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import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
class Toast {
/**
* 吐司的状态：
* DRY: 烘干的
* BUTTERED: 涂了黄油的
* JAMMED: 涂了果酱的
* <p>吐司的状态只能由DRY->BUTTERED->JAMMED转变
*/
public enum Status {DRY, BUTTERED, JAMMED}
private Status status = Status.DRY;//默认状态为DRY
private final int id;
public Toast(int id) { this.id = id;}
public void butter() {status = Status.BUTTERED;}
public void jam() {status = Status.JAMMED;}
public Status getStatus() {return status;}
public int getId() {return id;}
public String toString() {
return "Toast id: " + id + ", status: " + status;
}
}
@SuppressWarnings("serial")
class ToastQueue extends LinkedBlockingQueue<Toast> {}
/**
* 生产吐司的任务。
*/
class Toaster implements Runnable {
private ToastQueue toastQueue;
private int count = 0;
private Random random = new Random(47);
public Toaster(ToastQueue queue) {
this.toastQueue = queue;
}
@Override
public void run() {
try {
while(!Thread.interrupted()) {
TimeUnit.MILLISECONDS.sleep(300 + random.nextInt(500));
//生产一片吐司，这些吐司是有序的
Toast toast = new Toast(count++);
System.out.println(toast);
//放到toastQueue中
toastQueue.put(toast);
}
} catch (InterruptedException e) {
System.out.println("Toaster interrupted.");
}
System.out.println("Toaster off.");
}
}
/**
* 涂黄油的任务。
*/
class Butterer implements Runnable {
private ToastQueue dryQueue;
private ToastQueue butteredQueue;
public Butterer(ToastQueue dryQueue, ToastQueue butteredQueue) {
this.dryQueue = dryQueue;
this.butteredQueue = butteredQueue;
}
@Override
public void run() {
try {
while(!Thread.interrupted()) {
//在取得下一个吐司之前会一直阻塞
Toast toast = dryQueue.take();
toast.butter();
System.out.println(toast);
butteredQueue.put(toast);
}
} catch (InterruptedException e) {
System.out.println("Butterer interrupted.");
}
System.out.println("Butterer off.");
}
}
/**
* 涂果酱的任务。
*/
class Jammer implements Runnable {
private ToastQueue butteredQueue;
private ToastQueue finishedQueue;
public Jammer(ToastQueue butteredQueue, ToastQueue finishedQueue) {
this.finishedQueue = finishedQueue;
this.butteredQueue = butteredQueue;
}
@Override
public void run() {
try {
while(!Thread.interrupted()) {
//在取得下一个吐司之前会一直阻塞
Toast toast = butteredQueue.take();
toast.jam();
System.out.println(toast);
finishedQueue.put(toast);
}
} catch (InterruptedException e) {
System.out.println("Jammer interrupted.");
}
System.out.println("Jammer off.");
}
}
/**
* 吃吐司的人，消费者。
*/
class Eater implements Runnable {
private ToastQueue finishedQueue;
private int count = 0;
public Eater (ToastQueue finishedQueue) {
this.finishedQueue = finishedQueue;
}
@Override
public void run() {
try {
while(!Thread.interrupted()) {
//在取得下一个吐司之前会一直阻塞
Toast toast = finishedQueue.take();
//验证取得的吐司是有序的，而且状态是JAMMED的
if (toast.getId() != count++ ||
toast.getStatus() != Toast.Status.JAMMED) {
System.out.println("Error -> " + toast);
System.exit(-1);
} else {
//吃掉吐司
System.out.println(toast + "->Eaten");
}
}
} catch (InterruptedException e) {
System.out.println("Eater interrupted.");
}
System.out.println("Eater off.");
}
}
public class ToastOMatic {
public static void main(String[] args) throws Exception {
ToastQueue dryQueue = new ToastQueue();
ToastQueue butteredQueue = new ToastQueue();
ToastQueue finishedQueue = new ToastQueue();
ExecutorService exec = Executors.newCachedThreadPool();
exec.execute(new Toaster(dryQueue));
exec.execute(new Butterer(dryQueue, butteredQueue));
exec.execute(new Jammer(butteredQueue, finishedQueue));
exec.execute(new Eater(finishedQueue));
TimeUnit.SECONDS.sleep(5);
exec.shutdownNow();
}
}
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