观察者模式_简单例子.doc

实验五、观测者模式（4学时）【实验目的】1、了解观测者模式的应用场景、目的和解决问题的方法。2、掌握观测者模式的结构、各角色之间的协作过程和代码实现。3、了解观测者模式的应用。【实验性质】验证性实验【实验内容与步骤】1、 用Java或C#语言实现观测者模式的结构，并用代码说明客户端程序如何应用观测者模式。观察者public interface Observer public void update ();具体观察者public class ConcreteObserver implements Observer private Subject mConcreteSubject;public ConcreteObserver(Subject mConcreteSubject) this.mConcreteSubject = mConcreteSubject ; public void update () System.out.println(得到信息:+mConcreteSubject.getInformation(); 主题public interface Subject public void attach (Observer o);public void detach (Observer o); public String getInformation(); public void notifyObservers (); public String setInformation(String s);具体主题import java.util.ArrayList; public class ConcreteSubject implements Subject public ArrayList mObserver; private String Information=; private Object mState; public ConcreteSubject() mObserver=new ArrayList(); public Object getState () return mState; public void setState (Object val) mState=val; public void attach (Observer o) if(o!=null) mObserver.add(o); public void detach (Observer o) if(mObserver.contains(o) mObserver.remove(o); public String setInformation(String s) Information=s; return s; public String getInformation() return Information; public void notifyObservers () for(int i=0;imObserver.size();i+) Observer o= mObserver.get(i); o.update(); 客户端public class Application public static void main(String args) Subject s=new ConcreteSubject(); Observer o1=new ConcreteObserver(s); Observer o2=new ConcreteObserver(s); s.attach(o2); s.attach(o1); s.setInformation(你好); s.notifyObservers(); 2、请用观测者模式实现一个汽车驾驶室仪表系统，当汽车改变速度、改变方向时实时显示汽车的速度、方向、指示灯等信息。观察者速度表package driver;import java.util.Observable;import java.util.Observer;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class SpeedA implements Observer JTextField text=new JTextField(); Observable o; int speed=0; public SpeedA(Observable o) text.setVisible(true); this.o = o; o.addObserver(this); public JTextField getText() return text; public void update(Observable o, Object arg) if(o instanceof car) car c=new car(); c=(car)o; speed=c.getspeed(); text.setText(+c.getspeed(); 观察者转向灯package driver;import java.util.Observable;import java.util.Observer;import java.util.Observable;import java.util.Observer;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class turnlight implements Observer JTextField text1=new JTextField(); JTextField text2=new JTextField(); Observable o; String s=; public turnlight(Observable o) this.o = o; o.addObserver(this); public JTextField getText1() return text1; public JTextField getText2() return text2; public void update(Observable o, Object arg) if(o instanceof car) car c=new car(); c=(car)o; s=c.getturn(); if(s=左转) text1.setBackground(Color.red); text2.setBackground(Color.BLACK); if(s=右转) text1.setBackground(Color.BLACK); text2.setBackground(Color.red); 观察者方向package driver;import java.util.Observable;import java.util.Observer;import java.util.Observable;import java.util.Observer;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class direction implements Observer JTextField text=new JTextField(); Observable o; String s=; public direction(Observable o) this.o = o; o.addObserver(this); public JTextField getText() return text; public void update(Observable o, Object arg) if(o instanceof car) car c=new car(); c=(car)o; s=c.getdirection(); text.setText(+c.getdirection(); 被观察者carpackage driver;import java.util.Observable;import java.util.Observer;import java.awt.*;import java.awt.event.*;import javax.swing.*;public class car extends Observable implements ActionListener private int speed=30; private String direction=东; private String turn=; JButton jiasu; JButton jiansu; JButton zuozhuan; JButton youzhuan; public car() jiasu=new JButton(加速); jiasu.addActionListener(this); jiansu=new JButton(减速); jiansu.addActionListener(this); zuozhuan=new JButton(左转向); zuozhuan.addActionListener(this); youzhuan=new JButton(右转向); youzhuan.addActionListener(this); public JButton getjiasu() return jiasu; public JButton getjiansu() return jiansu; public JButton getzuozhuanxiang() return zuozhuan; public JButton getyouzhuanxiang() return youzhuan; public int getspeed() return speed; public String getdirection() return direction; public String getturn() return turn; public void change(int speed,String direction,String turn) this.speed=speed; this.direction=direction; this.turn=turn; this.setChanged(); this.notifyObservers(); public void actionPerformed(ActionEvent e) if(e.getSource()=jiasu) int s=speed+10; String d=direction; String t=turn; change(s,d,t); if(e.getSource()=jiansu) int s=0; if(speed=0) s=0; else s=(speed-10); String d=direction; String t=turn; change(s,d,t); if(e.getSource()=zuozhuan) int s=speed; String d=direction; String t=左转; if(direction=东) change(s,北,t); else if(direction=西) change(s,南,t); else if(direction=南) change(s,东,t); else if(direction=北) change(s,西,t); if(e.getSource()=youzhuan) int s=speed; String d=direction; String t=右转; if(direction=东) change(s,南,t); else if(direction=西) change(s,北,t); else if(direction=南) change(s,西,t); else if(direction=北) change(s,东,t);主框架package driver;import java.util.Observable;import java.util.Observer;import java.awt.*;import java.awt.event.*;import javax.swing.*;/* * * author 郑李斌 */public class Main extends JFrame Main() this.setLayout(null); setBounds(20, 20, 500, 300); JLabel su=new JLabel(速度km/h:); su.setBounds(20, 60, 60, 20); add(su); JLabel dir=new JLabel(方向:); dir.setBounds(20, 80, 60, 20); add(dir); car c=new car(); SpeedA s=new SpeedA(c); direction d=new direction(c); turnlight t=new turnlight(c); c.addObserver(t); c.addObserver(d); c.addObserver(s); JButton jiasu=c.getjiasu(); JButton jiansu=c.getjiansu(); JButton zuozhuan=c.getzuozhuanxiang(); JButton youzhuan=c.getyouzhuanxiang(); jiasu.setBounds(20, 20, 60, 40); jiansu.setBounds(90, 20, 60, 40); zuozhuan.setBounds(160, 20, 80, 40); youzhuan.setBounds(250, 20, 80, 40); JTextField zuozhuand=t.getText1(); zuozhuand.setBounds(20, 100, 60, 20); zuozhuand.setEditable(false); JTextField youzhuand=t.getText2(); youzhuand.setBounds(200, 100, 60, 20); youzhuand.setEditable(false); JTextField sudu=s.getText(); sudu.setBounds(80, 60, 60, 20); sudu.setEditable(false); JTextField di=d.getText(); di.setBounds(80, 80, 60, 20); di.setEditable(false); add(jiansu); add(jiasu); add(sudu); add(di); add(zuozhuan); add(youzhuan); add(zuozhuand); add(youzhuand); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); /* * param args the command line arguments */ public static void main(String args) / TODO code application logic here new Main(); 2、 从观测者模式的角度剖析并应用java.awt.image.ImageObserver。import java.awt.*;import java.applet.*;import java.awt.image.*;public class Main extends Applet implements ImageObserverImage img;int step=0;/step 用来表述已被下载的那部分图片的高度int percent=0;/percent 用来表述已下载的图片的高度占图片总高度的百分比public void init()img=getImage(getCodeBase(),2.jpg);public void paint(Graphics g)g.drawImage(img,0,0,this);public boolean imageUpdate(Image img_ob,int flags,int x,int y,int width,int height)if(fl