用 wait-notify 寫一段程式碼來解決生產者-消費者問題?
阿新 • • 發佈:2019-02-17
一、生產者程式碼:
package com.edu.chapter03.test; import java.util.Vector; import java.util.logging.Level; import java.util.logging.Logger; public class Producer implements Runnable { private final Vector sharedQueue; private final int SIZE; public Producer(Vector sharedQueue, int size) { this.sharedQueue = sharedQueue; this.SIZE = size; } @Override public void run() { // TODO Auto-generated method stub for (int i = 0; i < 7; i++) { System.out.println("Produced:" + i); try { produce(i); } catch (InterruptedException ex) { Logger.getLogger(Producer.class.getName()).log(Level.SEVERE, null, ex); } } } private void produce(int i) throws InterruptedException { //wait if queue is full while (sharedQueue.size() == SIZE) { synchronized (sharedQueue) { System.out.println("Queue is full " + Thread.currentThread().getName() + " is waiting , size: " + sharedQueue.size()); sharedQueue.wait(); } } //producing element and notify consumers synchronized (sharedQueue) { sharedQueue.add(i); sharedQueue.notifyAll(); } } }
二、消費者程式碼:
package com.edu.chapter03.test; import java.util.Vector; import java.util.logging.Level; import java.util.logging.Logger; public class Consumer implements Runnable { private final Vector sharedQueue; private final int SIZE; public Consumer(Vector sharedQueue, int size) { this.sharedQueue = sharedQueue; this.SIZE = size; } @Override public void run() { // TODO Auto-generated method stub while (true) { try { System.out.println("Consumer: " + consume()); Thread.sleep(50); } catch (InterruptedException ex) { Logger.getLogger(Consumer.class.getName()).log(Level.SEVERE, null, ex); } } } private int consume() throws InterruptedException { //wait if queue is empty while (sharedQueue.isEmpty()) { synchronized (sharedQueue) { System.out.println("Queue is empty " + Thread.currentThread().getName() + " is waiting , size: " + sharedQueue.size()); sharedQueue.wait(); } } //otherwise consume element and notify waiting producer synchronized (sharedQueue) { sharedQueue.notifyAll(); return (Integer) sharedQueue.remove(0); } } }
三、測試函式:
package com.edu.chapter03.test; import java.util.Vector; public class ProducerConsumerSolution { public static void main(String[] args) { Vector sharedQueue = new Vector(); int size = 4; Thread prodThread = new Thread(new Producer(sharedQueue, size), "Producer"); Thread consThread = new Thread(new Consumer(sharedQueue, size), "Consumer"); prodThread.start(); consThread.start(); } }