand;
    private String model;
    private Integer year;
    private Integer horsepower;

    public CarBuilder setBrand(String brand) {
        this.brand = brand;
        return this;
    }

    public CarBuilder setModel(String model) {
        this.model = model;
        return this;
    }

    public CarBuilder setYear(int year) {
        this.year = year;
        return this;
    }

    public CarBuilder setHorsepower(int horsepower) {
        this.horsepower = horsepower;
        return this;
    }

    public Car build() {
        if (brand == null || model == null || year == null || horsepower == null) {
            throw new RuntimeException("没有完全建造产品");
        }
        return new Car(brand, model, year, horsepower);
    }
}