import java.util.VecTor;import java.net.*;import java.io.*;public class ThreadPool {public static final int MAX_THREADS = 100;public static final int MAX_SPARE_THREADS = 50;public static final int MIN_SPARE_THREADS = 10;public static final int WORK_WAIT_TIMEOUT = 60 * 1000;protected VecTor pool; //存放空闲线程protected MoniTorRunnable moniTor; //A moniTor thread that moniTors the pool for idel threads.protected int maxThreads; //Max number of threads that you can open in the pool.protected int minSpareThreads; //Min number of idel threads that you can leave in the pool.protected int maxSpareThreads; //Max number of idel threads that you can leave in the pool.protected int currentThreadCount; //Number of threads in the pool.protected int currentThreadsBusy; //Number of busy threads in the pool.protected boolean stopThePool; //Flag that the pool should terminate all the threads and stop./*** Construct*/public ThreadPool() {maxThreads = MAX_THREADS;maxSpareThreads = MAX_SPARE_THREADS;minSpareThreads = MIN_SPARE_THREADS;currentThreadCount = 0;currentThreadsBusy = 0;stopThePool = false;}/*** 启动线程池*/public synchronized void start() {adjustLimits(); //调整最大和最小线程数及最大和最小多余线程数.openThreads(minSpareThreads); //打开初始线程moniTor = new MoniTorRunnable(this); //Runnable对象实例 //A moniTor thread that moniTors the pool for idel threads.}public void setMaxThreads(int maxThreads) {this.maxThreads = maxThreads;}public int getMaxThreads() {return maxThreads;}public void setMinSpareThreads(int minSpareThreads) {this.minSpareThreads = minSpareThreads;}public int getMinSpareThreads() {return minSpareThreads;}public void setMaxSpareThreads(int maxSpareThreads) {this.maxSpareThreads = maxSpareThreads;}public int getMaxSpareThreads() {return maxSpareThreads;}/*** 线程池管理方法.* 当空闲队列线程中没有空闲线程时,则增加处理(空闲)线程数量.* 如果线程数量已达到最大线程数,则新的连接进行等待.* 当请求到来,且有空闲线程时调用处理线程进行具体业务处理.* @param r ThreadPoolRunnable*/public void runIt(Socket cs) { //r 为task //有任务进入时调用if (null == cs) {throw new NullPointerException();}if (0 == currentThreadCount || stopThePool) {throw new IllegalStateException();}ControlRunnable c = null; //任务处理实例.synchronized (this) {if (currentThreadsBusy == currentThreadCount) { //如果工作线程和当前线程数相等,说明没有空闲线程.if (currentThreadCount < maxThreads) { //如果当前线程数还没有达到最大线程数.int toOpen = currentThreadCount + minSpareThreads; //再增加minSpareThreads个线程量.openThreads(toOpen); //打开线程新增空闲线程. //currentThreadCount数量增加}else { //如果当前数量达到了最大线程数.while (currentThreadsBusy == currentThreadCount) { //当工作线程和当前线程数相等,说明没有空闲线程.try {this.wait(); //连接线程进行等待.}catch (InterruptedException e) {}if (0 == currentThreadCount || stopThePool) {throw new IllegalStateException();}}}}c = (ControlRunnable) pool.lastElement(); //在有空闲线程的情况下,从空闲线程队列中取出最后一个线程.pool.removeElement(c); //从空闲队列中删除最后一个线程,用于处理其他事件.currentThreadsBusy++; //对处理事件的线程数加1}System.out.println("系统调用一个Sokcet线程");c.runIt(cs); //调用具体业务方法,告诉其有数据请求要处理,唤醒等待中的线程.}/*** 关闭线程池*/public synchronized void shutdown() {if (!stopThePool) { //如果线程池没有关闭,(线程池关闭标识为假)stopThePool = true;moniTor.terminate(); //关闭监视线程moniTor = null;for (int i = 0; i maxSpareThreads) { //如果空闲的线程数大于多余的最大线程数量.int toFree = currentThreadCount - currentThreadsBusy - maxSpareThreads; //得出多余的线程数量for (int i = 0; i < toFree; i++) { //关闭删除空闲线程,从VecTor中删除ControlRunnable c = (ControlRunnable) pool.firstElement();pool.removeElement(c);c.terminate(); //让删除的线程结束currentThreadCount--; //处理线程队列减少一个}}}/*** 当线程处理完成后重新放到空闲线程队列中.* @param c ControlRunnable*/protected synchronized void returnController(ControlRunnable c) {if (0 == currentThreadCount || stopThePool) { //如果线程池关闭或当前连接线程数量为0c.terminate(); //关闭当前线程.return;}currentThreadsBusy--; //处理线程队列的数量减少一个pool.addElement(c); //空闲线程队列中增加一个notifyAll(); //唤醒可能在等待连接的线程.}/*** 当一个处理线程出现异常时,要重新开启一个空闭线程.,并唤醒在等待空闲线程的线程.ThreadPool的runIt中等待的线程.*/protected synchronized void notifyThreadEnd() {currentThreadsBusy--; //因从线程是在处理数据时出现异常,所处理线程队列的数量要减一个.currentThreadCount--; //因出现异常的线程关闭了.所开户线程的数量要减少一个.notifyAll(); //唤醒等待连接的阻塞线程.openThreads(minSpareThreads); //重新打开minSpareThreads个线程.如currentThreadCount的数量大于minSpareThreads,则还是不开启新线程.}/*** 调整各种线程队列数量*/protected void adjustLimits() {if (maxThreads = maxThreads) { //如果最大多余线程数大于最大线程数.maxSpareThreads = maxThreads; //设置最大多余线程数为最大线程数.}if (maxSpareThreads maxSpareThreads) { //如果最小多余线程大于最大多余线程数minSpareThreads = maxSpareThreads; //设置最小多余线程数为最大多余线程数.}if (minSpareThreads maxThreads) {toOpen = maxThreads;}if (0 == currentThreadCount) { //如果当前线程池中的线程数量为0pool = new VecTor(toOpen); //创建一个有minSpareThreads数量的VecTor}//因第二次增加时对第一次增加的线程不能重复增加.所要从currentThreadCount开始.for (int i = currentThreadCount; i < toOpen; i++) { //先增加minSparethreads数量的线程.pool.addElement(new ControlRunnable(this)); //Runnable实例对象,可用于创建线程}currentThreadCount = toOpen;}/*** 监视线程,用于监听当前空闲线程是否大于最大多余线程数量,如存在则关闭多余的空闲线程.*/class MoniTorRunnableimplements Runnable {ThreadPool p;Thread t;boolean shouldTerminate;/*** construct* @param p ThreadPool*/MoniTorRunnable(ThreadPool p) {shouldTerminate = false;this.p = p;t = new Thread(this);t.start();}public void run() {while (true) {try {synchronized (this) {this.wait(WORK_WAIT_TIMEOUT);}if (shouldTerminate) { //如果结束break;}p.checkSpareControllers(); //检查是否有多余线程.}catch (Throwable t) {t.printStackTrace();}}}public void stop() {this.terminate();}public synchronized void terminate() {shouldTerminate = true;this.notifyAll();}}}
困难与折磨对于人来说，是一把打向坯料的锤，
