java觀察者代碼 java觀察者模式與消息隊(duì)列

java中的觀察者模式，中間的幾行代碼怎么理解呀？？？這種風(fēng)格的代碼很少見呀？？求大神分析下

第一個(gè)

專注于為中小企業(yè)提供成都網(wǎng)站制作、網(wǎng)站建設(shè)服務(wù),電腦端+手機(jī)端+微信端的三站合一,更高效的管理,為中小企業(yè)海南州免費(fèi)做網(wǎng)站提供優(yōu)質(zhì)的服務(wù)。我們立足成都，凝聚了一批互聯(lián)網(wǎng)行業(yè)人才，有力地推動(dòng)了超過千家企業(yè)的穩(wěn)健成長，幫助中小企業(yè)通過網(wǎng)站建設(shè)實(shí)現(xiàn)規(guī)模擴(kuò)充和轉(zhuǎn)變。

public interface RandomNumberListener {//接口

public void numberChanged(double d);

}

第二個(gè)

public class Consol implements RandomNumberListener{

@Override

public void numberChanged(double d) {

System.out.println(d);

}

}

第三個(gè)

public class SwingWindow

extends JFrame

implements RandomNumberListener{//觀察者

private JLabel label = new JLabel();

public SwingWindow(){

this.getContentPane().add( label);

this.setSize(300,200);

this.setVisible(true);

}

@Override

public void numberChanged(double d) {

label.setText(String.valueOf(d));

}

}

第四個(gè)

public class RandomNumber {//業(yè)務(wù)

private double r;

private ListRandomNumberListener listeners = new ArrayListRandomNumberListener();

//添加所有觀察者

public void addRandomNumberListener(RandomNumberListener lis){

listeners.add(lis);

}

public void random(){

r = Math.random();

//數(shù)據(jù)發(fā)生改變，通知所有的觀察者

for (RandomNumberListener lis : listeners) {

lis.numberChanged(r);

}

}

}

第五個(gè)

public class Test {

public static void main(String[] args) throws InterruptedException{

RandomNumber rn = new RandomNumber();

SwingWindow sw = new SwingWindow();

Consol c = new Consol();

rn.addRandomNumberListener(sw);

rn.addRandomNumberListener(c);

while(true){

rn.random();

Thread.sleep(new Random().nextInt(3000)+1000L);

}

}

}

JAVA觀察者模式(observer pattern)

import?java.util.ArrayList;

import?java.util.HashMap;

import?java.util.Random;

import?javax.swing.event.ChangeEvent;

import?javax.swing.event.ChangeListener;

public?class?StockLists?implements?Runnable

{

private?HashMapString,?Stock?????????????????????hmStocks?=?new?HashMapString,?Stock();

private?HashMapString,?ArrayListChangeListener?hmCL?????=?new?HashMapString,?ArrayListChangeListener();

public?StockLists()

{

init(100);

new?Thread(this).start();

}

public?void?run()

{

Random?rand?=?new?Random();

while?(true)

{

try

{

Thread.sleep(100);

Stock?s?=?randStock();

s.price?=?rand.nextFloat();

ArrayListChangeListener?alCL?=?hmCL.get(s.symbol);

if?(alCL?==?null)

{

continue;

}

for?(ChangeListener?cl?:?alCL)

{

cl.stateChanged(new?ChangeEvent(s));

}

}

catch?(InterruptedException?e)

{

e.printStackTrace();

}

}

}

private?Stock?randStock()

{

Random?rand?=?new?Random();

int?idx?=?rand.nextInt(hmStocks.size());

String?sym?=?(String)?hmStocks.keySet().toArray()[idx];

Stock?s?=?hmStocks.get(sym);

return?s;

}

public?boolean?addChangeListener(ChangeListener?cl,?String?sym)

{

ArrayListChangeListener?al?=?hmCL.get(sym);

if?(al?==?null)

{

al?=?new?ArrayListChangeListener();

hmCL.put(sym,?al);

}

return?al.add(cl);

}

private?void?init(int?count)

{

Random?rand?=?new?Random();

for?(int?i?=?0;?i??count;?i++)

{

String?sym?=?randSym(rand);

float?p?=?rand.nextFloat();

Stock?s?=?new?Stock(sym,?p);

hmStocks.put(sym,?s);

}

}

private?String?randSym(Random?rand)

{

char[]?ca?=?new?char[3];

for?(int?i?=?0;?i??ca.length;?i++)

{

ca[i]?=?(char)?('A'?+?rand.nextInt(26));

}

return?new?String(ca);

}

public?static?void?main(String[]?args)

{

StockLists?sl?=?new?StockLists();

sl.addChangeListener(new?Investor("111"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("222"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("333"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("444"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("555"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("666"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("777"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("888"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("999"),?sl.randStock().symbol);

sl.addChangeListener(new?Investor("000"),?sl.randStock().symbol);

}

}

class?Stock

{

public?String?symbol?=?null;

public?float??price??=?0.0f;

public?Stock(String?sym,?float?p)

{

symbol?=?sym;

price?=?p;

}

public?String?toString()

{

return?symbol?+?":"?+?price;

}

}

class?Investor?implements?ChangeListener

{

public?String?name?=?"";

public?Investor(String?name)

{

this.name?=?name;

}

@Override

public?void?stateChanged(ChangeEvent?e)

{

Stock?s?=?(Stock)?e.getSource();

System.out.println("Hello,"?+?name?+?"?:?STOCK?CHANGED:?"?+?s);

}

}

求 JAVA 異步觀察者模式 的源代碼（完整的），不要同步的，好的給加分

package TestObserver;

import java.util.Iterator;

import java.util.Vector;

/**

*

* @author Seastar

*/

interface Observed {

public void addObserver(Observer o);

public void removeObserver(Observer o);

public void update();

}

interface Observer {

public void takeAction();

}

class Invoker {

private Observer o;

Handler handler;

public Invoker(Observer o) {

new Handler();

this.o = o;

}

private class Handler extends Thread {

public Handler() {

handler = this;

}

@Override

public void run() {

o.takeAction();

}

}

public boolean TestSameObserver(Observer o) {

return o == this.o;

}

public void invoke() {

handler.start();

}

}

class ObservedObject implements Observed {

private VectorInvoker observerList = new VectorInvoker();

public void addObserver(Observer o) {

observerList.add(new Invoker(o));

}

public void removeObserver(Observer o) {

IteratorInvoker it = observerList.iterator();

while (it.hasNext()) {

Invoker i = it.next();

if (i.TestSameObserver(o)) {

observerList.remove(i);

break;

}

}

}

public void update() {

for (Invoker i : observerList) {

i.invoke();

}

}

}

class ObserverA implements Observer {

public void takeAction() {

System.out.println("I am Observer A ,state changed ,so i have to do something");

}

}

class ObserverB implements Observer {

public void takeAction() {

System.out.println("I am Observer B ,i was told to do something");

}

}

class ObserverC implements Observer {

public void takeAction() {

System.out.println("I am Observer C ,I just look ,and do nothing");

}

}

public class Main {

/**

* @param args the command line arguments

*/

public static void main(String[] args) {

ObserverA a = new ObserverA();

ObserverB b = new ObserverB();

ObserverC c = new ObserverC();

ObservedObject oo = new ObservedObject();

oo.addObserver(a);

oo.addObserver(b);

oo.addObserver(c);

for (int i = 0; i 5; ++i) {

oo.addObserver(new Observer() {

public void takeAction() {

System.out.println("我是山寨觀察者"+"，誰敢攔我");

}

});

}

//sometime oo changed ,so it calls update and informs all observer

oo.update();

}

}

觀察者模式的精髓在于注冊(cè)一個(gè)觀察者觀測(cè)可能隨時(shí)變化的對(duì)象，對(duì)象變化時(shí)就會(huì)自動(dòng)通知觀察者，

這樣在被觀測(cè)對(duì)象影響范圍廣，可能引起多個(gè)類的行為改變時(shí)很好用，因?yàn)闊o需修改被觀測(cè)對(duì)象的代碼就可以增加被觀測(cè)對(duì)象影響的類，這樣的設(shè)計(jì)模式使得代碼易于管理和維護(hù)，并且減少了出錯(cuò)幾率

至于異步機(jī)制實(shí)際是個(gè)噱頭，可以有觀測(cè)對(duì)象來實(shí)現(xiàn)異步，也可以有觀察者自身實(shí)現(xiàn)，這個(gè)程序?qū)嶋H是觀測(cè)對(duì)象實(shí)現(xiàn)了異步機(jī)制，方法是在觀察者類外包裝了一層invoker類

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