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1、第9章 多線程與Applet
//例程9-1：Pi.java
/*演示采用多線程技術計算圓周率*/
public class Pi{
public static void main(String[] args){
PiCaculator pc = new PiCaculator();
Thread t = new Thread(pc);
t.start();
try{
Thread.sleep (10000); //休眠，等待可能出現的異常情況
t.interrupt ();
2、 }catch(InterruptedException e){
e.printStackTrace();
}
}
}
class PiCaculator implements Runnable{
private double latestPiEstimate;
public void run(){
try{
System.out.print ("Math.PI = "+ Math.PI + "\t" );
calPi(0.00001);
3、
System.out.println ("the latest PI = "+this.latestPiEstimate );
}catch(InterruptedException e){
System.out.println("The caculator is Interrupted.");
}
}
/**用于計算圓周率的方法，accuracy為計算精度*/
private void calPi(double accuracy) throws Int
4、erruptedException
{
this.latestPiEstimate =0.0;
long iteration = 0;
int sign = -1;
//按給定精度計算圓周率
while(Math.abs (Math.PI-this.latestPiEstimate)>accuracy){
if(Thread.interrupted ())
throw new InterruptedException();
iteration++;
5、 sign = -sign;
this.latestPiEstimate += (sign*4.0/(2*iteration-1));
}
}
}
//例程9-2：SynDemo.java
/*演示沒有進行線程同步所帶來的問題*/
public class SynDemo{
public static void main(String[] args){
Demostrator shareDemostrator = new Demostrator();
Thread t1 = new Thread(shar
6、eDemostrator,"t1");
Thread t2 = new Thread(shareDemostrator,"t2");
t1.start();
t2.start();
}
}
class Demostrator implements Runnable{
private int shareData = 0;
public void run(){
Thread t = Thread.currentThread ();
for(int i =
7、1; i <= 5; i++){
int copy = shareData;
try{
Thread.sleep ((int)(Math.random ()*1000));
}catch(Exception e){
e.printStackTrace();
}
System.out.println ("Thread "+t.getName ()+": copy="+copy
+"\tshareData=&qu
8、ot;+shareData);
shareData++;
}
}
}
//例程9-3：DeadLockDemo.java
public class DeadLockDemo{
public static void main(String[] args){
DemoObject a = new DemoObject();
DemoObject b = new DemoObject();
a.another = b;
b.another = a;
Thread t1 = new Thread
9、(a,"t1");
Thread t2 = new Thread(b,"t2");
t1.start ();
t2.start ();
}
}
class DemoObject implements Runnable{
public DemoObject another = null;
public void run(){
this.method ();
}
public synchronized void method(){
if(
10、this.another != null){
try{
Thread.sleep (1000);
}catch(Exception e){
e.printStackTrace();
}
another.method ();
//下面的代碼段實際上是執(zhí)行不到的
System.out.println ("If you can see this line,no
deadlock happened");
}
}
}
11、 //例程9-4: ThreeThreadDemo.java
/*ThreeThreadDemo.java*/
public class ThreeThreadDemo{
public static void main(String[] args){
//創(chuàng)建新線程
CustomThread ct1 = new CustomThread(0);
CustomThread ct2 = new CustomThread(1);
//啟動新線程
ct1.start ();
ct2.start ();
//輸出main線程信息
12、 for(int i = 0; i < 5; i++){
System.out.println("main thread: "+i);
}
System.out.println ("main thread has done!");
}
}
class CustomThread extends Thread{
int id;
public CustomThread(int customThreadID){
this.id = customThreadID;
}
//重定義子線程的ru
13、n()方法
public void run(){
//輸出自定義線程的信息
for(int i = 0; i < 5; i++){
System.out.println ("CustomThread #"+ this.id +": "+i);
}
System.out.println ("CustomThread #"+this.id+" has done!");
}
}
//例程9-5：DigitalClock.java
/*采用多線程技術演示一個
14、簡單的數字時鐘*/
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
public class DigitalClock extends JFrame{
public static void main(String[] args) {
JFrame frame = new DigitalClock();
frame.show();
}
public DigitalClock(){
this.setSize(200,150);
15、
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//數字時鐘面板
final ClockPane cp = new ClockPane();
//設置按鈕狀態(tài)并注冊事件監(jiān)聽者
final JButton start = new JButton("start");
final JButton stop = new JButton("stop");
stop.setEnabled(false);
16、start.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
cp.startClock();
start.setEnabled(false);
stop.setEnabled(true);
}
});
stop.addActionListener(new ActionListener(){
pu
17、blic void actionPerformed(ActionEvent e){
cp.stopClock ();
start.setEnabled(true);
stop.setEnabled(false);
}
});
//設置面板布局
JPanel buttomPane = new JPanel();
buttomPane.add(start);
buttomPane.add(stop);
JPan
18、el contentPane = new JPanel();
contentPane.setLayout(new BorderLayout());
contentPane.add(cp,BorderLayout.CENTER);
contentPane.add(buttomPane,BorderLayout.SOUTH);
this.setContentPane(contentPane);
this.setResizable(false);
}
}
//例程9-6：ClockPane.java
/*數字時鐘面
19、板的實現類*/
import javax.swing.JPanel;
import java.util.*;
import java.awt.*;
import java.awt.font.FontRenderContext;
import java.awt.geom.*;
import java.text.*;
public class ClockPane extends JPanel implements Runnable {
//線程是否中止的標志
boolean running = false;
//用于顯示當前時間的字符串
String ti
20、me = "Clock";
Font font = new Font("SanSerif", Font.BOLD, 40);
//啟動報時器
public void startClock() {
this.running = true;
Thread t = new Thread(this);
t.start();
}
//終止報時器
public void stopClock() {
this.running = false;
21、 }
//實現Runnable接口的run（）方法
public void run() {
while (this.running) {
//獲取當前時間并轉換成字符串
this.time = DateFormat.getTimeInstance().format(new Date());
this.repaint();
//讓當前線程休眠1秒鐘
try {
Thread.sleep(1000);
22、
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
//輸出當前時間
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setFont(this.font);
FontRen
23、derContext contex = g2.getFontRenderContext();
Rectangle2D bound = this.font.getStringBounds(this.time, contex);
int strX = (int) ((this.getWidth() - bound.getWidth()) / 2);
int strY = (int) ((this.getHeight() - bound.getHeight()) / 2) + 40;
g2.drawString(this.tim
24、e, strX, strY);
}
}
//例程9-7：IOPipeDemo.java
/*演示采用管道機制的線程間通信*/
import java.io.*;
public class IOPipeDemo{
public static void main(String[] args){
try{
//創(chuàng)建并連接管道
final PipedOutputStream pout = new PipedOutputStream();
final PipedInputStream pin = new Pip
25、edInputStream(pout);
//創(chuàng)建并啟動輸出線程
Thread outputThread = new Thread(new Runnable(){
public void run(){
writeBytes(pout);
}
});
outputThread.start();
//創(chuàng)建并啟動輸入線程
Thread inputThread = new Thread(new Runnable(){
public v
26、oid run(){
readBytes(pin);
}
});
inputThread.start();
}catch(IOException e){
e.printStackTrace();
}
}
//往管道中寫入數據
public static void writeBytes(OutputStream outstream){
try{
DataOutputStream out = new DataOutput
27、Stream(
new BufferedOutputStream(outstream)
);
Thread t = Thread.currentThread ();
for(int i=0; i<10; i++){
System.out.println ("write integer "+i+" to pipe.");
out.writeInt(i);
t.yield ();
}
out.flush(
28、);
out.close();
System.out.println ("Write data to pipe has done");
}catch(IOException e){
e.printStackTrace();
}
}
//從管道中讀取數據
public static void readBytes(InputStream inputstream){
try{
DataInputStream in = new DataInp
29、utStream(
new BufferedInputStream(inputstream)
);
Thread t = Thread.currentThread ();
boolean eof = false;
while(!eof){
try{
int i = in.readInt();
System.out.println("Read integer "+i+" from pipe");
t
30、.yield ();
}catch(EOFException e){
eof = true;
}
}
System.out.println ("Read data from pipe has done");
}catch(IOException e){
e.printStackTrace();
}
}
}
//例程9-8 Hello_World.java
import javax.swing.*;
import java
31、.awt.*;
public class Hello_world extends JApplet{
public void paint(Graphics g){
g.drawString("Hello,world!"，5，10);
}
}
HelloWorld.html 代碼
<HTML>
<HEAD><TITLE>HELLO,WORLD!</TITLE></HEAD>
<BODY>
<APPLET code="Hello_World.class" width=300 height=300></APPLET>
</BODY>
</HTML>
Java程序設計教程 冶金工業(yè)出版社第9章
