java实现观测者模式

public class Customer extends AbstractCustomer{

private String name;
private Subject subject;
Customer(String name, Subject Subject){
this.name = name;
this.subject = Subject;
}

@Override
public void update() {
System.out.println(subject.getStatus() + name);
}
}public abstract class AbstractCustomer {

public abstract void update();
}
public class Customer extends AbstractCustomer{

private String name;
private Subject subject;
Customer(String name, Subject Subject){
this.name = name;
this.subject = Subject;
}

@Override
public void update() {
System.out.println(subject.getStatus() + name);
}
}public class Subject extends AbstractSubject {
private String status = "closed";

public Subject(String s){
setStatus(s);
}

public String getStatus(){
return status;
}
public void setStatus(String s){
this.status = s;
}

}public class TestObserver {

public static void main(String[] args){
Subject subject = new Subject("tem");

Customer customerA = new Customer("A", subject);
Customer customerB = new Customer("B", subject);
subject.addCustomer(customerA);
subject.addCustomer(customerB);
subject.notifyCustomer();
subject.setStatus("hello");
subject.notifyCustomer();
}
}