1: package fpatterns.Observer_Pattern;
2:
3: public interface Subject {//主題
4: public void registerObserver(Observer ob);// 註冊觀察者
5:
6: public void removeObserver(Observer ob);// 移除觀察者
7:
8: public void notifyObservers();// 通知所有觀察者資料變動
9: }
1: package fpatterns.Observer_Pattern;
2:
3: import java.util.ArrayList;
4:
5: interface Observer {// 觀察者
6: public void updateNum(ArrayList<Integer> al);// 所有觀察者更新資料
7: }
1: package fpatterns.Observer_Pattern;
2:
3: import java.util.ArrayList;
4: import java.util.Random;
5:
6: public class LottoSystem implements Subject, Runnable {// Runnable只用於方便開獎,沒有其他用途
7:
8: ArrayList<Observer> obsal;// 存放所有觀察者
9: ArrayList<Integer> numberal;// 存放樂透數字
10:
11: public LottoSystem() {
12:
13: obsal = new ArrayList<Observer>();
14: numberal = new ArrayList<Integer>();
15: for (int i = 0; i < 6; i++) {// 初始 6 個號碼為 0
16: numberal.add(0);
17: }
18: }
19:
20: public void registerObserver(Observer ob) {
21: obsal.add(ob);
22: }
23:
24: public void removeObserver(Observer ob) {
25: int i = obsal.indexOf(ob);
26: if (i >= 0) {
27: obsal.remove(i);
28: }
29: }
30:
31: // 主題更新資料之後,必須呼叫此方法以通知所有觀察者
32: public void notifyObservers() {
33:
34: for (int i = 0; i < obsal.size(); i++) {
35: Observer ob = (Observer) obsal.get(i);
36: ob.updateNum(numberal);
37: }
38:
39: }
40:
41: public void lottery() {
42: Random r = new Random();
43: for (int i = 0; i < numberal.size(); i++) {
44:
45: int tempnum = r.nextInt(48);
46:
47: for (int j = 0; j < numberal.size(); j++) {
48: if (tempnum == numberal.get(j) && i != j) {
49: tempnum = r.nextInt(48);
50: j = 0;
51: i = 0;
52: }
53: }
54:
55: numberal.set(i, tempnum);
56: }
57:
58: notifyObservers();
59: }
60:
61: // 模擬開獎
62: public void run() {
63: while (true) {
64:
65: lottery();
66:
67: try {
68: Thread.currentThread().sleep(1500);
69: } catch (InterruptedException e) {
70: // TODO Auto-generated catch block
71: e.printStackTrace();
72: }
73: }
74: }
75:
76: }
1: package fpatterns.Observer_Pattern;
2:
3: import java.util.ArrayList;
4:
5: public class ShowLottoNum implements Observer {
6:
7: String name;
8:
9: ArrayList<Integer> numlist;// 存放樂透數字
10:
11: Subject s;// 主題,用來註冊該觀察者
12:
13: // 當觀察者建構自己必須傳入已存在的主題物件以註冊自己本身
14: public ShowLottoNum(Subject s, String name) {
15: this.s = s;
16: s.registerObserver(this);
17: this.name = name;
18: }
19:
20: @Override
21: public void updateNum(ArrayList<Integer> al) {
22: // TODO Auto-generated method stub
23: numlist = al;
24: showNum();
25: }
26:
27: public void showNum() {
28: System.out.print(name + " get number :");
29: for (int i = 0; i < numlist.size(); i++) {
30: System.out.print(numlist.get(i) + ",");
31: }
32: System.out.println();
33: }
34:
35: }
1: package fpatterns.Observer_Pattern;
2:
3: import java.util.ArrayList;
4: import java.util.List;
5:
6: public class Simulator {
7:
8: public static void main(String[] args) {
9:
10: LottoSystem ls = new LottoSystem();// 主題
11:
12: ShowLottoNum sln = new ShowLottoNum(ls, "John");// 觀察者1(若需要更多觀察者,只要照著
13: // ShowLottoNum 建構即可 )
14: ShowLottoNum sln2 = new ShowLottoNum(ls, "Peter");// 觀察者2
15: ShowLottoNum sln3 = new ShowLottoNum(ls, "Little flower");// 觀察3
16:
17: // 開始開獎
18: new Thread(ls).start();
19: }
20:
21: }
標籤： 設計模式