JAVA基础11--行为型模式(观察者模式2,备忘录模式)

案例　观察者模式１

public class Subject {
protected List<Observer> list = new ArrayList<Observer>();
public void registerObserver(Observer obs){
list.add(obs);
}
public void removeObserver(Observer obs){
list.add(obs);
}
//通知所有的观察者更新状态
public void notifyAllObservers(){
for (Observer obs : list) {
obs.update(this);
}
}

}
public class ConcreteSubject extends Subject {

private int state;

public int getState() {
return state;
}

public void setState(int state) {
this.state = state;
//主题对象(目标对象)值发生了变化，请通知所有的观察者
this.notifyAllObservers();
}
}

public interface Observer {
void  update(Subject subject);
}
public class ObserverA implements Observer {

private int myState;   //myState需要跟目标对象的state值保持一致！
@Override
public void update(Subject subject) {
myState = ((ConcreteSubject)subject).getState();
}
public int getMyState() {
return myState;
}
public void setMyState(int myState) {
this.myState = myState;
}
}
public class Client {
public static void main(String[] args) {
//目标对象
ConcreteSubject subject = new ConcreteSubject();
//创建多个观察者
ObserverA  obs1 = new ObserverA();
ObserverA  obs2 = new ObserverA();
ObserverA  obs3 = new ObserverA();
//将这三个观察者添加到subject对象的观察者队伍中
subject.registerObserver(obs1);
subject.registerObserver(obs2);
subject.registerObserver(obs3);
//改变subject的状态
subject.setState(3000);
System.out.println("########################");
//我们看看，观察者的状态是不是也发生了变化
System.out.println(obs1.getMyState());
System.out.println(obs2.getMyState());
System.out.println(obs3.getMyState());
//改变subject的状态
subject.setState(30);
System.out.println("########################");
//我们看看，观察者的状态是不是也发生了变化
System.out.println(obs1.getMyState());
System.out.println(obs2.getMyState());
System.out.println(obs3.getMyState());
}
}

案例　观察者模式２

public class ObserverA implements Observer {
private int myState;
@Override
public void update(Observable o, Object arg) {
myState = ((ConcreteSubject)o).getState();
}
public int getMyState() {
return myState;
}
public void setMyState(int myState) {
this.myState = myState;
}
}
public class ConcreteSubject extends Observable {

private int state;
public void set(int s){
state = s;  //目标对象的状态发生了改变

setChanged();  //表示目标对象已经做了更改
notifyObservers(state);  //通知所有的观察者

}
public int getState() {
return state;
}
public void setState(int state) {
this.state = state;
}
}
public class Client {
public static void main(String[] args) {
//创建目标对象Obserable
ConcreteSubject subject = new ConcreteSubject();
//创建观察者
ObserverA obs1 = new ObserverA();
ObserverA obs2 = new ObserverA();
ObserverA obs3 = new ObserverA();

//将上面三个观察者对象添加到目标对象subject的观察者容器中
subject.addObserver(obs1);
subject.addObserver(obs2);
subject.addObserver(obs3);

//改变subject对象的状态
subject.set(3000);
System.out.println("===============状态修改了！");
//观察者的状态发生了变化
System.out.println(obs1.getMyState());
System.out.println(obs2.getMyState());
System.out.println(obs3.getMyState());

subject.set(600);
System.out.println("===============状态修改了！");
//观察者的状态发生了变化
System.out.println(obs1.getMyState());
System.out.println(obs2.getMyState());
System.out.println(obs3.getMyState());

}
}

案例　备忘录模式

public class EmpMemento {
private String ename;
private int age;
private double salary;
public EmpMemento(Emp e) {
this.ename = e.getEname();
this.age = e.getAge();
this.salary = e.getSalary();
}
public String getEname() {
return ename;
}
public void setEname(String ename) {
this.ename = ename;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
}
public class Emp {
private String ename;
private int age;
private double salary;
//进行备忘操作，并返回备忘录对象
public EmpMemento  memento(){
return new EmpMemento(this);
}
//进行数据恢复，恢复成制定备忘录对象的值
public void recovery(EmpMemento mmt){
this.ename = mmt.getEname();
this.age = mmt.getAge();
this.salary = mmt.getSalary();
}
public Emp(String ename, int age, double salary) {
super();
this.ename = ename;
this.age = age;
this.salary = salary;
}
public String getEname() {
return ename;
}
public void setEname(String ename) {
this.ename = ename;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public double getSalary() {
return salary;
}
public void setSalary(double salary) {
this.salary = salary;
}
}
public class CareTaker {
private EmpMemento memento;
//	private List<EmpMemento> list = new ArrayList<EmpMemento>();
public EmpMemento getMemento() {
return memento;
}
public void setMemento(EmpMemento memento) {
this.memento = memento;
}
}

public class Client {
public static void main(String[] args) {
CareTaker taker = new CareTaker();
Emp emp = new Emp("高淇", 18, 900);
System.out.println("第一次打印对象："+emp.getEname()+"---"+emp.getAge()+"---"+emp.getSalary());
taker.setMemento(emp.memento());   //备忘一次
emp.setAge(38);
emp.setEname("搞起");
emp.setSalary(9000);
System.out.println("第二次打印对象："+emp.getEname()+"---"+emp.getAge()+"---"+emp.getSalary());
emp.recovery(taker.getMemento()); //恢复到备忘录对象保存的状态
System.out.println("第三次打印对象："+emp.getEname()+"---"+emp.getAge()+"---"+emp.getSalary());
}
}