java5线程并发库中的工具

Shawn 原创，转载请注明！

原文地址：http://blog.csdn.net/a15874647/article/details/6443636

 

信号灯，，，Semaphore类。。它所实现的功能就类似于公共厕所，，如果有10个人同时要去上这个厕所，而厕所只有5个坑，所以一次只能进去5个人，当5个人中的任何一个离开后，其中另外等待的5个人中的1个人就可以上了！！！

如果说Semaphore类中只维护一个坑，就和synchronized互斥相似了。。。但是它比单纯的互斥要好，，它还能够恢复死锁状态。。。

 

Semaphore类中的acquire方法获得一个信号的许可！！！release方法释放一个信号的许可！！！而这两个方法可以被两个不同的线程调用。。。。

package concurrent.utils;import java.util.Random;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Semaphore;public class SemaphoreTest {public static void main(String[] args) {ExecutorService service = Executors.newFixedThreadPool(10);final Semaphore post = new Semaphore(5);for (int i = 0; i < 10; i++) {service.execute(new Runnable(){public void run(){try {post.acquire();} catch (InterruptedException e) {e.printStackTrace();}System.out.println(Thread.currentThread().getName()+"线程已进入厕所开始便便，，" +"当前厕所有："+(5-post.availablePermits())+"人在便便！！");try {Thread.sleep(new Random().nextInt(1000));} catch (InterruptedException e) {e.printStackTrace();}System.out.println(Thread.currentThread().getName()+"擦完屁股冲了水，，即将离开！！");post.release();System.out.println(Thread.currentThread().getName()+"已经离开，当前厕所有："+(5-post.availablePermits())+"人在便便！！");}});}}}

 

栅栏，，CyclicBarrier，，，多个同样任务线程的线程中的一道栅栏，，，等待其他线程都执行到此，才开始一起向下执行！！！！

 

 

package concurrent.utils;import java.util.Random;import java.util.concurrent.CyclicBarrier;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class CyclicBarrierTest {public static void main(String[] args) {ExecutorService service = Executors.newCachedThreadPool();final CyclicBarrier barrier = new CyclicBarrier(3);for (int i = 0; i < 3; i++) {service.execute(new Runnable() {@Overridepublic void run() {try {System.out.println(Thread.currentThread().getName()+ "已到达目的地一！！当前已有"+ (barrier.getNumberWaiting() + 1) + "已经到达,"+ (barrier.getNumberWaiting()==2?"人到齊了继续出发！":"开始等待！"));barrier.await();Thread.sleep(new Random().nextInt(1000));System.out.println(Thread.currentThread().getName()+ "已到达目的地二！！当前已有"+ (barrier.getNumberWaiting() + 1) + "已经到达"+ (barrier.getNumberWaiting()==2?"人到齊了继续出发！":"开始等待！"));barrier.await();Thread.sleep(new Random().nextInt(1000));System.out.println(Thread.currentThread().getName()+ "已到达目的地三！！当前已有"+ (barrier.getNumberWaiting() + 1) + "已经到达"+ (barrier.getNumberWaiting()==2?"旅途結束，愉快解散！":"开始等待！"));barrier.await();} catch (Exception e) {e.printStackTrace();}}});}}}

 

 

CountDownLatch,,,相当于一个计数器！！！可以实现线程的计数，，互相之间，，，到达某个数量，再往下执行！

 

package concurrent.utils;import java.util.Random;import java.util.concurrent.CountDownLatch;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class CountDownLatchTest {public static void main(String[] args) {ExecutorService pool = Executors.newFixedThreadPool(3);final CountDownLatch order = new CountDownLatch(1);final CountDownLatch answer = new CountDownLatch(3);for (int i = 0; i < 3; i++) {pool.execute(new Runnable(){public void run(){try {System.out.println(Thread.currentThread().getName()+"开始等待主线程命令！");Thread.sleep(new Random().nextInt(1000));order.await();System.out.println(Thread.currentThread().getName()+"接受开始命令，开始运行！");Thread.sleep(new Random().nextInt(1000));answer.countDown();System.out.println(Thread.currentThread().getName()+"运行完毕，向主线程发送运行结果！");} catch (Exception e) {e.printStackTrace();}}});}try {Thread.sleep(new Random().nextInt(1000));System.out.println(Thread.currentThread().getName()+"开始发送开始命令！");order.countDown();Thread.sleep(new Random().nextInt(1000));answer.await();System.out.println(Thread.currentThread().getName()+"所有线程运行结果接受完毕，准备退出！！");} catch (Exception e) {e.printStackTrace();}pool.shutdown();}}

 

 

Exchanger，，，实现两个线程之间的数据交换！！！通过exchange方法，提交数据，，，返回值为交换后得到的数据！！！

就像两个情报员互相交换数据一样，，其中一个到了，，另一个没到，，到的那个就会开始等待，等待没到的到了就进行交换。。。

 

package concurrent.utils;import java.util.concurrent.Exchanger;public class ExChangerTest {public static void main(String[] args) {final Exchanger<String> exchanger = new Exchanger<String>();new Thread(){public void run(){String data1 = "firstdata";System.out.println(Thread.currentThread().getName()+"拿着数据："+data1+"，开始准备交换数据！");try {Thread.sleep(10000);String data2 = exchanger.exchange(data1);System.out.println("交换数据成功！！");System.out.println(Thread.currentThread().getName()+"获得数据："+data2);} catch (InterruptedException e) {e.printStackTrace();}}}.start();new Thread(){public void run(){String data1 = "seconddata";System.out.println(Thread.currentThread().getName()+"拿着数据："+data1+"，开始准备交换数据！");try {Thread.sleep(10000);String data2 = exchanger.exchange(data1);System.out.println("交换数据成功！！");System.out.println(Thread.currentThread().getName()+"获得数据："+data2);} catch (InterruptedException e) {e.printStackTrace();}}}.start();}}