观察者模式代码实现
- 选择合适的设计模式设计以下场景：
猫（Cat）大叫一声，老鼠（Mouse）开始逃跑，主人（Master）被惊醒。
要求：1. 要有联动性，老鼠和主人的行为是被动的；2. 考虑可扩展性，猫的叫声可能引起其他联动效应；3. 给出模式名称及定义，并结合场景绘制结构图。
观察者模式
- 类图：
- 在某多人联机对战游戏中，多个玩家可以加入同一战队组成联盟，当战队中的某一成员受到敌人攻击时将给所有其他盟友发送通知，盟友收到通知后将做出响应。现使用观察者模式设计并实现该过程，以实现战队成员之间的联动。**
- 类图：
- 源代码：
- AllyControlCenter
package com.fish.pattern.observer;
import java.util.ArrayList;
public abstract class AllyControlCenter {
protected String allyName; //战队名
protected ArrayList<Observer> players = new ArrayList<>();
public String getAllyName() {
return allyName;
}
public void setAllyName(String allyName) {
this.allyName = allyName;
}
public void join(Observer obs){
players.add(obs); //加入战队
System.out.println(obs.getName()+"加入"+this.allyName+"战队");
}
public void quit(Observer obs){
players.remove(obs); //推出战队
System.out.println(obs.getName()+"退出"+this.allyName+"战队");
}
public abstract void notifyObserve(String name);
}
- ConcreteAllyControlCenter
package com.fish.pattern.observer;
public class ConcreteAllyControlCenter extends AllyControlCenter {
public ConcreteAllyControlCenter(String allyName) {
this.allyName = allyName;
System.out.println(this.allyName+"战队组建成功！");
}
@Override
public void notifyObserve(String name) {
System.out.println(this.allyName+ "战队紧急通知，盟友"+name+"遭受攻击。。。");
for (Observer obs : players) {
if(!obs.getName().equalsIgnoreCase(name)){
obs.help();
}
}
}
}
- Observer
package com.fish.pattern.observer;
public interface Observer {
String getName();
void setName(String name);
void help();
void beAttacked(AllyControlCenter acc);
}
- Player
package com.fish.pattern.observer;
public class Player implements Observer{
private String name;
@Override
public String getName() {
return this.name=name;
}
@Override
public void setName(String name) {
this.name = name;
}
@Override
public void help() {
System.out.println("坚持住，"+this.name+"来救你！");
}
@Override
public void beAttacked(AllyControlCenter acc) {
System.out.println(this.name+" 被攻击！");
acc.notifyObserve(this.name);
}
}
- Client
package com.fish.pattern.observer;
public class Client {
public static void main(String[] args) {
AllyControlCenter acc;
acc = new ConcreteAllyControlCenter("MyTeam");
Observer player1,player2,player3,player4;
player1 = new Player();
player1.setName("张三");
acc.join(player1);
player2 = new Player();
player2.setName("李四");
acc.join(player2);
player3 = new Player();
player3.setName("王五");
acc.join(player3);
player4 = new Player();
player4.setName("fish");
acc.join(player2);
acc.quit(player4);
player4.beAttacked(acc);
}
}
- 运行结果：
状态模式代码实现
- 用“状态模式”设计一个学生成绩的状态转换程序。本实例包含了“不及格”、“中等”和“优秀”3种状态，当学生的分数小于60分时为“不及格”状态，当分数大于等于60分且小于90分时为“中等”状态，当分数大于等于90分时为“优秀”状态。
- 类图：
- 源代码：
- AbstractState
package com.fish.pattern.state;
public abstract class AbstractState {
protected ScoreContext hj; //环境
protected String stateName; //状态名
protected int score; //分数
public abstract void checkState(); //检查当前状态
public void addScore(int x){
score+=x;
System.out.print("加上："+x+"分，当前分数："+score+"分");
checkState();
System.out.println(",当前状态为："+hj.getState().stateName);
}
}
- HighState
package com.fish.pattern.state;
public class HighState extends AbstractState{
public HighState(AbstractState state){
hj=state.hj;
stateName="优秀";
score=state.score;
}
@Override
public void checkState() {
if (score < 60) {
hj.setState(new LowState(this));
} else if (score >= 60) {
hj.setState(new MiddleState(this));
}
}
}
- LowState
package com.fish.pattern.state;
public class LowState extends AbstractState{
//初始化
public LowState(ScoreContext h) {
hj = h;
stateName = "不及格";
score = 0;
}
public LowState(AbstractState state) {
hj = state.hj;
stateName = "不及格";
score = state.score;
}
@Override
public void checkState() {
if(score>=90){
hj.setState(new HighState(this));
}else if(score>=60){
hj.setState(new MiddleState(this));
}
}
}
- MiddleState
package com.fish.pattern.state;
public class MiddleState extends AbstractState{
public MiddleState(AbstractState state){
hj=state.hj;
stateName="中等";
score=state.score;
}
@Override
public void checkState(){
if(score<60){
hj.setState(new LowState(this));
}else if(score>=90){
hj.setState(new HighState(this));
}
}
}
- ScoreContext
package com.fish.pattern.state;
public class ScoreContext {
private AbstractState state;
public ScoreContext() {
state = new LowState(this);
}
public AbstractState getState() {
return state;
}
public void setState(AbstractState state) {
this.state = state;
}
public void add(int score){
this.state.addScore(score);
}
}
- Client
package com.fish.pattern.state;
public class Client {
public static void main(String[] args) {
ScoreContext account=new ScoreContext();
System.out.println("学生成绩状态测试，初始分值为0：");
account.add(100);
account.add(-40);
account.add(-10);
account.add(50);
account.add(-25);
}
}
- 运行结果：
