实现需求：两个线程交替打印1,0，打印10轮

java多线程口诀：

• 高内聚，低耦合
• 线程操作资源类
• 判断干活通知
• 防止虚假唤醒
  

方式一：使用synchronized和Object的wait和notifyAll方法

wait:使当前线程阻塞

notify,notifyAll唤醒当前线程

/** * 两个线程交替打印1，0 打印10轮 * * @author Administrator * @version 1.0 2020年7月12日 * @see ProdConsumerDemo1 * @since 1.0 * */class ShareData1 { public int number = 0; public synchronized void increment() throws Exception { while (number != 0) { this.wait(); } number++; System.out.println(Thread.currentThread().getName() + " " + number); this.notifyAll(); } public synchronized void decrement() throws InterruptedException { while (number != 1) { this.wait(); } number--; System.out.println(Thread.currentThread().getName() + " " + number); this.notifyAll(); }} public class ProdConsumerDemo1 { public static void main(String[] args) { ShareData1 shareData = new ShareData1(); new Thread(() -> { for (int i = 0; i < 10; i++) { try { shareData.increment(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }, "A").start(); new Thread(() -> { for (int i = 0; i < 10; i++) { try { shareData.decrement(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }, "B").start(); }}

输出结果

A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0

方式二：使用jdk1.8的Lock和Condition

class ShareData2 { private int number = 0; private Lock lock = new ReentrantLock(); private Condition condition = lock.newCondition(); public void increment() throws Exception { lock.lock(); try { while (number != 0) { condition.await(); } number++; System.out.println(Thread.currentThread().getName() + " " + number); condition.signalAll(); } finally { lock.unlock(); } } public void decrement() throws InterruptedException { lock.lock(); try { while (number != 1) { condition.await(); } number--; System.out.println(Thread.currentThread().getName() + " " + number); condition.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } }} public class ProdConsumerDemo2 { public static void main(String[] args) { ShareData2 shareData = new ShareData2(); new Thread(() -> { for (int i = 0; i < 10; i++) { try { shareData.increment(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }, "A").start(); new Thread(() -> { for (int i = 0; i < 10; i++) { try { shareData.decrement(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }, "B").start(); }}

输出结果

A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0A 1B 0

主要是熟悉Lock和Condition的使用

Lock和Condition相比于synchronized，能够精确唤醒

需求：三个线程A,B,C顺序打印，A打印5次，B打印10次，C打印15次，10轮

class ShareData3 { private int number = 1; private Lock lock = new ReentrantLock(); private Condition c1 = lock.newCondition(); private Condition c2 = lock.newCondition(); private Condition c3 = lock.newCondition(); public void print5() throws Exception { lock.lock(); try { while (number != 1) { c1.await(); } number = 2; for (int i = 0; i < 5; i++) { System.out.println(Thread.currentThread().getName() + " " + i); } c2.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } } public void print10() throws InterruptedException { lock.lock(); try { while (number != 2) { c2.await(); } number=3; for (int i = 0; i < 10; i++) { System.out.println(Thread.currentThread().getName() + " " + i); } c3.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } } public void print15() throws InterruptedException { lock.lock(); try { while (number != 3) { c3.await(); } number = 1; for (int i = 0; i < 15; i++) { System.out.println(Thread.currentThread().getName() + " " + i); } c1.signalAll(); } finally { // TODO: handle finally clause lock.unlock(); } }} public class ProdConsumerDemo3 { public static void main(String[] args) { ShareData3 shareData3 = new ShareData3(); new Thread(() -> { try { for (int i = 0; i < 10; i++) { shareData3.print5(); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }, "A").start(); new Thread(() -> { try { for (int i = 0; i < 10; i++) { shareData3.print10(); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }, "B").start(); new Thread(() -> { try { for (int i = 0; i < 10; i++) { shareData3.print15(); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }, "C").start(); }}

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