参考：Java常见设计模式总结
概念
概念理解一：将复杂对象的创建过程分解在不同的方法中，不同的创建过程组装成不同对象。对象的创建与产品本身分离开，使得对象的创建过程更加清晰。例如：旅游套餐售卖场景。
一个套餐大概会由机票、车票、酒店、景点门票组成。
套餐A: 机票1 + 酒店1 + 景点门票1
套餐B: 车票1 + 景点门票2
套餐C: 机票1 + 酒店1
等等
概念理解二：如果对象的构造的入参十分复杂时，构造对象需要转为链式写法时
第三方库举例：
1、由于产品的构造函数参数太多或者组合方式太多
Mybaitis 和 SqlSessionFactoryBuilder
2、将 set 方法转成链式写法
StringBuilder,StringBuffer.append()方法
抽象建造者 Builder：相当于建筑蓝图，声明了创建 Product 对象的各个部件指定的抽象接口。
具体建造者 ConcreteBuilder：实现Builder抽象接口，构建和装配各个部件，定义并明确它所创建的表示，并提供一个检索产品的接口。
指挥者 Director：构建一个使用 Builder 接口的对象。主要有两个作用，一是隔离用户与对象的生产过程，二是负责控制产品对象的生产过程。
产品角色 Product：被构造的复杂对象。ConcreteBuilder 创建该产品的内部表示并定义它的装配过程，包含定义组成部件的类，包括将这些部件装配成最终产品的接口。
抽象构造者
@Data
public abstract class Builder {Package pack = new Package();public abstract void buildAirTicket();public abstract void buildHotel();public abstract void buildTripTicket();public abstract void buildCarTicket();public Package getPack(){return pack;}
}
套餐A具体的构造者 PackageAConcreteBuilder
@Data
public class PackageAConcreteBuilder extends Builder {
// 套餐A: 机票1 + 酒店1 + 景点门票1@Overridepublic void buildAirTicket() {AirTicket airTicket1 = new AirTicket(1000, 999, "机票1", "0001", 200);pack.setAirTicket(airTicket1);}@Overridepublic void buildHotel() {Hotel hotel1 = new Hotel(300, 999, "酒店1", 2);pack.setHotel(hotel1);}@Overridepublic void buildTripTicket() {TripTicket tripTicket1 = new TripTicket(50, 9999, "景点门票1");pack.setTripTicket(tripTicket1);}@Overridepublic void buildCarTicket() {return;}@Overridepublic Package getPack() {return super.getPack();}
}
套餐B具体的构造者 PackageBConcreteBuilder
@Data
public class PackageBConcreteBuilder extends Builder{
// 套餐B: 车票1 + 景点门票2@Overridepublic void buildAirTicket() {}@Overridepublic void buildHotel() {}@Overridepublic void buildTripTicket() {TripTicket tripTicket2 = new TripTicket(30, 9999, "景点门票2");pack.setTripTicket(tripTicket2);}@Overridepublic void buildCarTicket() {CarTicket carTicket1 = new CarTicket(50, 9999, "车票1","0876");pack.setCarTicket(carTicket1);}@Overridepublic Package getPack() {return super.getPack();}
}
套餐模型对象类 Package 相当于图中的 Product
@Data
public class Package {AirTicket airTicket;Hotel hotel;TripTicket tripTicket;CarTicket carTicket;public Package() {}public Package(AirTicket airTicket, Hotel hotel, TripTicket tripTicket, CarTicket carTicket) {this.airTicket = airTicket;this.hotel = hotel;this.tripTicket = tripTicket;this.carTicket = carTicket;}
}
构造者
@Data
public class SystemDirector {private Builder builder;public void setBuilder(Builder builder){this.builder = builder;}public Package ConcreteBuilder(){builder.buildAirTicket();builder.buildHotel();builder.buildCarTicket();builder.buildTripTicket();return builder.getPack();}
}
如何使用
public static void main(String[] args){SystemDirector systemDirector = new SystemDirector(); // 指挥者PackageAConcreteBuilder packageABuilder = new PackageAConcreteBuilder();PackageBConcreteBuilder packageBBuilder = new PackageBConcreteBuilder();systemDirector.setBuilder(packageABuilder);// 指挥操作套餐APackage packageA = systemDirector.ConcreteBuilder();//套餐A的具体构造者创造对象 log.info("packageA,airTicket:{},hotel:{},tripTicket:{}",packageA.airTicket.getName(),packageA.hotel.getName(),packageA.tripTicket.getName());systemDirector.setBuilder(packageBBuilder);// 指挥操作套餐BPackage packageB = systemDirector.ConcreteBuilder();//套餐B的具体构造者创造对象log.info("packageB,carTicket:{},tripTicket:{}",packageB.carTicket.getName(), packageB.tripTicket.getName());}
