2 synchronized 和 Lock+Condtion 对比

同步两种方式：synchronized关键字            Lock 锁住

package Test;import java.util.concurrent.locks.Condition;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;/* * 一个线程打印5次，另一个打印3次，交替循环3次 *  * synchronized+ this.wait()+this.notify()  *     等于Lock.lock()+unlock()+lock.newCondition()+ await()+signal() * 不同的是lock需要手动释放unlock互斥锁，而synchronized不需要 *  * mutex锁只能用于race condition不破坏critical section， * 要具体指定哪个线程访问必须有个flag，也就是这里的isOne * */public class Ex1 {public static void main(String[] args){//final Run r = new Run();final Run2 r = new Run2();new Thread(new Runnable(){@Overridepublic void run() {for(int i=0;i<3;i++)r.thread1();}}).start();new Thread(new Runnable(){public void run(){for(int i=0;i<3;i++)r.thread2();}}).start();}}class Run{private boolean isOne = true;synchronized void thread1(){while(!isOne){  //一定是循环等待，防止误唤醒try {this.wait();} catch (InterruptedException e) {e.printStackTrace();}}for(int i=1;i<=5;i++){System.out.println(Thread.currentThread().getName()+":第"+i+"次");}isOne = false;this.notify();}synchronized void thread2(){while(isOne){try{this.wait();}catch(InterruptedException e){e.printStackTrace();}}for(int i=1;i<=3;i++){System.out.println(Thread.currentThread().getName()+":第"+i+"次");}isOne = true;this.notify();} }class Run2{boolean isOne = true;Lock lock = new ReentrantLock();Condition c = lock.newCondition();void thread1(){lock.lock();try{while(!isOne){try{c.await();}catch(InterruptedException e){e.printStackTrace();}}for(int i=1;i<=5;i++)System.out.println(Thread.currentThread().getName()+":第"+i+"次");isOne = false;c.signal();}finally{lock.unlock();}}void thread2(){lock.lock();try{while(isOne){try{c.await();}catch(InterruptedException e){e.printStackTrace();}}for(int i=1;i<=3;i++)System.out.println(Thread.currentThread().getName()+":第"+i+"次");isOne = true;c.signal();}finally{lock.unlock();}}}