用java写的生产者消费者问题的源代码及解释

/**
* @function 提供了生产者消费者问题的源代码
* @author 郑路路
* @time 2013/3/16
*/

public class ProblemTest {
public static void main(String[] args){
BreadStack bs = new BreadStack();    //得到一个面包框的对象
Producer p = new Producer(bs);       //得到一个生产者对象
Consumer c = new Consumer(bs);       //得到一个消费者对象
//有几个生产者线程就对应几个消费者线程
new Thread(p).start();
new Thread(p).start();
new Thread(c).start();
new Thread(c).start();
}
}
/*
* 定义面包的类，给每个面包一个编号
*/
class Bread{
private int id;
Bread(int id){
this.id = id;
}

public String toString(){
return "bread: " + id;
}
}
/*
* 定义面包框的类
*/
class BreadStack{
private int index = 0;
private Bread[] breads = new Bread[6];

public Bread[] getBreads() {
return breads;
}
public void setBreads(Bread[] breads) {
this.breads = breads;
}
public int getIndex() {
return index;
}
public void setIndex(int index) {
this.index = index;
}
public synchronized void push(Bread b){
while(index == breads.length){
try {
//在等待之前先唤醒在此对象监视器上等待的所有线程
this.notifyAll();
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}

}
breads[index] = b;
index ++;
}
public synchronized Bread pop(){
while(index == 0){
try {
//在等待之前先唤醒在此对象监视器上等待的所有线程
this.notifyAll();
this.wait();
} catch (InterruptedException e) {
e.printStackTrace();
}

}
index --;
return breads[index];
}
}
/*
* 定义生产者的类
*/
class Producer implements Runnable{
private BreadStack bs = null;

Producer(BreadStack bs) {
this.bs = bs;
}
public void run() {
//一个生产者最多只能生产20个馒头
for(int i=0; i<20; i++){
Bread bread = new Bread(i);
bs.push(bread);
System.out.println("生产了" + bread);
//生产一个馒头之后休息1s钟的时间
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
/*
* 定义消费者的类
*/
class Consumer implements Runnable{
private BreadStack bs = null;

Consumer(BreadStack bs) {
this.bs = bs;
}
public void run() {
//一个生产者最多只能消费20个馒头
for(int i=0; i<20; i++){
Bread bread = bs.pop();
System.out.println("消费了" + bread);
//消费一个馒头之后休息1s钟的时间
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}