大家好。在我的旧主题中,我简要描述了每个模式,在本主题中,我将尝试详细展示如何使用模式。
生成式
辛格尔顿
描述:- 限制类的一个实例的创建并提供对其唯一对象的访问。类构造函数是私有的。该方法
getInstance()
仅创建该类的一个实例。
class Singleton {
private static Singleton instance = null;
private Singleton() {}
public static Singleton getInstance() {
if (instance == null) {
instance = new Singleton();
}
return instance;
}
public void setUp() {
System.out.println("setUp");
}
}
public class SingletonTest {//тест
public static void main(String[] args){
Singleton singelton = Singleton.getInstance();
singelton.setUp();
}
}
工厂
描述:- 当我们有一个具有多个子类的超类并且根据输入我们需要从子类返回一个时使用。该类不知道它应该创建什么类型的对象。根据传入数据创建对象。
class Factory {
public OS getCurrentOS(String inputos) {
OS os = null;
if (inputos.equals("windows")) {
os = new windowsOS();
} else if (inputos.equals("linux")) {
os = new linuxOS();
} else if (inputos.equals("mac")) {
os = new macOS();
}
return os;
}
}
interface OS {
void getOS();
}
class windowsOS implements OS {
public void getOS () {
System.out.println("применить для виндовс");
}
}
class linuxOS implements OS {
public void getOS () {
System.out.println("применить для линукс");
}
}
class macOS implements OS {
public void getOS () {
System.out.println("применить для мак");
}
}
public class FactoryTest {//тест
public static void main(String[] args){
String win = "linux";
Factory factory = new Factory();
OS os = factory.getCurrentOS(win);
os.getOS();
}
}
抽象工厂
描述:- 允许您从一系列可能的工厂中选择特定的工厂实现。创建一系列相关对象。易于扩展。
interface Lada {
long getLadaPrice();
}
interface Ferrari {
long getFerrariPrice();
}
interface Porshe {
long getPorshePrice();
}
interface InteAbsFactory {
Lada getLada();
Ferrari getFerrari();
Porshe getPorshe();
}
class UaLadaImpl implements Lada {// первая
public long getLadaPrice() {
return 1000;
}
}
class UaFerrariImpl implements Ferrari {
public long getFerrariPrice() {
return 3000;
}
}
class UaPorsheImpl implements Porshe {
public long getPorshePrice() {
return 2000;
}
}
class UaCarPriceAbsFactory implements InteAbsFactory {
public Lada getLada() {
return new UaLadaImpl();
}
public Ferrari getFerrari() {
return new UaFerrariImpl();
}
public Porshe getPorshe() {
return new UaPorsheImpl();
}
}// первая
class RuLadaImpl implements Lada {// вторая
public long getLadaPrice() {
return 10000;
}
}
class RuFerrariImpl implements Ferrari {
public long getFerrariPrice() {
return 30000;
}
}
class RuPorsheImpl implements Porshe {
public long getPorshePrice() {
return 20000;
}
}
class RuCarPriceAbsFactory implements InteAbsFactory {
public Lada getLada() {
return new RuLadaImpl();
}
public Ferrari getFerrari() {
return new RuFerrariImpl();
}
public Porshe getPorshe() {
return new RuPorsheImpl();
}
}// вторая
public class AbstractFactoryTest {//тест
public static void main(String[] args) {
String country = "UA";
InteAbsFactory ifactory = null;
if(country.equals("UA")) {
ifactory = new UaCarPriceAbsFactory();
} else if(country.equals("RU")) {
ifactory = new RuCarPriceAbsFactory();
}
Lada lada = ifactory.getLada();
System.out.println(lada.getLadaPrice());
}
}
建设者
描述:- 用于使用简单对象创建复杂对象。逐渐地,它从一个小而简单的对象创建一个更大的对象。允许您更改最终产品的内部表示。
class Car {
public void buildBase() {
print("Doing корпус");
}
public void buildWheels() {
print("Ставим колесо");
}
public void buildEngine(Engine engine) {
print("Ставим движок: " + engine.getEngineType());
}
private void print(String msg){
System.out.println(msg);
}
}
interface Engine {
String getEngineType();
}
class OneEngine implements Engine {
public String getEngineType() {
return "Первый двигатель";
}
}
class TwoEngine implements Engine {
public String getEngineType() {
return "Второй двигатель";
}
}
abstract class Builder {
protected Car car;
public abstract Car buildCar();
}
class OneBuilderImpl extends Builder {
public OneBuilderImpl(){
car = new Car();
}
public Car buildCar() {
car.buildBase();
car.buildWheels();
Engine engine = new OneEngine();
car.buildEngine(engine);
return car;
}
}
class TwoBuilderImpl extends Builder {
public TwoBuilderImpl(){
car = new Car();
}
public Car buildCar() {
car.buildBase();
car.buildWheels();
Engine engine = new OneEngine();
car.buildEngine(engine);
car.buildWheels();
engine = new TwoEngine();
car.buildEngine(engine);
return car;
}
}
class Build {
private Builder builder;
public Build(int i){
if(i == 1) {
builder = new OneBuilderImpl();
} else if(i == 2) {
builder = new TwoBuilderImpl();
}
}
public Car buildCar(){
return builder.buildCar();
}
}
public class BuilderTest {//тест
public static void main(String[] args) {
Build build = new Build(1);
build.buildCar();
}
}
原型
描述:- 有助于创建具有更好性能的重复对象,而不是创建新对象,而是创建现有对象的返回克隆。克隆现有对象。
interface Copyable {
Copyable copy();
}
class ComplicatedObject implements Copyable {
private Type type;
public enum Type {
ONE, TWO
}
public ComplicatedObject copy() {
ComplicatedObject complicatedobject = new ComplicatedObject();
return complicatedobject;
}
public void setType(Type type) {
this.type = type;
}
}
public class PrototypeTest {//тест
public static void main(String[] args) {
ComplicatedObject prototype = new ComplicatedObject();
ComplicatedObject clone = prototype.copy();
clone.setType(ComplicatedObject.Type.ONE);
}
}
结构性
适配器
描述:- 使用模式,我们可以组合两个不兼容的对象。两个不兼容对象之间的转换器。
class PBank {
private int balance;
public PBank() { balance = 100; }
public void getBalance() {
System.out.println("PBank balance = " + balance);
}
}
class ABank {
private int balance;
public ABank() { balance = 200; }
public void getBalance() {
System.out.println("ABank balance = " + balance);
}
}
class PBankAdapter extends PBank {
private ABank abank;
public PBankAdapter(ABank abank) {
this.abank = abank;
}
public void getBalance() {
abank.getBalance();
}
}
public class AdapterTest {//тест
public static void main(String[] args) {
PBank pbank = new PBank();
pbank.getBalance();
PBankAdapter abank = new PBankAdapter(new ABank());
abank.getBalance();
}
}
合成的
描述:- 使用单个类将多个对象分组为树结构。允许您通过一个对象使用多个类。
import java.util.ArrayList;
import java.util.List;
interface Car {
void draw(String color);
}
class SportCar implements Car {
public void draw(String color) {
System.out.println("SportCar color: " + color);
}
}
class UnknownCar implements Car {
public void draw(String color) {
System.out.println("UnknownCar color: " + color);
}
}
class Drawing implements Car {
private List<Car> cars = new ArrayList<Car>();
public void draw(String color) {
for(Car car : cars) {
car.draw(color);
}
}
public void add(Car s){
this.cars.add(s);
}
public void clear(){
System.out.println();
this.cars.clear();
}
}
public class CompositeTest {//тест
public static void main(String[] args) {
Car sportCar = new SportCar();
Car unknownCar = new UnknownCar();
Drawing drawing = new Drawing();
drawing.add(sportCar);
drawing.add(unknownCar);
drawing.draw("green");
drawing.clear();
drawing.add(sportCar);
drawing.add(unknownCar);
drawing.draw("white");
}
}
代理人
描述:- 表示可以通过拦截其他对象的调用来控制其他对象的对象。可以拦截对原始对象的调用。
interface Image {
void display();
}
class RealImage implements Image {
private String file;
public RealImage(String file){
this.file = file;
load(file);
}
private void load(String file){
System.out.println("Загрузка " + file);
}
public void display() {
System.out.println("Просмотр " + file);
}
}
class ProxyImage implements Image {
private String file;
private RealImage image;
public ProxyImage(String file){
this.file = file;
}
public void display() {
if(image == null){
image = new RealImage(file);
}
image.display();
}
}
public class ProxyTest {//тест
public static void main(String[] args) {
Image image = new ProxyImage("test.jpg");
image.display();
image.display();
}
}
蝇量级
描述:- 对象被重用,而不是创建大量相似的对象。节省内存。
class Flyweight {
private int row;
public Flyweight(int row) {
this.row = row;
System.out.println("ctor: " + this.row);
}
void report(int col) {
System.out.print(" " + row + col);
}
}
class Factory {
private Flyweight[] pool;
public Factory(int maxRows) {
pool = new Flyweight[maxRows];
}
public Flyweight getFlyweight(int row) {
if (pool[row] == null) {
pool[row] = new Flyweight(row);
}
return pool[row];
}
}
public class FlyweightTest {//тест
public static void main(String[] args) {
int rows = 5;
Factory theFactory = new Factory(rows);
for (int i = 0; i < rows; i++) {
for (int j = 0; j < rows; j++) {
theFactory.getFlyweight(i).report(j);
}
System.out.println();
}
}
}
正面
描述:- 通过将所有调用强制转换为单个对象来隐藏复杂的类系统。将对多个复杂对象的调用放入单个对象中。
interface Car {
void start();
void stop();
}
class Key implements Car {
public void start() {
System.out.println("Вставить ключи");
}
public void stop() {
System.out.println("Вытянуть ключи");
}
}
class Engine implements Car {
public void start() {
System.out.println("Запустить двигатель");
}
public void stop() {
System.out.println("Остановить двигатель");
}
}
class Facade {
private Key key;
private Engine engine;
public Facade() {
key = new Key();
engine = new Engine();
}
public void startCar() {
key.start();
engine.start();
}
public void stoptCar() {
key.stop();
engine.stop();
}
}
public class FacadeTest {//тест
public static void main(String[] args) {
Facade facade = new Facade();
facade.startCar();
System.out.println();
facade.stoptCar();
}
}
桥
描述:- 将实现和抽象分开,使得可以自由地相互更改它们。使具体类独立于接口实现类。
interface Engine {
void setEngine();
}
abstract class Car {
protected Engine engine;
public Car(Engine engine){
this.engine = engine;
}
abstract public void setEngine();
}
class SportCar extends Car {
public SportCar(Engine engine) {
super(engine);
}
public void setEngine() {
System.out.print("SportCar engine: ");
engine.setEngine();
}
}
class UnknownCar extends Car {
public UnknownCar(Engine engine) {
super(engine);
}
public void setEngine() {
System.out.print("UnknownCar engine: ");
engine.setEngine();
}
}
class SportEngine implements Engine {
public void setEngine(){
System.out.println("sport");
}
}
class UnknownEngine implements Engine {
public void setEngine(){
System.out.println("unknown");
}
}
public class BridgeTest {//тест
public static void main(String[] args) {
Car sportCar = new SportCar(new SportEngine());
sportCar.setEngine();
System.out.println();
Car unknownCar = new UnknownCar(new UnknownEngine());
unknownCar.setEngine();
}
}
装饰者
描述:- 向现有对象添加新功能而不绑定其结构。
interface Car {
void draw();
}
class SportCar implements Car {
public void draw() {
System.out.println("SportCar");
}
}
class UnknownCar implements Car {
public void draw() {
System.out.println("UnknownCar");
}
}
abstract class CarDecorator implements Car {
protected Car decorated;
public CarDecorator(Car decorated){
this.decorated = decorated;
}
public void draw(){
decorated.draw();
}
}
class BlueCarDecorator extends CarDecorator {
public BlueCarDecorator(Car decorated) {
super(decorated);
}
public void draw() {
decorated.draw();
setColor();
}
private void setColor(){
System.out.println("Color: red");
}
}
public class DecoratorTest {//тест
public static void main(String[] args) {
Car sportCar = new SportCar();
Car blueUnknownCar = new BlueCarDecorator(new UnknownCar());
sportCar.draw();
System.out.println();
blueUnknownCar.draw();
}
}
行为的
模板法
描述:- 允许您定义算法的基础,并允许子类覆盖算法的某些步骤,而不更改其整体结构。
abstract class Car {
abstract void startEngine();
abstract void stopEngine();
public final void start(){
startEngine();
stopEngine();
}
}
class OneCar extends Car {
public void startEngine() {
System.out.println("Start engine.");
}
public void stopEngine() {
System.out.println("Stop engine.");
}
}
class TwoCar extends Car {
public void startEngine() {
System.out.println("Start engine.");
}
public void stopEngine() {
System.out.println("Stop engine.");
}
}
public class TemplateTest {//тест
public static void main(String[] args) {
Car car1 = new OneCar();
car1.start();
System.out.println();
Car car2 = new TwoCar();
car2.start();
}
}
调解员
描述:- 提供一个中介类来处理不同类之间的所有通信。
class Mediator {
public static void sendMessage(User user, String msg){
System.out.println(user.getName() + ": " + msg);
}
}
class User {
private String name;
public User(String name){
this.name = name;
}
public String getName() {
return name;
}
public void sendMessage(String msg){
Mediator.sendMessage(this, msg);
}
}
public class MediatorTest {//тест
public static void main(String[] args) {
User user1 = new User("user1");
User user2 = new User("user2");
user1.sendMessage("message1");
user2.sendMessage("message2");
}
}
责任链
描述:- 允许您避免请求发送者对其接收者的严格依赖,同时请求可以由多个对象处理。
interface Payment {
void setNext(Payment payment);
void pay();
}
class VisaPayment implements Payment {
private Payment payment;
public void setNext(Payment payment) {
this.payment = payment;
}
public void pay() {
System.out.println("Visa Payment");
}
}
class PayPalPayment implements Payment {
private Payment payment;
public void setNext(Payment payment) {
this.payment = payment;
}
public void pay() {
System.out.println("PayPal Payment");
}
}
public class ChainofResponsibilityTest {//тест
public static void main(String[] args) {
Payment visaPayment = new VisaPayment();
Payment payPalPayment = new PayPalPayment();
visaPayment.setNext(payPalPayment);
visaPayment.pay();
}
}
观察者
描述:- 允许一个对象观察其他对象中发生的动作。
import java.util.ArrayList;
import java.util.List;
interface Observer {
void event(List<String> strings);
}
class University {
private List<Observer> observers = new ArrayList<Observer>();
private List<String> students = new ArrayList<String>();
public void addStudent(String name) {
students.add(name);
notifyObservers();
}
public void removeStudent(String name) {
students.remove(name);
notifyObservers();
}
public void addObserver(Observer observer){
observers.add(observer);
}
public void removeObserver(Observer observer) {
observers.remove(observer);
}
public void notifyObservers(){
for (Observer observer : observers) {
observer.event(students);
}
}
}
class Director implements Observer {
public void event(List<String> strings) {
System.out.println("The list of students has changed: " + strings);
}
}
public class ObserverTest {//тест
public static void main(String[] args) {
University university = new University();
Director director = new Director();
university.addStudent("Vaska");
university.addObserver(director);
university.addStudent("Anna");
university.removeStudent("Vaska");
}
}
战略
描述:- 定义了许多允许它们之间交互的算法。策略算法可以在程序执行期间改变。
interface Strategy {
void download(String file);
}
class DownloadWindownsStrategy implements Strategy {
public void download(String file) {
System.out.println("windows download: " + file);
}
}
class DownloadLinuxStrategy implements Strategy {
public void download(String file) {
System.out.println("linux download: " + file);
}
}
class Context {
private Strategy strategy;
public Context(Strategy strategy){
this.strategy = strategy;
}
public void download(String file){
strategy.download(file);
}
}
public class StrategyTest {//тест
public static void main(String[] args) {
Context context = new Context(new DownloadWindownsStrategy());
context.download("file.txt");
context = new Context(new DownloadLinuxStrategy());
context.download("file.txt");
}
}
命令
描述:- 允许您将各种操作封装到单独的对象中。
interface Command {
void execute();
}
class Car {
public void startEngine() {
System.out.println("запустить двигатель");
}
public void stopEngine() {
System.out.println("остановить двигатель");
}
}
class StartCar implements Command {
Car car;
public StartCar(Car car) {
this.car = car;
}
public void execute() {
car.startEngine();
}
}
class StopCar implements Command {
Car car;
public StopCar(Car car) {
this.car = car;
}
public void execute() {
car.stopEngine();
}
}
class CarInvoker {
public Command command;
public CarInvoker(Command command){
this.command = command;
}
public void execute(){
this.command.execute();
}
}
public class CommandTest {//тест
public static void main(String[] args) {
Car car = new Car();
StartCar startCar = new StartCar(car);
StopCar stopCar = new StopCar(car);
CarInvoker carInvoker = new CarInvoker(startCar);
carInvoker.execute();
}
}
状态
描述:- 允许对象根据其状态改变其行为。
interface State {
void doAction();
}
class StartPlay implements State {
public void doAction() {
System.out.println("start play");
}
}
class StopPlay implements State {
public void doAction() {
System.out.println("stop play");
}
}
class PlayContext implements State {
private State state;
public void setState(State state){
this.state = state;
}
public void doAction() {
this.state.doAction();
}
}
public class StateTest {//тест
public static void main(String[] args) {
PlayContext playContext = new PlayContext();
State startPlay = new StartPlay();
State stopPlay = new StopPlay();
playContext.setState(startPlay);
playContext.doAction();
playContext.setState(stopPlay);
playContext.doAction();
}
}
游客
描述:- 用于简化相关对象分组的操作。
interface Visitor {
void visit(SportCar sportCar);
void visit(Engine engine);
void visit(Whell whell);
}
interface Car {
void accept(Visitor visitor);
}
class Engine implements Car {
public void accept(Visitor visitor) {
visitor.visit(this);
}
}
class Whell implements Car {
public void accept(Visitor visitor) {
visitor.visit(this);
}
}
class SportCar implements Car {
Car[] cars;
public SportCar(){
cars = new Car[]{new Engine(), new Whell()};
}
public void accept(Visitor visitor) {
for (int i = 0; i < cars.length; i++) {
cars[i].accept(visitor);
}
visitor.visit(this);
}
}
class CarVisitor implements Visitor {
public void visit(SportCar computer) {
print("car");
}
public void visit(Engine engine) {
print("engine");
}
public void visit(Whell whell) {
print("whell");
}
private void print(String string) {
System.out.println(string);
}
}
public class VisitorTest {//тест
public static void main(String[] args) {
Car computer = new SportCar();
computer.accept(new CarVisitor());
}
}
口译员
描述:- 允许您为问题域定义简单的语言语法。
interface Expression {
String interpret(Context context);
}
class Context {
public String getLowerCase(String s){
return s.toLowerCase();
}
public String getUpperCase(String s){
return s.toUpperCase();
}
}
class LowerExpression implements Expression {
private String s;
public LoverExpression(String s) {
this.s = s;
}
public String interpret(Context context) {
return context.getLoverCase(s);
}
}
class UpperExpression implements Expression {
private String s;
public UpperExpression(String s) {
this.s = s;
}
public String interpret(Context context) {
return context.getUpperCase(s);
}
}
public class InterpreterTest {//тест
public static void main(String[] args) {
String str = "TesT";
Context context = new Context();
Expression loverExpression = new LoverExpression(str);
str = loverExpression.interpret(context);
System.out.println(str);
Expression upperExpression = new UpperExpression(str);
str = upperExpression.interpret(context);
System.out.println(str);
}
}
迭代器
描述:- 顺序访问集合对象的元素,而不知道其底层表示。
interface Iterator {
boolean hasNext();
Object next();
}
class Numbers {
public int num[] = {1 , 2, 3};
public Iterator getIterator() {
return new NumbersIterator();
}
private class NumbersIterator implements Iterator {
int ind;
public boolean hasNext() {
if(ind < num.length) return true;
return false;
}
public Object next() {
if(this.hasNext()) return num[ind++];
return null;
}
}
}
public class IteratorTest {//тест
public static void main(String[] args) {
Numbers numbers = new Numbers();
Iterator iterator = numbers.getIterator();
while (iterator.hasNext()) {
System.out.println(iterator.next());
}
}
}
纪念品(守护者)
描述:- 允许您保存对象的当前状态;以后可以恢复该状态。不破坏封装。
import java.util.ArrayList;
import java.util.List;
class Memento {
private String name;
private int age;
public Memento(String name, int age){
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
}
class User {
private String name;
private int age;
public User(String name, int age) {
this.name = name;
this.age = age;
System.out.println(String.format("create: name = %s, age = %s", name, age));
}
public Memento save(){
System.out.println(String.format("save: name = %s, age = %s", name, age));
return new Memento(name, age);
}
public void restore(Memento memento){
name = memento.getName();
age = memento.getAge();
System.out.println(String.format("restore: name = %s, age = %s", name, age));
}
}
class SaveUser {
private List<Memento> list = new ArrayList<Memento>();
public void add(Memento memento){
list.
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