锁框架：条件

Condition声明了下列方法：

void await(): 在接收到信号或者被中断之前，强制调用线程一直等待。

long awaitNanos(long nanosTimeout): 在接收到信号，被中断，或者超过指定的等待时间之前，强制当前线程一直等待。

boolean awaitUninterruptibly(): 在接收到信号之前，强制当前线程一直等待。

void signal(): 唤醒一个等待中的线程。

void singalAll(): 唤醒所有等待中的线程。

示例：

package com.lock;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * condition 条件
 *     接口condition把object的wait和notification方法（wait(),notify()和notifyAll()）
 * 分解到不同的条件对象中。通过把这些条件和任意的lock实现使用组合，起到让每个对象上具有多重等待集合的作用。
 * 生产者与消费者模型
 *     用lock和condition替代synchronize和等待及通知
 *     生产一个字母后消费一个字母
 * @author Administrator
 *
 */
public class PC {
    public static void main(String[] args) {
        Shared s = new Shared();
        new Producer(s).start();
        new Consumer(s).start();
    }
}

class Shared {
    private char c;

    private volatile boolean available;

    private final Lock lock;

    private final Condition condition;

    Shared() {
        available = false;  //初始化false，保证先生产再消费
        lock = new ReentrantLock();
        condition = lock.newCondition();  //获取特定lock实例的condition实例
    }

    Lock getLock() {
        return lock;
    }

    char getSharedChar() {
        lock.lock();
        try {
            while (!available){
                try {
                    condition.await();
                } catch (InterruptedException ie) {
                    ie.printStackTrace();
                }
            }
            available = false;
            condition.signal();
        } finally {
            lock.unlock();
            return c;
        }
    }

    void setSharedChar(char c) {
        lock.lock();
        try {
            while (available)
                try {
                    condition.await();
                } catch (InterruptedException ie) {
                    ie.printStackTrace();
                }
            this.c = c;
            available = true;  //生产一个后，必须先消费
            condition.signal();  //唤醒一个等待中的线程
        } finally {
            lock.unlock();
        }
    }
}

//生产者
class Producer extends Thread {
    private final Lock l;

    private final Shared s;

    Producer(Shared s) {
        this.s = s;
        l = s.getLock();
    }

    @Override
    public void run() {
        for (char ch = 'A'; ch <= 'Z'; ch++) {
            l.lock();
            s.setSharedChar(ch);
            System.out.println(ch + " produced by producer.");
            l.unlock();
        }
    }
}

//消费者
class Consumer extends Thread {
    private final Lock l;

    private final Shared s;

    Consumer(Shared s) {
        this.s = s;
        l = s.getLock();
    }

    @Override
    public void run() {
        char ch;
        do {
            l.lock();
            ch = s.getSharedChar();
            System.out.println(ch + " consumed by consumer.");
            l.unlock();
        } while (ch != 'Z');
    }
}

 传统方式实现以上代码：通过synchronize和等待及通知实现

package com.lock;

/**
 * 生产者消费者模式
 *     生产一个字母后消费一个字母
 * @author Administrator
 *
 */
public class PC2 {
    public static void main(String[] args) {
        Shared2 s = new Shared2();
        new Producer2(s).start();
        new Consumer2(s).start();
    }
}

class Shared2 {
    private char c;
    private volatile boolean writeable = true;

    synchronized void setSharedChar(char c) {
        while (!writeable)
            try {
                wait();
            } catch (InterruptedException ie) {
            }
        this.c = c;
        writeable = false;
        notify();
    }

    synchronized char getSharedChar() {
        while (writeable)
            try {
                wait();
            } catch (InterruptedException ie) {
            }
        writeable = true;
        notify();
        return c;
    }
}

class Producer2 extends Thread {
    private final Shared2 s;

    Producer2(Shared2 s) {
        this.s = s;
    }

    @Override
    public void run() {
        for (char ch = 'A'; ch <= 'Z'; ch++) {
            synchronized (s) {
                s.setSharedChar(ch);
                System.out.println(ch + " produced by producer.");
            }
        }
    }
}

class Consumer2 extends Thread {
    private final Shared2 s;

    Consumer2(Shared2 s) {
        this.s = s;
    }

    @Override
    public void run() {
        char ch;
        do {
            synchronized (s) {
                ch = s.getSharedChar();
                System.out.println(ch + " consumed by consumer.");
            }
        } while (ch != 'Z');
    }
}