观察者模式和装饰模式
一.验证观察者模式一，实现求职中心的模拟
1.实验内容和源程序
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| Subject.java
public interface Subject{
public void addObserver(Observer o);
public void deleteObserver(Observer o);
public void notifyObservers();
}
Observer.java
public interface Observer{
public void hearTelephone(String heardMess);
}
SeekJobCenter.java
import java.util.ArrayList;
public class SeekJobCenter implements Subject{
String mess;
boolean changed;
ArrayList<Observer> personList;
SeekJobCenter(){
personList=new ArrayList<Observer>();
mess="";
changed=false;
}
public void addObserver(Observer o){
if(!(personList.contains(o)))
personList.add(o);
}
public void deleteObserver(Observer o){
if(personList.contains(o))
personList.remove(o);
}
public void notifyObservers(){
if(changed){
for(int i=0;i<personList.size();i++){
Observer observer=personList.get(i);
observer.hearTelephone(mess);
}
changed=false;
}
}
public void giveNewMess(String str){
if(str.equals(mess))
changed=false;
else{
mess=str;
changed=true;
}
}
}
UniverStudent.java
import java.io.*;
public class UniverStudent implements Observer{
Subject subject;
File myFile;
UniverStudent(Subject subject,String fileName){
this.subject=subject;
subject.addObserver(this);
myFile=new File(fileName);
}
public void hearTelephone(String heardMess){
try{ RandomAccessFile out=new RandomAccessFile(myFile,"rw");
out.seek(out.length());
byte [] b=heardMess.getBytes();
out.write(b);
System.out.print("我是一个大学生,");
System.out.println("我向文件"+myFile.getName()+"写入如下内容:");
System.out.println(heardMess);
}
catch(IOException exp){
System.out.println(exp.toString());
}
}
}
|
Haigui.java
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| import java.io.*;
import java.util.regex.*;
public class HaiGui implements Observer{
Subject subject;
File myFile;
HaiGui(Subject subject,String fileName){
this.subject=subject;
subject.addObserver(this);
myFile=new File(fileName);
}
public void hearTelephone(String heardMess){
try{ boolean boo=heardMess.contains("java程序员")||heardMess.contains("软件");
if(boo){
RandomAccessFile out=new RandomAccessFile(myFile,"rw");
out.seek(out.length());
byte [] b=heardMess.getBytes();
out.write(b);
System.out.print("我是一个海归,");
System.out.println("我向文件"+myFile.getName()+"写入如下内容:");
System.out.println(heardMess);
}
else{
System.out.println("我是海归,这次的信息中没有我需要的信息");
}
}
catch(IOException exp){
System.out.println(exp.toString());
}
}
}
|
Application.java
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| public class Application{
public static void main(String args[]){
SeekJobCenter center=new SeekJobCenter();
UniverStudent zhangLin=new UniverStudent(center,"A.txt");
HaiGui wangHao=new HaiGui(center,"B.txt");
center.giveNewMess("腾辉公司需要10个java程序员。");
center.notifyObservers();
center.giveNewMess("海景公司需要8个动画设计师。");
center.notifyObservers();
center.giveNewMess("仁海公司需要9个电工。");
center.notifyObservers();
center.giveNewMess("仁海公司需要9个电工。");
center.notifyObservers();
}
}
|
2.实验执行结果
3.本次收获体会
本问题实现观察者接口Observer的类有两个：一个是UniversityStudent的类，另一个是Haigui。UniversityStudent类的调用方法是会见参数引用的字符串保存到一个文件中。
二.验证装饰模式程序二，实现鸟类飞翔的模拟
1.实验内容和源程序
Bird.java
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| public abstract class Bird{
public abstract int fly();
}
|
Sparrow.java
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| public class Sparrow extends Bird{
public final int DISTANCE=100;
public int fly(){
return DISTANCE;
}
}
|
Decorator.java
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| public abstract class Decorator extends Bird{
protected Bird bird;
public Decorator(){
}
public Decorator(Bird bird){
this.bird=bird;
}
}
|
SparrowDecorator.java
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| public abstract class Decorator extends Bird{
protected Bird bird;
public Decorator(){
}
public Decorator(Bird bird){
this.bird=bird;
}
}
|
Application.java
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| public class Application{
public void needBird(Bird bird){
int flyDistance=bird.fly();
System.out.println("这只鸟能飞行"+flyDistance+"米");
}
public static void main(String args[]){
Application client=new Application();
Sparrow sparrow=new Sparrow();
SparrowDecorator sparrowDecorator1=
new SparrowDecorator(sparrow);
SparrowDecorator sparrowDecorator2=
new SparrowDecorator(sparrowDecorator1);
client.needBird(sparrowDecorator1);
client.needBird(sparrowDecorator2);
}
}
|
2.实验执行结果
3.本次收获体会
装饰模式中非常重要的一点就是“具体组件”和“装饰”都是“抽象组件”的子类。用户如果需要电泳“被装饰者”源氏的方法就让“抽象组件”声明的对象存放装饰者的作用。
三.设计使用多个装饰者的鸟类飞翔程序
1.实验内容和源程序
Bird.java
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| public abstract class Bird{
public abstract int fly();
}``
|
Sparrow.java
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| public class Sparrow extends Bird{
public final int DISTANCE=60;
public int fly(){
return DISTANCE;
}
}
|
Decorator.java
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| public abstract class Decorator extends Bird{
protected Bird bird;
public Decorator(){
}
public Decorator(Bird bird){
this.bird=bird;
}
}
|
SparrowDecorator.java
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| public class SparrowDecorator extends Decorator{
public final int DISTANCE=40;
SparrowDecorator(Bird bird){
super(bird);
}
public int fly(){
int distance=0;
distance=bird.fly()+eleFly();
return distance;
}
private int eleFly(){
return DISTANCE;
}
}
|
SparrowDecoratorTwo.java
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| public class SparrowDecoratorTwo extends Decorator{
public final int DISTANCE=20;
SparrowDecoratorTwo(Bird bird){
super(bird);
}
public int fly(){
int distance=0;
distance=bird.fly()+eleFly();
return distance;
}
public int eleFly(){
return DISTANCE;
}
}
|
Application.java
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| public class Application{
public void needBird(Bird bird){
int flyDistance=bird.fly();
System.out.println("这只鸟能飞行"+flyDistance+"米");
}
public static void main(String args[]){
Application client=new Application();
Bird bird1=new SparrowDecoratorTwo(new Sparrow());
Bird bird2=new SparrowDecorator(bird1);
Bird bird3=new SparrowDecorator(bird2);
Bird bird4=new SparrowDecoratorTwo(bird3);
client.needBird(bird1);
client.needBird(bird2);
client.needBird(bird3);
client.needBird(bird4);
}
}
|
2.实验执行结果
3.本次收获体会
由于装饰是抽象组件的一个子类，因此“装饰者”本身也可以作为一个“被装饰者”，这意味着可以使用多个具体装饰类来装饰具体组件的实例。
本文使用 CC BY-NC-SA 3.0 中国大陆 协议许可
具体请参见 知识共享协议
本文链接：https://zyhang8.github.io/2019/11/07/design-exp2/
