JAVA-多线程机制中关于生产者消费者模型

关于多线程的问题

1.  关于多线程生产者的职责是什么？

如果共享数据没有被消费，则生产者等消费者消费；生产者被唤醒生产后，要通知消费者

2.  关于多线程消费者的职责是什么？

如果共享数据已没有了，则消费者等待生产者生产，消费者被唤醒消费后，要通知生产者

代码如下：

//PC.java  by kakasi in 20160102

import static common.IO.*;	//println(xxxx)=System.out.println(xxxx)

//sign
enum State{PUTOVER, GETOVER, UNKNOWN};

//shared data
class Data{
private int count = 0;
private boolean isEmpty = true;
private State state = State.UNKNOWN;

public synchronized void get() throws Exception{
//empty, then wait or return directly
if (isEmpty){
//put is over, return directly
if (state == State.PUTOVER){
state = State.GETOVER;
println("put is over");
println("get is over.");
return;
}
//put is not over, then wait
println("consumer wait.");
wait();
}
//not empty
this.count--;	//consume only one every time
if (this.count == 0){
isEmpty = true;
}
println("get() " + 1);	//consumer information
println("after get(), remains " + this.count);
notify();
}

public synchronized void put(int count) throws Exception{
//not empty, then wait
if (!isEmpty){
println("producer wait.");
wait();
}
//empty
this.count = count;
if (this.count > 0){
isEmpty = false;
}
println("after put(), remains " + count);
notify();
}

public void setState(State state){
this.state = state;
}

public State getState(){
return state;
}
}

//producer
class Producer implements Runnable{
private Data data;

public Producer(Data data){
this.data = data;
}

public void run(){
for(int i = 1; i < 5; i++){
try{
data.put(i);
}catch(Exception e){}
}
//state = PUTOVER
this.data.setState(State.PUTOVER);
}
}

//consumer
class Consumer implements Runnable{
private Data data;

public Consumer(Data data){
this.data = data;
}

public void run(){
//loop while state != GETOVER
while(this.data.getState() != State.GETOVER){
try{
data.get();
}catch(Exception e){}
}
}
}

//runner
class Test{
public static void main(String[] args) throws Exception{
Data data = new Data();
new Thread(new Producer(data)).start();
new Thread(new Consumer(data)).start();
}
}

结果如下：



转载请注明出处，谢谢！