Builder mode (builder mode)

Requirements:
1) Need to build a house: this process is piling, building walls and capping
2) There are all kinds of houses, such as ordinary houses, high-rise buildings, villas. Although the process of all kinds of houses is the same, the requirements are not the same
3) Please write a program to complete the requirements
Basic introduction
1) Builder Pattern, also known as Builder Pattern, is an object construction pattern. It can abstract the construction process of complex objects (abstract categories), so that different implementation methods of this abstract process can construct objects with different representations (attributes).
2) Builder mode is to create a complex object step by step. It allows users to build complex objects only by specifying their types and contents. Users do not need to know the specific internal construction details.

Four roles of builder model
1)Product role: a specific product object.
2)Builder (Abstract builder): create an interface / abstract class specified by each part of a Product object.
3)ConcreteBuilder: implement interfaces, build and assemble various components.
4)Director: build an object that uses the Builder interface. It is mainly used to create a complex object. It has two main functions: one is to isolate the production process of customers and objects; the other is to control the production process of product objects.

Product

package com.zhangqi.day1.builder;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

/**
 * @author: zhangqi
 * @create: 2022/1/31 19:02
 */
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
public class House implements Serializable {
    private static final long serialVersionUID = -1209427401260154692L;
    private String baise;
    private String wall;
    private String roofed;
}

Builder

package com.zhangqi.day1.builder;

/**
 * Abstract builder
 *
 * @author: zhangqi
 * @create: 2022/1/31 19:03
 */
public abstract class HouseBuilder {
    protected House house = new House();

    //Write the construction process and abstract method
    public abstract void buildBasic();

    public abstract void buildWalls();

    public abstract void roofed();

    //Build a house and return the product (house)
    public House buildHouse() {
        return house;
    }

}

ConcreteBuilder

package com.zhangqi.day1.builder;

/**
 * @author: zhangqi
 * @create: 2022/1/31 19:03
 */
public class HighBuilding extends HouseBuilder {


    @Override
    public void buildBasic() {
        System.out.println(" The foundation of the tall building is 100 meters ");
    }


    @Override
    public void buildWalls() {
        System.out.println(" Wall construction of tall buildings 20 cm ");
    }


    @Override
    public void roofed() {
        System.out.println(" Transparent roof of high-rise building ");
    }

}

Director

package com.zhangqi.day1.builder;

/**
 * @author: zhangqi
 * @create: 2022/1/31 19:04
 */
public class HouseDirector {

    HouseBuilder houseBuilder = null;

    //Constructor passed into houseBuilder
    public HouseDirector(HouseBuilder houseBuilder) {
        this.houseBuilder = houseBuilder;
    }

    //Pass in houseBuilder through setter
    public void setHouseBuilder(HouseBuilder houseBuilder) {
        this.houseBuilder = houseBuilder;
    }

    //How to deal with the process of building a house and leave it to the commander
    public House constructHouse() {
        houseBuilder.buildBasic();
        houseBuilder.buildWalls();
        houseBuilder.roofed();
        return houseBuilder.buildHouse();
    }
}

test

package com.zhangqi.day1.builder;

/**
 * @author: zhangqi
 * @create: 2022/1/31 19:04
 */
public class Client {
    public static void main(String[] args) {
        HighBuilding highBuilding = new HighBuilding();
        HouseDirector houseDirector = new HouseDirector(highBuilding);
        House house = houseDirector.constructHouse();
        System.out.println("house = " + house);
    }
}

Precautions and details of builder mode

1) The client (user program) does not need to know the details of the internal composition of the product, and decouples the product itself from the product creation process, so that the same creation process can create different product objects
2) Each specific builder is relatively independent and has nothing to do with other specific builders. Therefore, it is convenient to replace or add new specific builders. Users can get different product objects by using different specific builders
3) You can more finely control the product creation process. The creation steps of complex products are decomposed into different methods, which makes the creation process clearer and more convenient to use programs to control the creation process
4) Adding a new specific builder does not need to modify the code of the original class library. The commander class is programmed for the abstract builder class, which is convenient for system expansion and conforms to the "opening and closing principle"
5) The products created by the builder mode generally have more in common and their components are similar. If there are great differences between products, it is not suitable to use the builder mode, so its scope of use is limited.
6) If the internal changes of the product are complex, it may lead to the need to define many specific builder classes to realize this change, resulting in the system becoming very large. Therefore, in this case, it is necessary to consider whether to choose the builder mode
7) Abstract factory pattern VS builder pattern
Abstract factory mode realizes the creation of product family. A product family is a series of products: product combinations with different classification dimensions. Adopting abstract factory mode does not need to care about the construction process, but only about what products are produced by what factory. The builder model requires the product to be built according to the specified blueprint. Its main purpose is to produce a new product by assembling spare parts