示例示例Java有23种设计模式,它们分别是:工厂模式(Factory Pattern)
Java有23种设计模式,它们分别是:
1. 工厂模式(Factory Pattern)
public class ShapeFactory {
//使用 getShape 方法获取形状类型的对象
public Shape getShape(String shapeType){
if(shapeType == null){
return null;
}
if(shapeType.equalsIgnoreCase("CIRCLE")){
return new Circle();
} else if(shapeType.equalsIgnoreCase("RECTANGLE")){
return new Rectangle();
} else if(shapeType.equalsIgnoreCase("SQUARE")){
return new Square();
}
return null;
}
}
2. 抽象工厂模式(Abstract Factory Pattern)
public abstract class AbstractFactory {
abstract Color getColor(String color);
abstract Shape getShape(String shape) ;
}
public class ShapeFactory extends AbstractFactory {
@Override
public Shape getShape(String shapeType){
if(shapeType == null){
return null;
}
if(shapeType.equalsIgnoreCase("CIRCLE")){
return new Circle();
} else if(shapeType.equalsIgnoreCase("RECTANGLE")){
return new Rectangle();
} else if(shapeType.equalsIgnoreCase("SQUARE")){
return new Square();
}
return null;
}
@Override
Color getColor(String color) {
return null;
}
}
3. 单例模式(Singleton Pattern)
public class Singleton {
private static Singleton instance;
private Singleton(){}
public static Singleton getInstance(){
if(instance == null){
instance = new Singleton();
}
return instance;
}
}
4. 命令模式(Command Pattern)
public intece Order {
void execute();
}
public class BuyStock implements Order {
private Stock abcStock;
public BuyStock(Stock abcStock){
this.abcStock = abcStock;
}
public void execute() {
abcStock.buy();
}
}
5. 观察者模式(Observer Pattern)
public intece Subject {
public void registerObserver(Observer o);
public void removeObserver(Observer o);
public void notifyObservers();
}
public class WeatherData implements Subject {
private ArrayList observers;
private float temperature;
private float humidity;
private float pressure;
public WeatherData(){
observers = new ArrayList();
}
public void registerObserver(Observer o) {
observers.add(o);
}
public void removeObserver(Observer o) {
int i = observers.indexOf(o);
if (i >= 0) {
observers.remove(i);
}
}
public void notifyObservers() {
for (int i = 0; i < observers.size(); i++) {
Observer observer = (Observer)observers.get(i);
observer.update(temperature, humidity, pressure);
}
}
public void measurementsChanged() {
notifyObservers();
}
public void setMeasurements(float temperature, float humidity, float pressure) {
this.temperature = temperature;
this.humidity = humidity;
this.pressure = pressure;
measurementsChanged();
}
}
6. 策略模式(Strategy Pattern)
public intece Strategy {
public int doOperation(int num1, int num2);
}
public class Operation
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