13.Java5条件阻塞Condition的应用

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

/**
 * Java5条件阻塞Condition的应用
 * Condition的功能类似在传统线程技术中的Object.wait()和Object.notify()功能。
 * 在等待Condition时，允许发生“虚假唤醒”，这通常作为基础平台语义的让步。对于大多数应用程序，
 * 这带来的实际影响很小，因为Condition应该总是在一个循环中被等待，并测试正被等待的状态声明。
 * 某个实现可以随意溢出可能的虚假唤醒，但建议应用程序员总是假定这些虚假唤醒可能发生，因此总是在一个循环中等待。
 * 
 * 一个锁内部可以有多个Condition，即有多个
 * 
 * Condition是基于Lock之上的
 * @author LiTaiQing
 *
 */
public class ConditionCommunication {

    public static void main(String[] args) {
        final Business business = new Business();
        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 1; i <= 50; i++) {
                    business.sub(i);
                }

            }
        }).start();

        for (int i = 1; i <= 50; i++) {
            business.main(i);
        }

    }

    static class Business {
        Lock lock = new ReentrantLock();
        Condition condition = lock.newCondition();
        private boolean bShouldSub = true;

        public void sub(int i) {
            lock.lock();
            try {
                while (!bShouldSub) {
                    try {
                        condition.await();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                for (int j = 1; j <= 10; j++) {
                    System.out.println("sub thread sequence of " + j
                            + ",loop of " + i);
                }
                bShouldSub = false;
                condition.signal();
            } finally {
                lock.unlock();
            }
        }

        public void main(int i) {
            lock.lock();
            try {
                while (bShouldSub) {
                    try {
                        condition.await();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                for (int j = 1; j <= 100; j++) {
                    System.out.println("main thread sequence of " + j
                            + ",loop of " + i);
                }
                bShouldSub = true;
                condition.signal();
            } finally {
                lock.unlock();
            }
        }
    }
}

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

public class ThreeConditionCommunication {
    public static void main(String[] args) {
        final Business business = new Business();
        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 1; i <= 50; i++) {
                    business.sub2(i);
                }

            }
        }).start();
        new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 1; i <= 50; i++) {
                    business.sub3(i);
                }

            }
        }).start();
        for (int i = 1; i <= 50; i++) {
            business.main(i);
        }

    }

    static class Business {
        Lock lock = new ReentrantLock();
        Condition condition1 = lock.newCondition();
        Condition condition2 = lock.newCondition();
        Condition condition3 = lock.newCondition();
        private int shouldSub = 1;
        public void sub2(int i) {
            lock.lock();
            try {
                while (shouldSub != 2) {
                    try {
                        condition2.await();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                for (int j = 1; j <= 10; j++) {
                    System.out.println("sub2 thread sequence of " + j
                            + ",loop of " + i);
                }
                shouldSub = 3;
                condition3.signal();
            } finally {
                lock.unlock();
            }
        }

        public void sub3(int i) {
            lock.lock();
            try {
                while (shouldSub != 3) {
                    try {
                        condition3.await();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                for (int j = 1; j <= 20; j++) {
                    System.out.println("sub3 thread sequence of " + j
                            + ",loop of " + i);
                }
                shouldSub = 1;
                condition1.signal();
            } finally {
                lock.unlock();
            }
        }

        public void main(int i) {
            lock.lock();
            try {
                while (shouldSub != 1) {
                    try {
                        condition1.await();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                for (int j = 1; j <= 100; j++) {
                    System.out.println("main thread sequence of " + j
                            + ",loop of " + i);
                }
                shouldSub = 2;
                condition2.signal();
            } finally {
                lock.unlock();
            }
        }

    }
}