常见设计模式代码二

四 代理模式

类图：

代码：

抽象方法：
public abstract class AbstractObject {

public abstract void option();
}

具体实现：
public class RealObject extends AbstractObject {

@Override
public void option() {
System.out.println("real method...");
}
}

代理：
public class ProxyObject extends AbstractObject {

private RealObject realObject=new RealObject();
@Override
public void option() {

System.out.println("执行任务前 检查....");
realObject.option();
}
}

五 观察者模式

观察者模式类图 ：

观察者操作抽象
public interface Observer {

public void update();
}

观察者A B

public class ObserverA implements Observer{
@Override
public void update() {
System.out.println("ObserverA 执行操作");
}
}

public class ObserverB implements Observer {
@Override
public void update() {
System.out.println("ObserverB 执行操作");
}
}

目标操作抽象：
public interface Subject {

public void option();
}

目标更新操作：
public class MySubject implements Subject{
@Override
public void option() {
System.out.println("目标对象执行操作通知观察者.....");
}
}

通知观察者：
public abstract class AbstractSubject implements Subject {

private Vector<Observer> observers = new Vector<Observer>();

public void addObserver(Observer observer) {

observers.add(observer);
}

public void delObserver(Observer observer) {

observers.remove(observer);
}

public void notifyObservers() {

for (Observer observer : observers) {

observer.update();
}
}
}

客户端调用：

AbstractSubject subject = new MySubject();
subject.add(new ObserverA());
subject.add(new ObserverB());
subject.operation();

六 策略模式

策略模式类图

策略模式代码

抽象策略
public interface MemberStrategy {

public double calcPrice(double booksPrice);
}
普通会员：
public class CommonVip implements MemberStrategy{
@Override
public double calcPrice(double booksPrice) {
System.out.println("普通会员....");
return booksPrice*0.9;
}
}
高级会员：
public class AdvancedVip implements MemberStrategy {
@Override
public double calcPrice(double booksPrice) {
System.out.println("高级会员...");
return booksPrice*0.8;
}
}

计算价格类：

public class Price {

private MemberStrategy memberStrategy;

public Price(MemberStrategy memberStrategy) {
this.memberStrategy = memberStrategy;
}

public double quote(double bookPrice) {

return memberStrategy.calcPrice(bookPrice);
}
}