生成器模式(Builder)

把复杂的对象的构建与其表示分离开，以便根据程序的需要在相同的创建过程中创建不同的表示。每个生成器必须有一个相同的方法名称。

Client创建一个Director对象，指定一个build对象，配置Director。

当product需要生成时，Director通知该builder。Builder处理通知，创建product。

Client从Builder得到product。

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Builder（VehicleBuilder）

指定一个接口用来创建Product对象。

ConcreteBuilder（MotoCycleBuilde，CarBuilder，ScooterBuilder）

实现Builder接口，创建product或组装product的部件。

提供返回product接口。

Director（Shop）

使用Builder接口创建对象

Product（Vehicle）

需要被创建的复杂对象。

代码：

//Director

public class Shop{

public void Construct(VechicleBuilder vehicleBuilder){

vehicleBuilder.BuildFrame();

vehicleBuilder.BuildEngine();

vehicleBuilder.BuildWheels();

vehicleBuilder.BuildDoors();

}

}

//Builder

public abstract class VehicleBuilder{

//Fields

protected Vehicle vehicle;

//Properties

public Vehicle getVehicle{

return vehicle;

}

//methods

abstract public void BuildFrame();

abstract public void BuildEngine();

abstract public void BuildWheels();

abstract public void BuildDoors();

}

//ConcreteBuilder

public class MotorCycleBuilder extends VehicleBuilder{

public void BuildFrame(){

vehicle=new Vehicle(“MotoCycle”);

vehicle.setFrame(“MotorCycle Frame”);

}

public void BuildEngine(){

vehicle.setEngine(“500 cc”);

}

public void BuildWheels(){

vehicle.setWheels(“2”);

}

public void BuildDoors(){

vehicle.setDoors(“0”);

}

}

public class CarBuilder extends VehicleBuilder{

public void BuildFrame(){

vehicle=new Vehicle(“Car”);

vehicle.setFrame(“Car Frame”);

}

public void BuildEngine(){

vehicle.setEngine(“2500 cc”);

}

public void BuildWheels(){

vehicle.setWheels(“4”);

}

public void BuildDoors(){

vehicle.setDoors(“4”);

}

}

public class ScooterBuilder extends VehicleBuilder{

public void BuildFrame(){

vehicle=new Vehicle(“Scooter”);

vehicle.setFrame(“Scooter Frame”);

}

public void BuildEngine(){

vehicle.setEngine(“none”);

}

public void BuildWheels(){

vehicle.setWheels(“2”);

}

public void BuildDoors(){

vehicle.setDoors(“0”);

}

}

//Product

public class Vechicle{

private String type;

private String frame;

private String engine;

private String wheels;

private String doors;

public Vehicle(String type){

this.type=type;

}

public void setFrame(String frame){

this.frame=frame;

}

public void setEngine (String engine){

this.engine = engine;

}

public void setWheels (String wheels){

this.wheels = wheels;

}

public void setDoors (String doors){

this.doors= doors;

}

public void Show(){

System.out.println(“----------------------------“);

System.out.println(“Vechicle Type:” +this.type);

System.out.println(“Frame:”+this.frame);

System.out.println(“Engine:”+this.engine);

System.out.println(“#Wheels:”+this.wheels);

System.out.println(“#Doors:”+this.doors);

}

public class BuilderApp{

public static void main(String[] args){

Shop shop=new Shop();

VehicleBuilder b1=new ScooterBuilder();

VehicleBuilder b2=new CarBuilder();

VehicleBuilder b3=new MotorCycleBuilder();

shop.Construct(b1);

b1.getVehicle.Show();

shop.Construct(b2);

b2.getVehicle.Show();

shop.Construct(b3);

b3.getVehicle.Show();

Output

---------------------------
Vehicle Type: Scooter
Frame : Scooter Frame
Engine : none
#Wheels: 2
#Doors : 0

---------------------------
Vehicle Type: Car
Frame : Car Frame
Engine : 2500 cc
#Wheels: 4
#Doors : 4

---------------------------
Vehicle Type: MotorCycle
Frame : MotorCycle Frame
Engine : 500 cc
#Wheels: 2
#Doors : 0