【Java基础之设计模式】代码库(三)

抽象工厂模式.java

//抽象工厂
public abstract class AbstractFactory {
public abstract Vehicle create();
public abstract Weapon create();
public abstract Food create();
}

//工厂
public class Factory extends AbstractFactory {
@Override
public Vehicle create() {
return new RangeRover();
}

@Override
public Weapon create() {
return new AK47();
}

@Override
public Food create() {
return new Apple();
}
}

//测试
public class Test {
public static void main(String[] args) {
AbstractFactory abf = new Factory();

//产品一
Vehicle v = abf.create();
v.run();

//产品二
Weapon w = abf.create();
w.fire();

//产品三
Food f = abf.create();
f.price();
}
}

单例模式.java

//懒汉式
public class Singleton {
private static Singleton instance = null;

//私有构造函数
private Singleton() {

}

public static synchronized getInstance() {
if (instance == null)
instance = new Singleton();

return instance;
}
}

//饿汉式
public class Singleton {
private static final Singleton instance = new Singleton();

private Singleton() {

}

public static Singleton getInstance() {
return instance;
}
}

工厂方法模式.java

//抽象产品角色
public interface Moveable {
void run();
}

//具体产品角色
public class Plane implements Moveable {
@Override
public void run() {
System.out.println("飞机飞起来了！");
}
}

public class Car implements Moveable {
@Override
public void run() {
System.out.println("汽车开起来了！");
}
}

//抽象工厂
public abstract class Factory {
abstract Moveable create();
}

//工厂
public class PlaneFactory extends Factory {
public Moveable create() {
return new Plane();
}
}

public class CarFactory extends Factory {
public Moveable create() {
return new Car();
}
}

//测试
public class Test {
public static void main(String[] args) {
Factory fac = new CarFactory();
Moveable car = fac.create();
car.run();
}
}

观察者模式.java

//抽象观察者
public interface Watcher {
public void update(String str);
}

//抽象主题角色（被观察者）
public interface Watched {
public void addWatcher(Watcher watcher);

public void removeWatcher(Watcher watcher);

public void notifyWatchers(String str);
}

//观察者
public class ConcreteWatcher implements Watcher {
@Override
public void update(String str) {
System.out.println(str);
}
}

//主题角色
public class ConcreteWatched implements Watched {
private List<Watcher> list = new ArrayList<>();

@Override
public void addWatcher(Watcher watcher) {
list.add(watcher);
}

@Override
public void removeWatcher(Watcher watcher) {
list.remove(watcher);
}

@Override
public void notifyWatchers(String str) {
for (Watcher watcher : list) {
watcher.update(str);
}
}
}

//测试
public class Test {
public static void main(String[] args) {
Watched girl = new ConcreteWatched();

Watcher boy1 = new ConcreteWatcher();
Watcher boy2 = new ConcreteWatcher();
Watched boy3 = new ConcreteWatcher();

//注册
girl.addWatcher(boy1);
girl.addWatcher(boy2);
girl.addWatcher(boy3);

girl.notifyWatchers("我美不美？");
}
}