设计模式 UML & java code

A: 创造性模式

1. 工厂方法模式(FactoryMethod)

1.1 类图

1.2 代码1

public interface Pet
{
    public String petSound();
}

public class Cat implements Pet {
    @Override
    public String petSound() {
        return "Meaw Meaw...";
    }
}

public class Dog implements Pet {
    @Override
    public String petSound() {
        return "Bow Bow...";
    }
}

public class PetFactory {
    public Pet getPet(String petType){
        Pet pet = null;
        if("Bow".equals(petType)){
            pet = new Dog();
        }else if("Meaw".equals(petType)){
            pet = new Cat();
        }
        return pet;
    }
}

public class SampleFactoryMethod {
    public static void main(String[] args){
        PetFactory factory = new PetFactory();
        Pet pet = factory.getPet("Bow");
        System.out.println(pet.petSound());
    }
}

代码2 (泛型)

public abstract class Product {
    public void method1(){
        //
    };
    public abstract void method2();
}

public class ConcreateProduct1 extends Product {
    @Override
    public void method2() {

    }
}

public class ConcreateProduct2 extends Product {
    @Override
    public void method2() {

    }
}

public abstract class Creator {
    public abstract <T extends Product> T createProduct(Class<T> c);
}

public class ConcreateCreator extends Creator {
    @Override
    public <T extends Product> T createProduct(Class<T> c) {
        Product instance = null;
        try {
            instance = (Product) Class.forName(c.getName()).newInstance();
        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return (T)instance;
    }
}

public class Client {
    public static void main(String[] args){
        Creator creator = new ConcreateCreator();
        ConcreateProduct1 product1 = creator.createProduct(ConcreateProduct1.class);
    }
}

2. 抽象工厂模式(AbstractFactory)

2.1 类图

2.2 代码

package org.rocky.learn.designPattern.AbstractFactory;

/**
 * Created by admin on 2018/3/20.
 */
public abstract class Car {
    public abstract Parts getWheels();
    public abstract Parts getMirrors();
    public abstract Parts getEngine();
    public abstract Parts getBody();
}

package org.rocky.learn.designPattern.AbstractFactory;

/**
 * Created by admin on 2018/3/20.
 */
public class Parts {
    private String specification;
    public Parts(String specification){
        this.specification = specification;
    }
    public String getSpecification(){
        return specification;
    }
}

package org.rocky.learn.designPattern.AbstractFactory;

/**
 * Created by admin on 2018/3/20.
 */
public class BenQ extends Car  {
    @Override
    public Parts getWheels() {
        return new Parts("BenQ Wheels");
    }

    @Override
    public Parts getMirrors() {
        return new Parts("BenQ Mirriors");
    }

    @Override
    public Parts getEngine() {
        return new Parts("BenQ Engine");
    }

    @Override
    public Parts getBody() {
        return new Parts("BenQ body");
    }
}

package org.rocky.learn.designPattern.AbstractFactory;

/**
 * Created by admin on 2018/3/20.
 */
public class BMW extends Car {
    @Override
    public Parts getWheels() {
        return new Parts("BMW Wheels");
    }

    @Override
    public Parts getMirrors() {
        return new Parts("BMW Mirrors");
    }

    @Override
    public Parts getEngine() {
        return new Parts("BMW Engine");
    }

    @Override
    public Parts getBody() {
        return new Parts("BMW Body");
    }
}

package org.rocky.learn.designPattern.AbstractFactory;

/**
 * Created by admin on 2018/3/20.
 */
public class CarType {
    private Car car;
    public Car getCar(String carType){
        if("BenQ".equals(carType)){
            car =  new BenQ();
        }else if("BMW".equals(carType)){
            car = new BMW();
        }
        return car;
    }
    public static void main(String[] args){
        CarType carType = new CarType();
        Car benQ = carType.getCar("BenQ");
        System.out.println(benQ.getWheels().getSpecification());
        System.out.println(benQ.getMirrors().getSpecification());
        System.out.println(benQ.getEngine().getSpecification());
        System.out.println(benQ.getBody().getSpecification());
    }
}

3. 建造者模式(Builder)

克隆对象分为浅层复制和深层复制

3.1 类图

3.2 代码1

public interface CarPlan {
    public void setBase(String basement);
    public void setWheels(String structure);
}

public class Car implements  CarPlan {
    private String base;
    private String wheels;
    @Override
    public void setBase(String basement) {
        this.base = basement;
    }

    @Override
    public void setWheels(String structure) {
        this.wheels = structure;
    }

    @Override
    public String toString() {
        return "Car{" +
                "base='" + base + '\'' +
                ", wheels='" + wheels + '\'' +
                '}';
    }
}

public interface CarBuilder {
    public void buildBase();
    public void buildWheels();
    public Car getCar();
}

public class LowPriceCarBuilder implements CarBuilder {
    private Car car;
    public LowPriceCarBuilder(){
        car = new Car();
    }
    @Override
    public void buildBase() {
        car.setBase("Low Price Car Base Build");
    }

    @Override
    public void buildWheels() {
        car.setWheels("Low Price Car Wheels build");
    }

    @Override
    public Car getCar() {
        return this.car;
    }
}

public class MechanicalEngineer {
    private CarBuilder carBuilder;
    public MechanicalEngineer(CarBuilder carBuilder){
        this.carBuilder = carBuilder;
    }
    public Car getCar(){
        return carBuilder.getCar();
    }
    public void buildCar(){
        carBuilder.buildBase();
        carBuilder.buildWheels();
    }

    public static void main(String[] args){
        CarBuilder lowPriceCarBuilder = new LowPriceCarBuilder();
        MechanicalEngineer mechanicalEngineer = new MechanicalEngineer(lowPriceCarBuilder);
        mechanicalEngineer.buildCar();
        Car car = mechanicalEngineer.getCar();
        System.out.print("Builder constructor car.."+car);
    }
}

java的api中 StringBuilder 和 StringBuffer是使用的生成器模式实例

代码2

public abstract  class House {
    protected Floor floor;
    protected Walls walls;
    protected Roof roof;

    public Floor getFloor() {
        return floor;
    }

    public void setFloor(Floor floor) {
        this.floor = floor;
    }

    public Walls getWalls() {
        return walls;
    }

    public void setWalls(Walls walls) {
        this.walls = walls;
    }

    public Roof getRoof() {
        return roof;
    }

    public void setRoof(Roof roof) {
        this.roof = roof;
    }
    public abstract String getRepresentation();
}

public interface Floor {
    public String getRepresentation();
}

public interface Walls {
    public String getRepresentation();
}

public interface Roof {
    public String getRepresentation();
}

package org.rocky.learn.designPattern.BuilderPattern2;

/**
 * Created by admin on 2018/3/20.
 */
public class WoodHouse extends House {
    @Override
    public String getRepresentation() {
        return "Build Wood House";
    }
}

package org.rocky.learn.designPattern.BuilderPattern2;

/**
 * Created by admin on 2018/3/20.
 */
public class WoodFloor implements Floor {
    @Override
    public String getRepresentation() {
        return "Build Wood Floor..";
    }
}

public class WoodWalls implements Walls {
    @Override
    public String getRepresentation() {
        return "Build Wood Walls";
    }
}

public class WoodRoof implements Roof {
    @Override
    public String getRepresentation() {
        return "Build Wood Roof";
    }
}

public abstract class HouseBuilder {
    protected House house;
    protected Floor floor;
    protected Walls walls;
    protected Roof roof;
    public abstract House createHouse();
    public abstract Floor createFloor();
    public abstract Walls createWalls();
    public abstract Roof createRoof();
}

public class WoodBuilder extends HouseBuilder {
    @Override
    public House createHouse() {
        house = new WoodHouse();
        return house;
    }

    @Override
    public Floor createFloor() {
        floor = new WoodFloor();
        return floor;
    }

    @Override
    public Walls createWalls() {
        walls = new WoodWalls();
        return walls;
    }

    @Override
    public Roof createRoof() {
        roof = new WoodRoof();
        return roof;
    }
}

public class HouseDirector {
    public House constructHouse(HouseBuilder houseBuilder){
        House house = houseBuilder.createHouse();
        System.out.println(house.getRepresentation());
        house.setFloor(houseBuilder.createFloor());
        System.out.println(house.getFloor().getRepresentation());
        house.setWalls(houseBuilder.createWalls());
        System.out.println(house.getWalls().getRepresentation());
        house.setRoof(houseBuilder.createRoof());
        System.out.println(house.getRoof().getRepresentation());
        return house;
    }
}

public class HouseClient {
    public static void main(String[] args){
        HouseDirector director = new HouseDirector();
        HouseBuilder houseBuilder = new WoodBuilder();
        director.constructHouse(houseBuilder);

    }
}

4. 单例模式(Singleton)

4.1 UML类图

4.2 代码1 被动实例化

package org.rocky.learn.designPattern.Singleton;

/**
 * Created by admin on 2018/3/20.
 */
public class SingletonPassive {
    private static  SingletonPassive singleton;
    private SingletonPassive(){}
    public static SingletonPassive getSingleton(){
        if(singleton == null){
            synchronized (SingletonPassive.class){
                if(singleton == null){
                    singleton = new SingletonPassive();
                }
            }
        }
        return singleton;
    }
}

代码2 主动实例化

public class SingletonProactive {
    private static SingletonProactive singleton = new SingletonProactive();
    private SingletonProactive(){}
    public static SingletonProactive getSingleton(){
        return singleton;
    }
}

5. 原型模式(prototype)

5.1 UML类图

5.2 代码

//浅拷贝
package org.rocky.learn.designPattern.PrototypePattern;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * Created by admin on 2018/3/21.
 */
public class Plan implements Cloneable {
    //计划名称
    private String name;
    //任务级别
    private int level;
    //开始时间
    private Date startdate;
    //截止时间
    private Date enddate;
    //执行人员
    private List<String> executors = new ArrayList<String>();

    @Override
    public Plan clone(){
        try {
            return (Plan) super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return null;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Date getStartdate() {
        return startdate;
    }

    public void setStartdate(Date startdate) {
        this.startdate = startdate;
    }

    public Date getEnddate() {
        return enddate;
    }

    public void setEnddate(Date enddate) {
        this.enddate = enddate;
    }

    public List<String> getExecutors() {
        return executors;
    }

    public void setExecutors(List<String> executors) {
        this.executors = executors;
    }

    public int getLevel() {
        return level;
    }

    public void setLevel(int level) {
        this.level = level;
    }

    @Override
    public String toString() {
        return "[name=" + name + ", level=" + level + ", startdate=" + startdate + ", enddate=" + enddate
                + ", executors=" + executors + "]";
    }
}

//client
package org.rocky.learn.designPattern.PrototypePattern;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by admin on 2018/3/21.
 */
public class Client {
    private static final String format = "YYYY-mm-dd";
    public static void main(String[] args) throws ParseException {
        List<String> executors = new ArrayList<String>();
        executors.add("张三");
        executors.add("李四");

        Plan plan = new Plan();
        plan.setName("重构前端登录界面");
        plan.setLevel(1);
        plan.setStartdate(new SimpleDateFormat(format).parse("2017-08-07"));
        plan.setEnddate(new SimpleDateFormat(format).parse("2017-08-07"));
        plan.setExecutors(executors);

        Plan plan2 = plan.clone();
        plan2.setName("后端接口改造");
        plan2.setLevel(2);
        plan2.setStartdate(new SimpleDateFormat(format).parse("2017-08-07"));
        plan2.setEnddate(new SimpleDateFormat(format).parse("2017-08-07"));

        System.out.println("地址是否一样？"+(plan == plan2));
        System.out.println("plan.getName() == plan2.getName() "+(plan.getName() == plan2.getName()));
        System.out.println("plan.getLevel() == plan2.getLevel() "+(plan.getLevel() == plan2.getLevel()));
        System.out.println("plan.getStartdate() == plan2.getStartdate() "+(plan.getStartdate() == plan2.getStartdate()));
        System.out.println("plan.getEnddate() == plan2.getEnddate() "+(plan.getEnddate() == plan2.getEnddate()));
        System.out.println("plan.getExecutors() == plan2.getExecutors() "+(plan.getExecutors() == plan2.getExecutors()));
        System.out.println("plan:"+plan.toString());
        System.out.println("plan2:"+plan2.toString());

        //plan任务比较重，在给plan添加一个人
        executors.add("王五");
        plan.setExecutors(executors);

        System.out.println();
        System.out.println("地址是否一样？"+(plan == plan2));
        System.out.println("plan.getName() == plan2.getName() "+(plan.getName() == plan2.getName()));
        System.out.println("plan.getLevel() == plan2.getLevel() "+(plan.getLevel() == plan2.getLevel()));
        System.out.println("plan.getStartdate() == plan2.getStartdate() "+(plan.getStartdate() == plan2.getStartdate()));
        System.out.println("plan.getEnddate() == plan2.getEnddate() "+(plan.getEnddate() == plan2.getEnddate()));
        System.out.println("plan.getExecutors() == plan2.getExecutors() "+(plan.getExecutors() == plan2.getExecutors()));
        System.out.println("plan:"+plan.toString());
        System.out.println("plan2:"+plan2.toString());
    }
}

//深拷贝 clone方法
package org.rocky.learn.designPattern.PrototypePattern;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * Created by admin on 2018/3/21.
 */
public class PlanDeeper {
    //计划名称
    private String name;
    //任务级别
    private int level;
    //开始时间
    private Date startdate;
    //截止时间
    private Date enddate;
    //执行人员
    private List<String> executors = new ArrayList<String>();

    @Override
    public Plan clone(){
        try {
            Plan plan = (Plan) super.clone();
            //引用类型的属性，需要处理
            if(this.getExecutors() != null){
                List<String> _executors = new ArrayList<String>();
                for(String s : this.getExecutors()){
                    _executors.add(s);
                }
                plan.setExecutors(_executors);
            }

            return plan;
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return null;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Date getStartdate() {
        return startdate;
    }

    public void setStartdate(Date startdate) {
        this.startdate = startdate;
    }

    public Date getEnddate() {
        return enddate;
    }

    public void setEnddate(Date enddate) {
        this.enddate = enddate;
    }

    public List<String> getExecutors() {
        return executors;
    }

    public void setExecutors(List<String> executors) {
        this.executors = executors;
    }

    public int getLevel() {
        return level;
    }

    public void setLevel(int level) {
        this.level = level;
    }

    @Override
    public String toString() {
        return "[name=" + name + ", level=" + level + ", startdate=" + startdate + ", enddate=" + enddate
                + ", executors=" + executors + "]";
    }
}

说明 见 3-2

B: 结构型模式

6.适配器模式(Adaptor)

6.1 UML类图

有两种应用适配器模式的方法

使用继承【类适配器】

使用关联【对象适配器】

6.2 代码

a: 使用继承【类适配器】

public class Plug {
    private String specification;

    protected String getInput(){
        return specification;
    }

    public Plug(){
        specification = "3-Pin";
    }
}

public interface Socket {
    public String getInput();
}

public class ExpansionAdaptor extends Plug implements Socket {
    @Override
    public String getInput() {
        String input = super.getInput();
        input += " converted to 2-Pin";
        return input;
    }
}

public class Client {
    public static void main(String[] args){
         Socket socket = new ExpansionAdaptor();
        String input = socket.getInput();
        System.out.print(input);

    }
}

b: 使用关联【对象适配器】

public class ExpansionAdapter implements Socket
{
    private Plug plug;
    public ExpansionAdapter(Plug p){
        plug = p;
    }
    @Override
    public String getInput() {
        String input = plug.getInput();
        input += " power converted to 2-Pin";
        return input;
    }
}

public static void main(String[] args){
        Socket socket = new ExpansionAdapter(new Plug());
        String input = socket.getInput();
        System.out.println(input);

    }

7. 桥接模式

7.1 UML图

7.2 代码

public interface TV {
    public void powerOn();
    public void powerOff();
    public void changeChannel(int channel);
}

public class GoogleTV implements TV {
    @Override
    public void powerOn() {

    }

    @Override
    public void powerOff() {

    }

    @Override
    public void changeChannel(int channel) {

    }
}

public class AppleTV implements TV {
    @Override
    public void powerOn() {

    }

    @Override
    public void powerOff() {

    }

    @Override
    public void changeChannel(int channel) {

    }
}

public abstract  class TVRemoteControl {
    private TV implementor;
    public void powerOn(){
        implementor.powerOn();
    }
    public void powerOff(){
        implementor.powerOff();
    }
    public void setChannel(int channel){
        implementor.changeChannel(channel);
    }
}

public class ConcreteTVRemoteControl extends TVRemoteControl {
    private int currentChannel;
    public void nextChannel(){
        currentChannel++;
        setChannel(currentChannel);
    }
    public void previousChannel(){
        currentChannel--;
        setChannel(currentChannel);
    }
}

8. 组合模式

8.1 UML类图

8.2 代码

public interface FileComponent {
    public void printName();
}

public class LeafFile implements FileComponent {
    private String fileName;
    public LeafFile(String name){
        fileName = name;
    }
    @Override
    public void printName() {
        System.out.println(fileName);
    }
}

public class Directory implements FileComponent {
    private String fileName;
    public Directory(String name){
        fileName = name;
    }
    private List files = new ArrayList();
    public void add(FileComponent component){
        files.add(component);
    }
    @Override
    public void printName() {
        System.out.println("Directory name : "+ fileName);
        for(int i=0; i< files.size(); i++){
            FileComponent component = (FileComponent) files.get(i);
            component.printName();
        }
    }
}

public class CompositeDemo {
    public static void main(String[] args){
        Directory one = new Directory("dir-1");
        Directory two = new Directory("dir-2");
        Directory three = new Directory("dir-3");

        LeafFile a = new LeafFile("file-a");
        LeafFile b = new LeafFile("file-b");
        LeafFile c = new LeafFile("file-c");
        LeafFile d = new LeafFile("file-d");

        one.add(a);
        one.add(two);
        two.add(b);
        two.add(c);
        two.add(three);
        three.add(d);
        one.printName();

    }
}

9. 装饰模式

9.1 UML类图

9.2 代码1

public interface House {
    public String makeHouse();
}

public class SimpleHouse implements House {
    @Override
    public String makeHouse() {
        return "Base House";
    }
}

public class HouseDecorator implements House {
    protected House house;
    public HouseDecorator(House house){
        this.house = house;
    }
    @Override
    public String makeHouse() {
        return house.makeHouse();
    }
}

public class ColorDecorator extends HouseDecorator {
    public ColorDecorator(House house){
        super(house);
    }

    private String addColor(){
        return " + red color";
    }

    public String makeHouse(){
        return house.makeHouse() + addColor();
    }
}

public class LightsDecorator extends HouseDecorator {
    public LightsDecorator(House house) {
        super(house);
    }

    private String addLights(){
        return " + LED lights";
    }

    public String makeHouse(){
        return house.makeHouse() + addLights();
    }
}

java API中 IO流用到装饰模式 (new BufferedReader(new FileReader("a.txt")))

代码2

public interface Coffee {
    public double getCosts();//加格
    public String getIngredients();//成分
}

public class SimpleCoffee implements Coffee {
    @Override
    public double getCosts() {
        return 1;
    }

    @Override
    public String getIngredients() {
        return "Coffee";
    }
}

public abstract class CoffeeDecorator implements Coffee {
    protected  final Coffee decoratedCoffee;
    protected String ingredientSeparator = ",";
    public CoffeeDecorator(Coffee coffee){
        decoratedCoffee = coffee;
    }

    @Override
    public double getCosts() {
        return decoratedCoffee.getCosts();
    }

    @Override
    public String getIngredients() {
        return decoratedCoffee.getIngredients();
    }
}

public class Milk extends CoffeeDecorator {
    public Milk(Coffee coffee) {
        super(coffee);
    }

    public double getCost(){
        return super.getCosts() + 0.5;
    }

    public String getIngredients(){
        return super.getIngredients() + ingredientSeparator + " Milk";
    }
}

public class Whip extends CoffeeDecorator {
    public Whip(Coffee coffee) {
        super(coffee);
    }
    public double getCosts(){
        return super.getCosts() + 0.7;
    }
    public String getIngredients(){
        return super.getIngredients() + ingredientSeparator + " Whip";
    }
}

public class Sprinkles extends CoffeeDecorator {

    public Sprinkles(Coffee coffee) {
        super(coffee);
    }
    public double getCosts(){
        return super.getCosts() + 0.2;
    }

    public String getIngredients(){
        return  super.getIngredients() + ingredientSeparator + " Sprinkles";
    }
}

public class DecoratorTest
{
    public static void main(String[] args){
        Coffee c = new SimpleCoffee();
        System.out.println("Cost:"+c.getCosts() + ",ingredients:"+ c.getIngredients());
        c = new Milk(c);
        System.out.println("Cost:"+c.getCosts() + ",ingredients:"+ c.getIngredients());
        c = new Whip(c);
        System.out.println("Cost:"+c.getCosts() + ",ingredients:"+ c.getIngredients());
        c = new Sprinkles(c);
        System.out.println("Cost:"+c.getCosts() + ",ingredients:"+ c.getIngredients());
    }
}

10. 门面模式

10.1 UML类图

10.2 代码

public class GUIMenu {
    public void drawMenuButtons(){}
}

public class GUITitleBar {
    public  void showTitleBar(String caption){}
}

public class GUIContent {
    public void showButtons(){}
    public void showTextFields(){}
    public void setDefaultValues(){}
}

public class MyGUI {
    private GUIContent guiContent;
    private GUIMenu guiMenu;
    private GUITitleBar guiTitleBar;
    public MyGUI(){
        guiContent = new GUIContent();
        guiMenu = new GUIMenu();
        guiTitleBar = new GUITitleBar();
    }
    public void drawGUI(){
        guiContent.setDefaultValues();
        guiContent.showButtons();
        guiContent.showTextFields();
        guiTitleBar.showTitleBar("My gui");
        guiMenu.drawMenuButtons();
    }
}

public class TestFacade {
    public static void main(String[] args){
        MyGUI myGUI = new MyGUI();
        myGUI.drawGUI();
    }
}

11. 代理模式

11.1 UML类图

11.2 代码

public interface Image {
    public void showImage();
}

public class RealImage implements Image {
    public RealImage(URL url){
        loadImage(url);
    }

    public void loadImage(URL url) {

    }

    @Override
    public void showImage() {

    }
}

public class ProxyImage implements Image {
    private URL url;
    public ProxyImage(URL url){
        this.url = url;
    }
    @Override
    public void showImage() {
        RealImage realImage = new RealImage(url);
        realImage.showImage();
    }
}

public class ProxyTest {
    public static void main(String[] args){
        try {
            Image image1 = new ProxyImage(new URL("http","ip","TestFloder/1.jpg"));
            Image image2 = new ProxyImage(new URL("http","ip","TestFloder/2.jpg"));
            Image image3 = new ProxyImage(new URL("http","ip","TestFloder/3.jpg"));
            image1.showImage();//被加载到内存中
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
    }
}

12. 享元模式

12.1 UML类图

对象属性分为内蕴状态 和 外蕴状态

12.2 代码

public interface MyShape {
    public void draw(Graphics g, int x, int y, int width, int height, Color color, boolean fill, String font);
}

public class MyOval implements  MyShape {
    private String label;
    public MyOval(String label){
        this.label = label;
    }
    @Override
    public void draw(Graphics oval, int x, int y, int width, int height, Color color, boolean fill, String font) {
        oval.setColor(color);
        oval.drawOval(x, y, width, height);
        oval.setFont(new Font(font, 12, 12));
        oval.drawString(label, x+(width/2), y);
        if(fill) oval.fillOval(x, y, width, height);

    }
}

public class MyRectangle implements MyShape {
    private String label;
    public MyRectangle(String label){
        this.label = label;
    }
    @Override
    public void draw(Graphics rectangle, int x, int y, int width, int height, Color color, boolean fill, String font) {
        rectangle.setColor(color);
        rectangle.drawRect(x, y, width, height);
        rectangle.setFont(new Font(font, 12, 12));
        rectangle.drawString(label, x+(width/2), y);
        if(fill) rectangle.fillRect(x, y, width, height);

    }
}

public class ShapeFactory {
    private  static final HashMap shapes = new HashMap();
    public static MyShape getShape(String label){
        MyShape concreteShape = (MyShape) shapes.get(label);
        if(concreteShape == null){
            if("R".equals(label)){
                concreteShape = new MyRectangle(label);
            }else if("O".equals(label)){
                concreteShape = new MyOval(label);
            }
        }
        return concreteShape;
    }
}

public class Client extends JFrame{
    private static final int WIDTH = 300;
    private static final int HEIGHT = 300;
    private static final String[] shapes = {"R", "O"};
    private static final Color colors[]  = {Color.blue, Color.black, Color.red};
    private static final boolean fill[] = {true, false};
    private static final String font[] = {"Arial", "Courier"};

    public Client(){
        Container contentPane = getContentPane();
        JButton startButton = new JButton("Draw Shapes");
        final JPanel panel = new JPanel();
        contentPane.add(panel, BorderLayout.CENTER);
        contentPane.add(startButton, BorderLayout.SOUTH);
        setSize(WIDTH, HEIGHT);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        startButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent event) {
                Graphics graphics = panel.getGraphics();
                MyShape shape = ShapeFactory.getShape(getRandomShape());
                shape.draw(graphics, getRandomX(), getRandomY(), getRandomWidth(), getRandomHeight(),
                        getRandomColor(), getRandomFill(), getRandomFont());

            }
        });

    }
    private String getRandomShape(){
        return shapes[(int)Math.random()*shapes.length];
    }
    private int getRandomX(){
        return (int) (Math.random()*WIDTH);
    }
    private int getRandomY(){
        return (int) (Math.random()*HEIGHT);
    }
    private int getRandomWidth(){
        return (int) (Math.random()*(getWidth()/7));
    }
    private int getRandomHeight(){
        return (int) (Math.random()*(getHeight()/7));
    }
    private Color getRandomColor(){
        return colors[(int) (Math.random()*colors.length)];
    }
    private boolean getRandomFill(){
        return fill[(int) (Math.random()*fill.length)];
    }
    private String getRandomFont(){
        return font[(int) (Math.random()*font.length)];
    }

    public static void  main(String[] args){
        Client client = new Client();
    }
}

C: 行为型模式

处理不同的对象间的通信关系

13. 职责链模式

13.1 UML类图

13.2 代码

列子： Servlet过滤器和JAVA异常处理机制

public abstract class Logger {
    public static int ERR = 3;
    public static int NOTICE = 5;
    public static int DEBUG = 7;
    protected int mask;
    //链中的下一个元素
    protected Logger next;

    public Logger setNext(Logger log){
        next = log;
        return log;
    }
    public void message(String msg, int priority){
        if(priority <= mask){
            writeMessage(msg);
        }
        if(next != null){
            next.message(msg, priority);
        }
    }
    protected abstract void writeMessage(String msg);
}

public class StdoutLogger extends Logger {
    public StdoutLogger(int mask){
        this.mask = mask;
    }
    @Override
    protected void writeMessage(String msg) {
        System.out.println("Writing to stdout:"+msg);
    }
}

public class EmailLogger extends Logger {
    public EmailLogger(int mask){
        this.mask = mask;
    }
    @Override
    protected void writeMessage(String msg) {
        System.out.println("Sending via email:"+msg);
    }
}

public class StderrLogger extends Logger {
    public StderrLogger(int mask){
        this.mask = mask;
    }
    @Override
    protected void writeMessage(String msg) {
        System.err.println("Sending to stderr:"+msg);
    }

}

public class ChainOfResponsibilityExample {
    public static void main(String[] args){
        //创建职责链
        Logger logger, logger1, logger2;
        logger = new StdoutLogger(Logger.DEBUG);
        logger1 = logger.setNext(new EmailLogger(Logger.NOTICE));
        logger2 = logger1.setNext(new StderrLogger(Logger.ERR));
        //由StdoutLogger进行处理
        logger.message("Entering function a:", Logger.DEBUG);
        //由StdoutLogger 和 EmailLogger进行处理
        logger.message("Step 1 finished", Logger.NOTICE);
        //由三个处理器一起完成
        logger.message("An error has occurred", Logger.ERR);
    }
}

14. 命令模式

14.1 UML类图

14.2 代码

public interface Command {
    void execute();
}

/**接收类*/
public class AirConditioner {
    public AirConditioner(){}
    public void start(){
        System.out.println("The airconditioner is on");
    }
    public void stop(){
        System.out.println("The airconditioner is off");
    }
}

/**调用类*/
public class Switch {
    private List<Command> commandHistory = new ArrayList<Command>();
    public Switch(){}
    public void storeAndExecute(Command command){
        this.commandHistory.add(command);
        command.execute();
    }
}

public class StartCommand implements Command {
    private AirConditioner theAirConditioner;
    public StartCommand(AirConditioner airConditioner){
        theAirConditioner = airConditioner;
    }
    @Override
    public void execute() {
        theAirConditioner.start();
    }
}

public class StopCommand implements Command {
    private AirConditioner theAirConditioner;
    public StopCommand(AirConditioner airConditioner){
        theAirConditioner = airConditioner;
    }
    @Override
    public void execute() {
        theAirConditioner.stop();
    }
}

public class PressSwitch {
    public static void main(String[] args){
        AirConditioner airConditioner = new AirConditioner();
        Command startCommand = new StartCommand(airConditioner);
        StopCommand stopCommand = new StopCommand(airConditioner);
        Switch sw = new Switch();
        sw.storeAndExecute(startCommand);
        sw.storeAndExecute(stopCommand);
    }
}

15. 解释器模式

15.1 UML类图

15.2 代码

public abstract class Expression {
    public abstract boolean interpret(String str);
}

public class TerminalExpression extends Expression {
    private String literal;
    public TerminalExpression(String str){
        literal = str;
    }
    @Override
    public boolean interpret(String str) {
        StringTokenizer st = new StringTokenizer(str);
        while (st.hasMoreTokens()){
            String s = st.nextToken();
            if(s.equals(literal)){
                return true;
            }
        }
        return false;
    }
}

public class OrExpression extends Expression {
    private Expression expression1 = null;
    private Expression expression2 = null;
    public OrExpression(Expression expression1, Expression expression2){
        this.expression1 = expression1;
        this.expression2 = expression2;
    }
    @Override
    public boolean interpret(String str) {
        return expression1.interpret(str) || expression2.interpret(str);
    }
}

public class AndExpression extends Expression {
    private Expression expression1 = null;
    private Expression expression2 = null;
    public AndExpression(Expression expression1, Expression expression2){
        this.expression1 = expression1;
        this.expression2 = expression2;
    }
    @Override
    public boolean interpret(String str) {
        return expression1.interpret(str) && expression2.interpret(str);
    }
}

public class InterpretTest {
    static Expression buildInterpretTree(){
        //字面含义
        Expression terminal1 = new TerminalExpression("Name1");
        Expression terminal2 = new TerminalExpression("Name2");
        Expression terminal3 = new TerminalExpression("Name3");
        Expression terminal4 = new TerminalExpression("Name4");
        Expression alternation1 = new OrExpression(terminal2, terminal3);
        Expression alternation2 = new OrExpression(terminal1, alternation1);
        Expression expression = new AndExpression(terminal4, alternation2);
        return expression;
    }

    public static void main(String[] args){
        String context = "Name4 Name3";
        Expression expression = buildInterpretTree();
        System.out.println(context + " is "+ expression.interpret(context));
    }
}

16. 迭代器模式

16.1 UML类图

16.2 代码

public class Item {
    String itemName;
    float itemPrice;
    public Item(String itemName, float itemPrice){
        this.itemName = itemName;
        this.itemPrice = itemPrice;
    }
    public String toString(){
        return itemName + ": "+itemPrice;
    }
}

public class Menu {
    List<Item> menuItems;
    public Menu(){
        menuItems = new ArrayList<Item>();
    }
    public void addItem(Item item){
        menuItems.add(item);
    }

    public Iterator<Item> createIterator(){
        return  new MenuIterator();
    }

    class MenuIterator implements Iterator<Item> {
        int currentIndex = 0;
        public boolean hasNext(){
            if(currentIndex >= menuItems.size())
                return false;
            else
                return true;
        }

        public Item first(){
            return menuItems.get(0);
        }

        public Item currentItem(){
            return menuItems.get(currentIndex);
        }

        public Item next(){
            return menuItems.get(currentIndex++);
        }

        public void remove(){
             menuItems.remove(--currentIndex);
        }
    }
}

public class IteratorTest {
    public static void main(String[] args){
        Item item1 = new Item("item1", 10f);
        Item item2 = new Item("item2", 20f);
        Item item3 = new Item("item3", 30f);
        Menu menu = new Menu();
        menu.addItem(item1);
        menu.addItem(item2);
        menu.addItem(item3);
        System.out.println("Displaying menu...");
        Iterator<Item> iterator = menu.createIterator();
        while (iterator.hasNext()){
            Item item = iterator.next();
            System.out.println(item);
        }
        System.out.println("Removing the last item returned.");
        iterator.remove();
        System.out.println("Displaying menu...");
        iterator = menu.createIterator();
        while (iterator.hasNext()){
            Item item = iterator.next();
            System.out.println(item);
        }
    }
}

17. 中介者模式

17.1 UML类图

例子 聊天程序-群聊

17.2 代码

public class Mediator {
    Buyer indianBuyer;
    Buyer frenchBuyer;
    AmericanSeller americanSeller;
    DollarConverter dollarConverter;
    public Mediator(){}
    public void registerIndianBuyer(Buyer indianBuyer){
        this.indianBuyer = indianBuyer;
    }
    public void registerFrenchBuyer(Buyer frenchBuyer){
        this.frenchBuyer = frenchBuyer;
    }
    public void registerAmericanSeller(AmericanSeller americanSeller){
        this.americanSeller = americanSeller;
    }
    public void registerDollarConverter(DollarConverter dollarConverter){
        this.dollarConverter = dollarConverter;
    }
    public boolean placeBid(float bid, String unitOfCurrency){
        float dollars = dollarConverter.convertCurrencyToDollars(bid, unitOfCurrency);
        return americanSeller.isBidAccepted(dollars);
    }
}

public class Buyer {
    Mediator mediator;
    String unitOfCurrency;
    public Buyer(Mediator mediator, String unitOfCurrency){
        this.mediator = mediator;
        this.unitOfCurrency = unitOfCurrency;
    }
    public boolean attemptToPurchase(float bid){
        System.out.println("Buyer attempting a bid of "+ bid + " " + unitOfCurrency);
        return  this.mediator.placeBid(bid, unitOfCurrency);
    }
}

public class IndianBuyer extends Buyer {
    public IndianBuyer(Mediator mediator) {
        super(mediator, "INR");
        this.mediator.registerIndianBuyer(this);
    }
}

public class FrenchBuyer extends Buyer {
    public FrenchBuyer(Mediator mediator) {
        super(mediator, "EURO");
        this.mediator.registerFrenchBuyer(this);
    }
}

public class AmericanSeller {
    Mediator mediator;
    float priceInDollars;
    public AmericanSeller(Mediator mediator, float priceInDollars){
        this.mediator = mediator;
        this.priceInDollars = priceInDollars;
        this.mediator.registerAmericanSeller(this);
    }
    public boolean isBidAccepted(float bidInDollars){
        if(bidInDollars >= priceInDollars){
            System.out.println("Seller accepts bid of "+ bidInDollars + " dollars\n");
            return true;
        }else{
            System.out.println("Seller rejects bid of " + bidInDollars + " dollars\n");
            return false;
        }
    }
}

public class DollarConverter {
    Mediator mediator;
    public static final float DOLLAR_UNIT = 1.0f;
    public static final float EURO_UNIT = 0.7f;
    public static final float INR_UNIT = 45.0f;
    public DollarConverter(Mediator mediator){
        this.mediator = mediator;
        this.mediator.registerDollarConverter(this);
    }
    private float convertEurosToDollars(float euros){
        float dollars = euros * (DOLLAR_UNIT/EURO_UNIT);
        System.out.println("Converting "+ euros + " euros to "+ dollars + " dollars");
        return dollars;
    }

    private float convertInrToDollars(float inr){
        float dollars = inr * (DOLLAR_UNIT/INR_UNIT);
        System.out.println("Converting "+ inr + " inr to "+ dollars + " dollars");
        return dollars;
    }

    public float convertCurrencyToDollars(float amount, String unitOfCurrency){
        if("INR".equals(unitOfCurrency)){
            return convertInrToDollars(amount);
        }else
            return convertEurosToDollars(amount);
    }
}

public class MediatorTest {
    public static void main(String[] args){
        Mediator mediator = new Mediator();
        Buyer indianBuyer = new IndianBuyer(mediator);
        Buyer frenchBuyer = new FrenchBuyer(mediator);
        float sellingPriceInDollars = 10.0f;
        AmericanSeller americanSeller = new AmericanSeller(mediator, sellingPriceInDollars);
        DollarConverter dollarConverter = new DollarConverter(mediator);
        float indianBidInInr = 55.0f;
        while (!indianBuyer.attemptToPurchase(indianBidInInr)){
            indianBidInInr += 15.0f;
        }
        float frenchBidInEuros = 3.0f;
        while (!frenchBuyer.attemptToPurchase(frenchBidInEuros)){
            frenchBidInEuros += 1.5f;
        }
    }
}

18. 备忘录模式

18.1 UML类图

18.2 代码

/**
 * 备忘录需要能够保存编辑内容 这里使用state代表
 * Created by admin on 2018/3/28.
 */
public class Memento {
    private String state;
    public Memento(String stateToSave){
        state = stateToSave;
    }
    public String getSavedState(){
        return state;
    }
}

/**
 * 管理者需要处理在何时、为何对发起者进行保存和回滚
 * Created by admin on 2018/3/28.
 */
public class Caretaker {
    private List<Memento> savedState = new ArrayList<Memento>();
    public void addMememto(Memento memento){
        savedState.add(memento);
    }
    public Memento getMemento(int index){
        return savedState.get(index);
    }
}

/**
 * 发起者 也会保存不会在备忘录中保存的数据
 * Created by admin on 2018/3/28.
 */
public class Originator {
    private String state;
    public void setState(String state){
        System.out.println("Setting state to "+state);
        this.state = state;
    }
    public Memento saveToMemento(){
        System.out.println("Saving "+state+" to Memento");
        return  new Memento(state);
    }
    public void restoreFromMemento(Memento memento){
        state = memento.getSavedState();
        System.out.println("Restoring state "+state+" from Memento");
    }
}

public class MementoTest {
    public static void main(String[] args){
        Caretaker caretaker = new Caretaker();
        Originator originator = new Originator();
        originator.setState("State1");
        originator.setState("State2");
        caretaker.addMememto(originator.saveToMemento());
        originator.setState("State3");
        caretaker.addMememto(originator.saveToMemento());
        originator.restoreFromMemento(caretaker.getMemento(0));
    }
}

18.3 多个状态

package org.rocky.learn.designPattern.mementoMap;

/**
 * @Author: rocky
 * @Date: Created in 2018/5/11.
 */
public class Originator {
    private String state1;
    private String state2;
    private String state3;

    //创建一个备忘录
    public Memento createMememto(){
        return new Memento(BeanUtils.backupProp(this));
    }
    //恢复一个备忘录
    public void restoreMemento(Memento memento){
        BeanUtils.restoreProp(this, memento.getStateMap());
    }

    public String getState1() {
        return state1;
    }

    public void setState1(String state1) {
        this.state1 = state1;
    }

    public String getState2() {
        return state2;
    }

    public void setState2(String state2) {
        this.state2 = state2;
    }

    public String getState3() {
        return state3;
    }

    public void setState3(String state3) {
        this.state3 = state3;
    }

    public String toString(){
        return "state1="+state1+",state2="+state2+",state3="+state3;
    }
}

public class Memento {
    private HashMap<String, Object> stateMap;
    public Memento(HashMap<String, Object> map){
        this.stateMap = map;
    }

    public HashMap<String, Object> getStateMap() {
        return stateMap;
    }

    public void setStateMap(HashMap<String, Object> stateMap) {
        this.stateMap = stateMap;
    }
}

package org.rocky.learn.designPattern.mementoMap;

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Observer;

/**
 * @Author: rocky
 * @Date: Created in 2018/5/11.
 */
public class BeanUtils {
    //把bean的所有属性和值放入HashMap中
    public static HashMap<String, Object> backupProp(Object bean){
        HashMap<String, Object> result = new HashMap<>();
        try {
            //获得bean描述
            BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass());
            //获得属性描述
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            //遍历所有属性
            for(PropertyDescriptor propertyDescriptor : propertyDescriptors){
                //属相名称
                String fieldName = propertyDescriptor.getName();
                //读取属性的方法
                Method readMethod = propertyDescriptor.getReadMethod();
                //属性值
//                Object value2 = propertyDescriptor.getValue(fieldName);
                Object value = readMethod.invoke(bean, new Object[]{});
//                System.out.println("value2::"+value2 + ",value::"+value);
                if(!fieldName.equalsIgnoreCase("class"))
                    result.put(fieldName, value);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return result;
    }

    //把hashmap的值放入bean中
    public static void restoreProp(Object bean, HashMap<String, Object> map){

        try {
            //获得bean的描述
            BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass());
            //获取属相描述
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            // 遍历所有属性
            for (PropertyDescriptor propertyDescriptor: propertyDescriptors) {
                //属性名称
                String fieldName = propertyDescriptor.getName();
                if(map.containsKey(fieldName)){
                    //获取写入方法
                    Method writeMethod = propertyDescriptor.getWriteMethod();
                    //写入值
                    writeMethod.invoke(bean, new Object[]{map.get(fieldName)});
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

public class Caretaker {
    private Memento memento;

    public Memento getMemento() {
        return memento;
    }

    public void setMemento(Memento memento) {
        this.memento = memento;
    }
}

public class Client {
    public static void main(String[] args){
        //定义发起人
        Originator originator = new Originator();
        originator.setState1("aaa");
        originator.setState2("bbb");
        originator.setState3("ccc");
        System.out.println(originator);
        Caretaker caretaker = new Caretaker();
        caretaker.setMemento(originator.createMememto());
        originator.setState1("111");
        originator.setState2("22");
        originator.setState3("333");
        System.out.println(originator);
        originator.restoreMemento(caretaker.getMemento());
        System.out.println(originator);

    }
}

18.4 安全问题

如果创建的对象只允许自己访问，可以使用内部类实现一个空接口

public class Originator {
//内部状态
private String state = "";
public String getState() {
return state;
}
public void setState(String state) {
this.state = state;
}
//创建一个备忘录
public IMemento createMemento(){
return new Memento(this.state);
}
//恢复一个备忘录
public void restoreMemento(IMemento _memento){
this.setState(((Memento)_memento).getState());
}
//内置类
private class Memento implements IMemento{
//发起人的内部状态
private String state = "";
//构造函数传递参数
private Memento(String _state){
this.state = _state;
}
private String getState() {
return state;
}
private void setState(String state) {
this.state = state;
}
}
}

public interface IMemento {
}

public class Caretaker {
//备忘录对象
private IMemento memento;
public IMemento getMemento() {
return memento;
}
public void setMemento(IMemento memento) {
this.memento = memento;
}
}

19 观察者模式

19.1 UML类图

推模式和拉模式

19.2 代码

public interface TemperatureSubject {
    public void addObserver(TemperatureObserver temperatureObserver);
    public void removeObserver(TemperatureObserver temperatureObserver);
    public void nofify();
}

public interface TemperatureObserver {
    public void update(int temperature);
}

public class TemperatureStation implements TemperatureSubject {
    Set<TemperatureObserver> temperatureObservers;
    int temperature;
    public TemperatureStation(int temperature){
        temperatureObservers = new HashSet<TemperatureObserver>();
        this.temperature = temperature;
    }
    @Override
    public void addObserver(TemperatureObserver temperatureObserver) {
        temperatureObservers.add(temperatureObserver);
    }

    @Override
    public void removeObserver(TemperatureObserver temperatureObserver) {
        temperatureObservers.remove(temperatureObserver);
    }

    @Override
    public void nofify() {
        Iterator<TemperatureObserver> iterator = temperatureObservers.iterator();
        while (iterator.hasNext()){
            TemperatureObserver temperatureObserver = iterator.next();
            temperatureObserver.update(temperature);
        }
    }

    public void setTemperature(int newTemperature){
        System.out.println("Setting temperator to "+newTemperature);
        temperature = newTemperature;
        nofify();
    }
}

public class TemperatureCustomer1 implements TemperatureObserver {
    @Override
    public void update(int temperature) {
        System.out.println("Customer 1 found the temperature as:"+temperature);
    }
}

public class TemperatureCustomer2 implements TemperatureObserver {
    @Override
    public void update(int temperature) {
        System.out.println("Customer 2 found the temperature as:"+temperature);
    }
}

public class ObserverTest {
    public static void main(String[] args){
        TemperatureStation temperatureStation = new TemperatureStation(34);
        TemperatureCustomer1 tc1 = new TemperatureCustomer1();
        TemperatureCustomer2 tc2 = new TemperatureCustomer2();
        temperatureStation.addObserver(tc1);
        temperatureStation.addObserver(tc2);
        temperatureStation.setTemperature(37);
        temperatureStation.removeObserver(tc1);
        temperatureStation.setTemperature(40);
    }
}

20. 状态模式

20.1 UML类图

20.2 代码

public interface State {
    public void pressPlay(MusicPlayerContextInterface context);
}

public class StandbyState implements State {
    @Override
    public void pressPlay(MusicPlayerContextInterface context) {
        System.out.println("Converting Standby state to Playing state");
        context.setState(new PlayingState());
    }
}

public class PlayingState implements State {
    @Override
    public void pressPlay(MusicPlayerContextInterface context) {
        System.out.println("Converting Playing state to  Standby state");
        context.setState(new StandbyState());
    }
}

public interface MusicPlayerContextInterface {
    public void requestPlay();
    public void setState(State state);
    public State getState();
}

public class MusicPlayerContext implements MusicPlayerContextInterface {
    State state;
    public MusicPlayerContext(State state){
        this.state = state;
    }
    @Override
    public void requestPlay() {
        state.pressPlay(this);
    }

    @Override
    public void setState(State state) {
        this.state = state;
    }

    @Override
    public State getState() {
        return state;
    }
}

21. 策略模式

21.1 UML类图

21.2 代码

public interface SortInterface {
    public void sort(int[] array);
}

public class QuickSort implements SortInterface {
    @Override
    public void sort(int[] array) {
        // quick sort
        System.out.println("Sort the arrat in quicksort");
    }
}

public class BubbleSort implements SortInterface {
    @Override
    public void sort(int[] array) {
        //bubble sort
        System.out.println("Sort the arrat in bubblesort");
    }
}

public abstract class Sorter {
    private SortInterface strategy;
    public void setSorter(SortInterface strategy){
        this.strategy = strategy;
    }
    public SortInterface getSorter(){
        return strategy;
    }
    public abstract void doSort(int[] listToSort);
}

public class MySorter extends Sorter {
    @Override
    public void doSort(int[] listToSort) {
        getSorter().sort(listToSort);
    }
}

public class StrategyTest {
    public static void main(String[] args){
        int[] listToSorted = {15,12,13,16,17};
        MySorter mySorter = new MySorter();
        mySorter.setSorter(new QuickSort());
        mySorter.doSort(listToSorted);
        mySorter.setSorter(new BubbleSort());
        mySorter.doSort(listToSorted);
    }
}

21.3 策略枚举

它是一个枚举; 它是一个浓缩了的策略模式的枚举。

21.4 代码

public enum Calculator {
    ADD("+"){
        @Override
        public int exec(int a, int b) {
          return a + b;
        }
    },
    SUB("-"){
        @Override
        public int exec(int a, int b) {
            return a - b;
        }
    };
    private String symbol;
    Calculator(String symbol){
        this.symbol = symbol;
    }
    public abstract int exec(int a, int b);
}

public class Client {
    public static void main(String[] args){
        int a = 5, b=7;
        System.out.println(Calculator.ADD.exec(a,b));
        System.out.println(Calculator.SUB.exec(a,b));
    }
}

22. 模板方法模式

22.1 UML类图

22.2 代码

public abstract class Lunch {
    //模板方法
    public final void prepareLunch(){
        prepareIngredients();
        cooking();
        eating();
        cleaning();
    }

    protected abstract void cleaning();

    protected  void eating(){
        System.out.println("I am eating , please don't disturb me.");
    }

    protected abstract void cooking();

    protected abstract void prepareIngredients();

}

public class McDonaldMeal extends Lunch {
    @Override
    public void cleaning() {
        System.out.println("McDonald clean....");
    }

    @Override
    public void cooking() {
        System.out.println("McDonald cook....");
    }

    @Override
    public void prepareIngredients() {
        System.out.println("McDonald prepare..");
    }
}

public class KFCMeal extends Lunch {
    @Override
    public void cleaning() {
        System.out.println("KFC clean....");
    }

    @Override
    public void cooking() {
        System.out.println("KFC cook....");
    }

    @Override
    public void prepareIngredients() {
        System.out.println("KFC prepare....");
    }
}

public class TemplateMethodTest {
    public static void main(String[] args){
        Lunch meal1 = new McDonaldMeal();
        meal1.prepareLunch();
        Lunch meal2 = new KFCMeal();
        meal2.prepareLunch();
    }
}

23. 访问者模式

23.1 UML类图

23.2 代码

public abstract class Animal {
    public abstract void accept(Person person);
}

public class Cat extends Animal {
    @Override
    public void accept(Person person) {
        person.feed(this);
        System.out.println("喵喵喵");
    }
}

public class Dog extends Animal {
    @Override
    public void accept(Person person) {
        person.feed(this);
        System.out.println("汪汪汪");
    }
}

public abstract class Person {
    public abstract void feed(Cat cat);
    public abstract void feed(Dog dog);
}

public class Owner extends Person {
    @Override
    public void feed(Cat cat) {
        System.out.println("主人喂食猫 喜欢");
    }

    @Override
    public void feed(Dog dog) {
        System.out.println("主人喂食狗 喜欢");
    }
}

public class Someone extends Person {
    @Override
    public void feed(Cat cat) {
        System.out.println("其他人喂食猫 警惕");
    }

    @Override
    public void feed(Dog dog) {
        System.out.println("其他人喂食狗 警惕");
    }
}

public class Home {
    private List<Animal> animals = new ArrayList<>();
    public void addAnimal(Animal animal){
        animals.add(animal);
    }
    public void action(Person person){
        for (Animal anmial :
                animals) {
            anmial.accept(person);
        }
    }
}

public class VisitorTest {
    public static void main(String[] args) {
        Home owerHome = new Home();
        owerHome.addAnimal(new Dog());
        owerHome.addAnimal(new Cat());

        Owner owner = new Owner();
        owerHome.action(owner);

        Someone someone = new Someone();
        owerHome.action(someone);
    }
}

二、6大设计原则

● Single Responsibility Principle：单一职责原则
● Open Closed Principle：开闭原则
● Liskov Substitution Principle：里氏替换原则
● Law of Demeter：迪米特法则
● Interface Segregation Principle：接口隔离原则
● Dependence Inversion Principle：依赖倒置原则

三、拓展

3-1 动态代理模式

以上模式十一是静态代理。

JDK实现的动态代理, 被代理类必须实现一个接口(主要用到反射)；

public interface BookStore {
    public void addBook();
}

public class BookStoreImpl implements BookStore {
    @Override
    public void addBook() {
        System.out.println("...add a book...");
    }
}

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

/**
 * @Author: rocky
 * @Date: Created in 2018/5/7.
 */
public class BookStoreProxy implements InvocationHandler {
    private Object target;
    public BookStoreProxy(Object target){
        this.target = target;
    }

    public Object getProxy() {
        return Proxy.newProxyInstance(this.target.getClass().getClassLoader(),
                this.target.getClass().getInterfaces(), this);
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("..jdk proxy start..");
        Object result = method.invoke(target, args);
        System.out.println("..jdk proxy end..");
        return result;
    }

    public static void main(String[] args){
        BookStore bookStore = (BookStore) new BookStoreProxy(new BookStoreImpl()).getProxy();
        bookStore.addBook();

    }
}

CGLIB可以实现不需要接口也可以实现动态代理(原理是通过字节码技术为一个类创建子类，并在子类中采用方法拦截的技术拦截所有父类方法的调用)

public class SayHello {
    public void say(){
        System.out.println("hello everyone");
    }
}

import org.springframework.cglib.proxy.Enhancer;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;

/**
 * @Author: rocky
 * @Date: Created in 2018/5/7.
 */
public class CglibProxy implements MethodInterceptor {
    private Enhancer enhancer = new Enhancer();
    public Object getProxy(Class clazz){
        //设置需要创建子类的类
        enhancer.setSuperclass(clazz);
        enhancer.setCallback(this);
        //通过字节码技术动态创建子类实例
        return enhancer.create();
    }
    //实现接口MethodInterceptor接口方法
    @Override
    public Object intercept(Object o, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
        System.out.println("insert before.....");
        Object result = methodProxy.invokeSuper(o, args);
        System.out.println("insert after.....");
        return result;
    }

    public static void main(String[] args){
        CglibProxy proxy = new CglibProxy();
        SayHello sayHello = (SayHello) proxy.getProxy(SayHello.class);
        sayHello.say();
    }
}

特别是调试时，只要看到类似$Proxy0这样的结构，你就应该知道这是一个动态代理了。

3-2 浅拷贝的注意事项

内部的数组和引用对象才不拷贝，其他的原始类型比如int、long、char等都会被拷贝，
但是对于String类型，Java就希望你把它认为是基本类型，它是没有clone方法的，
处理机制也比较特殊，通过字符串池（stringpool）在需要的时候才在内存中创建新的字符串，读者在使用的时候就把String当做基本类使用即可。

四、参考书籍

设计模式之禅（第2版）秦小波著
图解设计模式 [日] 结城浩
设计模式精解及面试攻略 [印] 纳拉西姆哈·卡鲁曼希