Producer-Consumer 生产者，消费者

这个模式跟Guarded模式有点类似，不过需要一个控制台限制请求方和处理方的频度和数量。

public class ProducerConsumerTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Table table = new Table(3);
        
        new MakerThread("MakerThread1", table , 1000).start();
        new MakerThread("MakerThread2", table , 1000).start();
        new MakerThread("MakerThread3", table , 1000).start();
        
        new TakerThread("TakerThread1", table , 1000).start();
        new TakerThread("TakerThread2", table , 1000).start();
        new TakerThread("TakerThread3", table , 1000).start();
    }
}

class MakerThread extends Thread{
    private final Random random;
    private final Table table;
    private static int id=0;
    
    public MakerThread(String name, Table table, long seed){
        super(name);
        
        this.table=table;
        this.random = new Random(seed);
    }

    @Override
    public void run() {
        try{
            while(true){
                Thread.sleep(random.nextInt(1000));
                
                String cake = "[cake no. " + nextId() + ", by " + getName() + "]";
                table.put(cake);
            }
        }catch(InterruptedException e){
            e.printStackTrace();
        }
    }
    
    public static synchronized int nextId(){
        return id++;
    }
}

class TakerThread extends Thread{
    private final Random random;
    private final Table table;
    
    public TakerThread(String name, Table table, long seed){
        super(name);
        
        this.table =table;
        this.random = new Random(seed);
    }

    @Override
    public void run() {
        try{
            while(true){
                String cake = table.take();
                Thread.sleep(random.nextInt(1000));
            }
        }catch(InterruptedException e){
            e.printStackTrace();
        }
    }
}

class Table{
    private final String[] buffer;
    
    private int tail;
    private int head;
    private int count;
    
    public Table(int count){
        buffer = new String[count];
        this.head=0;
        this.tail=0;
        this.count=0;
    }
    
    public synchronized void put(String cake) {
        System.out.println(Thread.currentThread().getName() + " puts " + cake);
        while (count >= buffer.length) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        
        buffer[tail] = cake;
        tail = (tail + 1) % buffer.length;
        count++;

        notify();
    }

    public synchronized String take() {
        while (count <= 0) {
            try {
                wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        String cake = buffer[head];
        head = (head + 1) % buffer.length;
        count--;
        notify();

        System.out.println(Thread.currentThread().getName() + " take " + cake);

        return cake;
    }
}