最近有網友面試中遇到了,生產者 消費者問題。我在這裏整理一下,分享出來。對於多線程程序來說,不管任何編程語言,生產者和消費者模型都是最經典的。
實際上,準確說應該是“生產者-消費者-倉儲”模型,離開了倉儲,生產者消費者模型就顯得沒有說服力了。
對於此模型,應該明確一下幾點:
- 生產者僅僅在倉儲未滿時候生產,倉滿則停止生產。
- 消費者僅僅在倉儲有產品時候才能消費,倉空則等待。
- 當消費者發現倉儲沒產品可消費時候會通知生產者生產。
- 生產者在生產出可消費產品時候,應該通知等待的消費者去消費。
以下爲全部代碼
package com.xttblog.thread;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
/**
* java多線程模擬生產者消費者問題
* 業餘草 :www.xttblog.com
* ProducerConsumer是主類,Producer生產者,Consumer消費者,Product產品,Storage倉庫
*/
public class ProducerConsumer {
public static void main(String[] args) {
ProducerConsumer pc = new ProducerConsumer();
Storage s = pc.new Storage();
ExecutorService service = Executors.newCachedThreadPool();
Producer p = pc.new Producer("張三", s);
Producer p2 = pc.new Producer("李四", s);
Consumer c = pc.new Consumer("王五", s);
Consumer c2 = pc.new Consumer("老劉", s);
Consumer c3 = pc.new Consumer("老林", s);
service.submit(p);
//service.submit(p2);
service.submit(c);
service.submit(c2);
service.submit(c3);
}
/**
* 消費者
*/
class Consumer implements Runnable {
private String name;
private Storage s = null;
public Consumer(String name, Storage s) {
this.name = name;
this.s = s;
}
public void run() {
try {
while (true) {
System.out.println(name + "準備消費產品.");
Product product = s.pop();
System.out.println(name + "已消費(" + product.toString() + ").");
System.out.println("===============");
Thread.sleep(500);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
/**
* 生產者
*/
class Producer implements Runnable {
private String name;
private Storage s = null;
public Producer(String name, Storage s) {
this.name = name;
this.s = s;
}
public void run() {
try {
while (true) {
Product product = new Product((int) (Math.random() * 10000)); // 產生0~9999隨機整數
System.out.println(name + "準備生產(" + product.toString() + ").");
s.push(product);
System.out.println(name + "已生產(" + product.toString() + ").");
System.out.println("===============");
Thread.sleep(500);
}
} catch (InterruptedException e1) {
e1.printStackTrace();
}
}
}
/**
* 倉庫,用來存放產品
*/
public class Storage {
BlockingQueue<Product> queues = new LinkedBlockingQueue<Product>(10);
public void push(Product p) throws InterruptedException {
queues.put(p);
}
public Product pop() throws InterruptedException {
return queues.take();
}
}
public class Product {
private int id;
public Product(int id) {
this.id = id;
}
public String toString() {
return "產品:" + this.id;
}
}
}
以下爲運行結果張三準備生產(產品:3359).
張三已生產(產品:3359).
===============
老劉準備消費產品.
王五已消費(產品:3359).
===============
王五準備消費產品.
張三準備生產(產品:1863).
張三已生產(產品:1863).
===============
老林已消費(產品:1863).
===============
老林準備消費產品.
張三準備生產(產品:5424).
張三已生產(產品:5424).
老劉已消費(產品:5424).
===============
以上內容均轉載自:http://www.xttblog.com/?p=893