threading-ways.txt

多线程的程序

/* copy from P174~175 on Chinese version of Just Java 2 
irrelevant threading 
to speak out the favorite drink */

public class Drinks{
	public static void main(String[] a){
		Coffee t1 new Coffee(); 
		T1.start(); 
		New Tea().start(); // an anonymous thread
}
}

class Coffee extends Thread{
	public void run(){
		while(true){
			System.out.prinln(“I prefer coffee. ”); 
			yield(); 
		}
	}
}

class Tea extends Thread{
	public void run(){
		while(true){
			System.out.prinln(“I prefer tea. ”); 
			yield(); 
		}
	}
}















/* copy from P176~177 on Chinese version of Just Java 2 
relevant, non-synchronized threading 
to find out a prime */

public class testPrime{
	public static void main(String s[]){
		long possPrime = Long.parseLong(s[0]); 
		int centuries = (int)(possPrime/100)+1; 
		for(int i=0; i<centuries; i++){
			new testRange(i*100, possPrime).start(); 
		}
}
}

class testRange extends Thread{
	static long possPrime; 
	long from, to; 

	testRange(int argFrom, long argpossPrime){
		possPrime = argpossPrime; 
		if(argFrom=0) from=2; 
		else from=argFrom; 
		to = argFrom + 99; 
}
public void run(){
	for(long i=from; i<=to && i<possPrime; i++){
	if(possPrime%i == 0){
	System.out.println(“factor ”+i+“ found by thread “+getName()); 
	break; 
}
yield(); 
}
}
}










/* copy from P180~181 on Chinese version of Just Java 2 
exclusive threading 
to check the air pressure to keep it in range */

public class p{
	static int pressureGauge=0; 
	static final int safetyLimit=20; 
	public static void main(String[] args){
		pressure []p1 = new pressure[10]; 
		for(int i=0; i<10; i++){
			p1[i] = new pressure(); 
			p1[i].start(); 
		}
		try{
			for(int i=0; i<10; i++){
				p1[i].join(); 
} catch(Exception e){}
System.out.print(“gauge reads”+pressureGauge); 
System.out.println(“; safe limit is 20. ”); 
}
}

class pressure extends Thread{
	static synchronized void RaisePressure(){
		if(p.pressureGauge < p.safetyLimit-15){
			try{sleep(100); } catch(Exception e){} // delay
			p.pressureGauge += 15; 
}
else ; // pressure too high
}
public void run(){
	RaisePressure(); 
}
}










/* copy from P187~189 on Chinese version of Just Java 2 
alternate exclusive threading 
to check the air pressure to keep it in range */

public class plum{
	public static void main(String args[]){
		Producer p = new Producer(); 
		Consumer c = new Consumer(p); 
		p.start(); 
		c.start(); 
}
}

class Producer extends Thread{
	private String [] buffer = new String[8]; 
	private int pi = 0; // produce index
	private int gi = 0; // get index

	public void run(){
		for(;;) produce(); 
}
private final long start = System.currentTimeMillis(); 
private final String banana(){
	return “” + (int) (System.currentTimeMillis() - start); 
}
synchronized void produce(){
	while (pi-gi+1 > buffer.length){
		try{wait(); } catch(Exception e){}
} // while there is no room in the buffer
buffer[pi&0x7] = banana(); 
System.out.println(“produced[” +(pi&0x7) +”]” +buffer[pi&0x7]); 
pi++; 
notifyAll(); 
}
synchronized String consume(){
	while (pi==gi){
		try{wait(); } catch(Exception e){}
} // while there is nothing left to take from the buffer
notifyAll(); 
return buffer[ gi+&0x7 ]; 
}
}


class Consumer extends thread{
	Producer whoIamTalkingTo; 
Consumer (Producer who){
	whoIamTalkingTo = who; 
} // Java idiom for a constructor
public void run(){
	java.util.Random r = new java.util.Random(); 
	for(;;){
		String result = whoIamTalkingTo.consume(); 
		System.out.println(“consumed: ” + result); 
		// next line is just to make it run a bit slower
		int randomtime = Math.abs(r.nextint() % 250); 
		try{sleep(randomtime); } catch(Exception e){}
}
}
}