一、定義
Producer-Consumer Pattern就是生產(chǎn)者-消費者模式聪姿。
生產(chǎn)者和消費者在為不同的處理線程咳燕，生產(chǎn)者必須將數(shù)據(jù)安全地交給消費者，消費者進(jìn)行消費時招盲，如果生產(chǎn)者還沒有建立數(shù)據(jù)曹货，則消費者需要等待。
一般來說玩般，可能存在多個生產(chǎn)者和消費者礼饱，不過也有可能生產(chǎn)者和消費者都只有一個，當(dāng)雙方都只有一個時匀伏，我們也稱之為Pipe Pattern蝴韭。

二榄鉴、模式案例
該案例中蛉抓，定義了3個角色：廚師、客人剃诅、桌子巷送。

廚師（生產(chǎn)者）定義：

public class MakerThread extends Thread {
    private final Random random;
    private final Table table;
    private static int id = 0;     //蛋糕的流水號(所有廚師共通)
    public MakerThread(String name, Table table, long seed) {
        super(name);
        this.table = table;
        this.random = new Random(seed);
    }
    public void run() {
        try {
            while (true) {
                Thread.sleep(random.nextInt(1000));
                String cake = "[ Cake No." + nextId() + " by " + getName() + " ]";
                table.put(cake);
            }
        } catch (InterruptedException e) {
        }
    }
    private static synchronized int nextId() {
        return id++;
    }
}

客人（消費者）定義：

public class EaterThread extends Thread {
    private final Random random;
    private final Table table;
    public EaterThread(String name, Table table, long seed) {
        super(name);
        this.table = table;
        this.random = new Random(seed);
    }
    public void run() {
        try {
            while (true) {
                String cake = table.take();
                Thread.sleep(random.nextInt(1000));
            }
        } catch (InterruptedException e) {
        }
    }
}

桌子（隊列）定義：

public class Table {
    private final String[] buffer;
    private int tail;
    private int head;
    private int count;
 
    public Table(int count) {
        this.buffer = new String[count];
        this.head = 0;
        this.tail = 0;
        this.count = 0;
    }
    public synchronized void put(String cake) throws InterruptedException {
        System.out.println(Thread.currentThread().getName() + " puts " + cake);
        while (count >= buffer.length) {
            wait();
        }
        buffer[tail] = cake;
        tail = (tail + 1) % buffer.length;
        count++;
        notifyAll();
    }
    public synchronized String take() throws InterruptedException {
        while (count <= 0) {
            wait();
        }
        String cake = buffer[head];
        head = (head + 1) % buffer.length;
        count--;
        notifyAll();
        System.out.println(Thread.currentThread().getName() + " takes " + cake);
        return cake;
    }
}

執(zhí)行：

public class Main {
    public static void main(String[] args) {
        Table table = new Table(3);
        new MakerThread("MakerThread-1", table, 31415).start();
        new MakerThread("MakerThread-2", table, 92653).start();
        new MakerThread("MakerThread-3", table, 58979).start();
        new EaterThread("EaterThread-1", table, 32384).start();
        new EaterThread("EaterThread-2", table, 62643).start();
        new EaterThread("EaterThread-3", table, 38327).start();
    }
}

三、模式講解
Producer-Consumer模式的角色如下：

• Data(數(shù)據(jù))參與者
  Data代表了實際生產(chǎn)或消費的數(shù)據(jù)综苔。
• Producer(生產(chǎn)者)參與者
  Producer會創(chuàng)建Data惩系，然后傳遞給Channel參與者。
• Consumer(消費者)參與者
  Consumer從Channel參與者獲取Data數(shù)據(jù)如筛，進(jìn)行處理堡牡。
• Channel(通道)參與者
  Channel從Producer參與者處接受Data參與者，并保管起來杨刨，并應(yīng)Consumer參與者的要求晤柄，將Data參與者傳送出去。為確保安全性芥颈，Producer參與者與Consumer參與者要對訪問共享互斥。