設計模式——建造者模式

1- 建造者模式的定義

建造者模式：使用多個簡單的對象一步一步構建成一個複雜的對象，將複雜對象的構建與表示相分離，使得同樣的構建過程可以創建不同的表示。

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2- 建造者模式的具體代碼實現

2-1複雜對象

爲了更好的瞭解建造者模式，假設有一個複雜的對象Rocket，代碼如下

package designPattern.test.builder.vo;

import java.io.Serializable;

/**
 * 需要建造的複雜的對象：火箭
 */
public abstract class Rocket implements Serializable{

    //多個助推器
    private Assistor[] assistors;

    //發動機
    private Engine engine;

    //整流罩
    private Fairing fairing;

    //火箭控制系統
    private ControlSystem controlSystem;

    public Assistor[] getAssistors() {
        return assistors;
    }

    public void setAssistors(Assistor[] assistors) {
        this.assistors = assistors;
    }

    public Engine getEngine() {
        return engine;
    }

    public void setEngine(Engine engine) {
        this.engine = engine;
    }

    public Fairing getFairing() {
        return fairing;
    }

    public void setFairing(Fairing fairing) {
        this.fairing = fairing;
    }

    public ControlSystem getControlSystem() {
        return controlSystem;
    }

    public void setControlSystem(ControlSystem controlSystem) {
        this.controlSystem = controlSystem;
    }

    //火箭發射方法
    public abstract void launch();

}

Rocket對象是由一個Assistor數組、一個Engine對象、一個Fairing對象以及一個ControlSystem對象組成，這4個部件的具體定義如下

Assistor：

package designPattern.test.builder.vo;

import java.io.Serializable;

/**
 * 助推器類：建造Rocket的部件
 */
public class Assistor implements Serializable{

    //直徑
    private double diameter;

    //高度
    private double height;

    //推力大小
    private double force;

    public double getDiameter() {
        return diameter;
    }

    public void setDiameter(double diameter) {
        this.diameter = diameter;
    }

    public double getHeight() {
        return height;
    }

    public void setHeight(double height) {
        this.height = height;
    }

    public double getForce() {
        return force;
    }

    public void setForce(double force) {
        this.force = force;
    }
}

Engine：

package designPattern.test.builder.vo;

import java.io.Serializable;

/**
 * 火箭發動機：Rocket的組成部件
 */
public class Engine implements Serializable{

    //材料
    private String material;

    //長
    private double length;

    //寬
    private double width;

    //高
    private double height;

    //重量
    private double weight;

    //動力
    private double power;

    public String getMaterial() {
        return material;
    }

    public void setMaterial(String material) {
        this.material = material;
    }

    public double getLength() {
        return length;
    }

    public void setLength(double length) {
        this.length = length;
    }

    public double getWidth() {
        return width;
    }

    public void setWidth(double width) {
        this.width = width;
    }

    public double getHeight() {
        return height;
    }

    public void setHeight(double height) {
        this.height = height;
    }

    public double getWeight() {
        return weight;
    }

    public void setWeight(double weight) {
        this.weight = weight;
    }

    public double getPower() {
        return power;
    }

    public void setPower(double power) {
        this.power = power;
    }
}

Fairing：

package designPattern.test.builder.vo;

import java.io.Serializable;

/**
 * 整流罩：構建Rocket的組成部件
 */
public class Fairing implements Serializable {

    //材質
    private String material;

    //燃點
    private double firePoint;

    //直徑
    private double diameter;

    //顏色
    private String color;

    //重量
    private double weight;

    public String getMaterial() {
        return material;
    }

    public void setMaterial(String material) {
        this.material = material;
    }

    public double getFirePoint() {
        return firePoint;
    }

    public void setFirePoint(double firePoint) {
        this.firePoint = firePoint;
    }

    public double getDiameter() {
        return diameter;
    }

    public void setDiameter(double diameter) {
        this.diameter = diameter;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }

    public double getWeight() {
        return weight;
    }

    public void setWeight(double weight) {
        this.weight = weight;
    }
}

ControlSystem

package designPattern.test.builder.vo;

import java.io.Serializable;

/**
 * 控制系統：Rocket的組成部件
 */
public class ControlSystem implements Serializable {

    //穩定性
    private double stability;

    //快速性
    private double speedability;

    //正確性
    private double validity;

    public double getStability() {
        return stability;
    }

    public void setStability(double stability) {
        this.stability = stability;
    }

    public double getSpeedability() {
        return speedability;
    }

    public void setSpeedability(double speedability) {
        this.speedability = speedability;
    }

    public double getValidity() {
        return validity;
    }

    public void setValidity(double validity) {
        this.validity = validity;
    }
}

具體的產品——SpaceXFalconHeavy

package designPattern.test.builder.vo;

/**
 * 具體的產品：重型獵鷹
 */
public class SpaceXFalconHeavy extends Rocket {

    @Override
    public void launch() {
        System.out.println("SpaceX重性獵鷹發射....");
    }

}

具體的產品——ChangZheng5

package designPattern.test.builder.vo;

/**
 * 具體的產品：長征5號
 */
public class ChangZheng5 extends Rocket {

    @Override
    public void launch() {
       System.out.println("5 4 3 2 1 長征5號發射成功！鼓掌....");
    }

}

2-2Builder接口

package designPattern.test.builder.interf;

import designPattern.test.builder.vo.*;

/**
 * Builder接口
 */
public interface RocketBuilder {

    Assistor[] buildAssistors();

    Engine buildEngine();

    Fairing buildFairing();

    ControlSystem buildControlSystem();

    Rocket getRocket();

}

RocketBuilder接口定義了Rocket複雜對象各個部件的構造過程，最後通過getRocket()方法獲取構造的複雜對象。

2-3具體對象的Builder類

SpaceXFalconHeavyBuilder

package designPattern.test.builder.interf.impl;

import designPattern.test.builder.interf.RocketBuilder;
import designPattern.test.builder.vo.*;

/**
 * RocketBuilder具體的實現類
 */
public class SpaceXFalconHeavyBuilder implements RocketBuilder {

    //構建助推器
    @Override
    public Assistor[] buildAssistors() {
        Assistor[] assistors = new Assistor[2];
        Assistor assistor = new Assistor();
        assistor.setDiameter(3.6);
        assistor.setHeight(36.0);
        assistor.setForce(15600.0);
        assistors[0] = assistor;
        assistors[1] = assistor;
        return assistors;
    }

    //構建發動機
    @Override
    public Engine buildEngine() {
        Engine engine = new Engine();
        engine.setLength(5.6);
        engine.setHeight(3.2);
        engine.setWidth(4.2);
        engine.setMaterial("合金");
        engine.setWeight(13.8);
        engine.setPower(168000.0);
        return engine;
    }

    //構建整流罩
    @Override
    public Fairing buildFairing() {
        Fairing fairing = new Fairing();
        fairing.setDiameter(5.6);
        fairing.setFirePoint(2000.0);
        fairing.setWeight(12.8);
        fairing.setColor("white");
        fairing.setMaterial("高強度碳纖維");
        return fairing;
    }

    //構建控制系統
    @Override
    public ControlSystem buildControlSystem() {
        ControlSystem controlSystem = new ControlSystem();
        controlSystem.setStability(0.98);
        controlSystem.setSpeedability(0.002);
        controlSystem.setValidity(0.999);
        return controlSystem;
    }

    //獲取產品
    @Override
    public Rocket getRocket() {
        Rocket rocket = new SpaceXFalconHeavy();
        rocket.setAssistors(buildAssistors());
        rocket.setEngine(buildEngine());
        rocket.setFairing(buildFairing());
        rocket.setControlSystem(buildControlSystem());
        return rocket;
    }

}

ChangZheng5Builder

package designPattern.test.builder.interf.impl;

import designPattern.test.builder.interf.RocketBuilder;
import designPattern.test.builder.vo.*;

/**
 * 長征5號：中國長征家族重型火箭
 */
public class ChangZheng5Builder implements RocketBuilder {

    //構建助推器
    @Override
    public Assistor[] buildAssistors() {
        Assistor[] assistors = new Assistor[4];
        Assistor assistor = new Assistor();
        assistor.setDiameter(2.8);
        assistor.setHeight(26.8);
        assistor.setForce(12800.0);
        assistors[0] = assistor;
        assistors[1] = assistor;
        assistors[2] = assistor;
        assistors[3] = assistor;
        return assistors;
    }

    //構建發動機
    @Override
    public Engine buildEngine() {
        Engine engine = new Engine();
        engine.setMaterial("耐高溫合金");
        engine.setWeight(10.8);
        engine.setPower(108000.0);
        engine.setLength(4.6);
        engine.setHeight(2.8);
        engine.setWidth(2.8);
        return engine;
    }

    //構建整流罩
    @Override
    public Fairing buildFairing() {
        Fairing fairing = new Fairing();
        fairing.setDiameter(4.9);
        fairing.setFirePoint(1500.0);
        fairing.setWeight(10.8);
        fairing.setColor("white");
        fairing.setMaterial("高溫陶瓷");
        return fairing;
    }

    //構建控制系統
    @Override
    public ControlSystem buildControlSystem() {
        ControlSystem controlSystem = new ControlSystem();
        controlSystem.setStability(0.95);
        controlSystem.setSpeedability(0.005);
        controlSystem.setValidity(0.99);
        return controlSystem;
    }

    //獲取產品
    @Override
    public Rocket getRocket() {
        Rocket rocket = new ChangZheng5();
        rocket.setAssistors(buildAssistors());
        rocket.setEngine(buildEngine());
        rocket.setFairing(buildFairing());
        rocket.setControlSystem(buildControlSystem());
        return rocket;
    }

}

3- 測試代碼

package designPattern.test.builder;

import designPattern.test.builder.interf.RocketBuilder;
import designPattern.test.builder.interf.impl.ChangZheng5Builder;
import designPattern.test.builder.interf.impl.SpaceXFalconHeavyBuilder;
import designPattern.test.builder.vo.Rocket;
import org.junit.Test;

/**
 * Builder模式測試
 */
public class BuilderTest {

    @Test
    public void testBuilder(){
        RocketBuilder builder = new SpaceXFalconHeavyBuilder();
        Rocket rocket = builder.getRocket();
        rocket.launch();
        RocketBuilder builder1 = new ChangZheng5Builder();
        Rocket rocket1 = builder1.getRocket();
        rocket1.launch();
    }

}

綜上：從測試代碼可以看出，Builder模式將複雜對象的構造和表示相分離了，假設沒有采用Builder模式，那麼SpaceXFalconHeavy和ChangZheng5的構建過程將是非常繁雜的一堆new對象並set的過程，不美觀且容易出錯！Builder模式可以很好的解決這個問題！

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設計模式——建造者模式

設計模式——建造者模式

1- 建造者模式的定義

2- 建造者模式的具體代碼實現

2-1複雜對象

2-2Builder接口

2-3具體對象的Builder類

3- 測試代碼

設計模式——模板模式

設計模式——代理模式

設計模式——工廠模式

設計模式——裝飾器模式

設計模式——適配器模式

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