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Commit 8904d33

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author
ymm
committed
2015年12月14日20 提交
1 parent 8146b10 commit 8904d33

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‎ThreadStudy/src/com/xiaoyang/thread/CachedData.java‎

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package com.xiaoyang.thread;
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import java.util.concurrent.locks.ReentrantReadWriteLock;
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class CachedData {
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// 缓存对象
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Object data;
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// 缓存对象是否有值
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volatile boolean cacheValid;
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// ReadWirteLock对象
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ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
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void processCachedData() {
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//多个线程来读取数据 上读锁 读锁是可以多个多个线程共同读的 这里加锁的目的在于防止写锁的进入。
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rwl.readLock().lock();
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//【】【】【】IF A 如果没有数据 进入写数据逻辑
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if (!cacheValid) {
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// Must release read lock before acquiring write lock
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//【】【】【】在写数据之前,先要释放读锁 然后加写锁
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rwl.readLock().unlock();
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rwl.writeLock().lock();
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// Recheck state because another thread might have acquired
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// write lock and changed state before we did.
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//【】【】【】写数据之前再次检查 缓存释放有数据，多线程下同一时间可能有多个线程进入到第一个IF判断 line17
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if (!cacheValid) {
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data = "...";
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cacheValid = true;
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}
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// Downgrade by acquiring read lock before releasing write lock
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rwl.readLock().lock();
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rwl.writeLock().unlock(); // Unlock write, still hold read
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}
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//ELSE A如果有数据 进入读数据逻辑
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// use(data); 伪代码
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//读数据结束 释放读锁
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rwl.readLock().unlock();
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}
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}

‎ThreadStudy/src/com/xiaoyang/thread/CyclicBarrierTest.java‎

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package com.xiaoyang.thread;
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import java.util.concurrent.CyclicBarrier;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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public class CyclicBarrierTest {
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public static void main(String[] args) {
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ExecutorService service = Executors.newCachedThreadPool();
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final CyclicBarrier cb = new CyclicBarrier(5);
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for(int i=0;i<5;i++){
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Runnable runnable = new Runnable(){
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public void run(){
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try {
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Thread.sleep((long)(Math.random()*10000));
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System.out.println("线程" + Thread.currentThread().getName() +
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"即将到达集合地点1，当前已有" + (cb.getNumberWaiting()+1) + "个已经到达，" + (cb.getNumberWaiting()==4?"都到齐了，继续走啊":"正在等候"));
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cb.await();
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Thread.sleep((long)(Math.random()*10000));
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System.out.println("线程" + Thread.currentThread().getName() +
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"即将到达集合地点2，当前已有" + (cb.getNumberWaiting()+1) + "个已经到达，" + (cb.getNumberWaiting()==4?"都到齐了，继续走啊":"正在等候"));
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cb.await();
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Thread.sleep((long)(Math.random()*10000));
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System.out.println("线程" + Thread.currentThread().getName() +
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"即将到达集合地点3，当前已有" + (cb.getNumberWaiting() + 1) + "个已经到达，" + (cb.getNumberWaiting()==4?"都到齐了，继续走啊":"正在等候"));
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cb.await();
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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};
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service.execute(runnable);
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}
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service.shutdown();
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}
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}

‎ThreadStudy/src/com/xiaoyang/thread/OutputTwoStr.java‎

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package com.xiaoyang.thread;
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import java.util.concurrent.locks.Lock;
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import java.util.concurrent.locks.ReentrantLock;
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/*
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*
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* Á½¸öÏß³ÌÒÀ´ÎÊä³özhangxiaoxiang lihuoming
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* Lock rlock = new ReentrantLock();
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* »òÕß
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* synchronized
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* */
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public class OutputTwoStr {
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final static Outputer outputer = new Outputer();
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public static void main(String[] args) throws InterruptedException {
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MyThreadAA a = new MyThreadAA();
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MyThreadBB b = new MyThreadBB();
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b.start();
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a.start();
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}
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static class Outputer {
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Lock rlock = new ReentrantLock();
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private void output1(String name) {
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rlock.lock();
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try {
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for (int i = 0; i < name.length(); i++) {
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System.out.print(name.charAt(i));
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}
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System.out.println("");
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} catch (Exception e) {
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e.printStackTrace();
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}finally{
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rlock.unlock();
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}
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}
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private void output2(String name) {
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rlock.lock();
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try {
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for (int i = 0; i < name.length(); i++) {
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System.out.print(name.charAt(i));
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}
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System.out.println("");
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} catch (Exception e) {
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e.printStackTrace();
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}finally{
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rlock.unlock();
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}
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}
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}
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static class MyThreadAA extends Thread {
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@Override
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public void run() {
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while (true) {
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try {
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outputer.output1("yangnn");
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Thread.sleep(20);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
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}
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static class MyThreadBB extends Thread {
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@Override
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public void run() {
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// lock.lock();
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while (true) {
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try {
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outputer.output2("menghh");
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Thread.sleep(20);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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// finally{
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// lock.unlock();
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// }
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}
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}
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}

‎ThreadStudy/src/com/xiaoyang/thread/ReadWriteLockTest.java‎

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package com.xiaoyang.thread;
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import java.util.concurrent.locks.Lock;
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import java.util.concurrent.locks.ReentrantLock;
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/*
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*
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* Á½¸öÏß³ÌÒÀ´ÎÊä³özhangxiaoxiang lihuoming
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* Lock rlock = new ReentrantLock();
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* »òÕß
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* synchronized
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* */
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public class ReadWriteLockTest {
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final static Outputer outputer = new Outputer();
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public static void main(String[] args) throws InterruptedException {
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MyThreadAA a = new MyThreadAA();
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MyThreadBB b = new MyThreadBB();
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b.start();
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a.start();
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}
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static class Outputer {
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Lock rlock = new ReentrantLock();
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private void output1(String name) {
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rlock.lock();
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try {
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for (int i = 0; i < name.length(); i++) {
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System.out.print(name.charAt(i));
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}
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System.out.println("");
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} catch (Exception e) {
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e.printStackTrace();
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}finally{
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rlock.unlock();
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}
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}
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private void output2(String name) {
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rlock.lock();
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try {
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for (int i = 0; i < name.length(); i++) {
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System.out.print(name.charAt(i));
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}
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System.out.println("");
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} catch (Exception e) {
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e.printStackTrace();
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}finally{
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rlock.unlock();
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}
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}
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}
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static class MyThreadAA extends Thread {
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@Override
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public void run() {
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while (true) {
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try {
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outputer.output1("yangnn");
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Thread.sleep(20);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
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}
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static class MyThreadBB extends Thread {
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@Override
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public void run() {
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// lock.lock();
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while (true) {
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try {
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outputer.output2("menghh");
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Thread.sleep(20);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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// finally{
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// lock.unlock();
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// }
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}
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}
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}

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