ThreadPool的实现
最近看hadoop的时候，无意中看到了concurrent包中的类，于是打算好好研究一下线程安全方面的东西。先自己实现一个线程池。然后和sun自带的threadpool比较一下，看自己的实现有什么问题。
?1. ThreadPool 类，用于存储工作线程，在构造函数中创建线程，并启动线程
package com.fnk.threadpool;import java.util.Vector;public class ThreadPool {private Vector<Thread> threads;private static final int DEFAULT_THREAD_SIZE = 5;ThreadPool(ThreadWorkQueue workQueue) throws InvalidThreadParamException{this(workQueue,DEFAULT_THREAD_SIZE);}ThreadPool(ThreadWorkQueue workQueue,int threadSize) throws InvalidThreadParamException{if(workQueue == null || threadSize <= 0){throw new InvalidThreadParamException();}this.threads = new Vector<Thread>();for(int i = 0 ; i < threadSize; i++){threads.add(new WorkThread(workQueue));threads.get(i).start();}}}?
?2.任务队列类
package com.fnk.threadpool;import java.util.Vector;/* * 任务队列类，用于存储任务。先到的任务，先执行 */public class ThreadWorkQueue {private Vector<WorkIntf> works;public Object mutex = new Object(); ThreadWorkQueue(){works = new Vector<WorkIntf>();}/* * 任务进队列，如果原来的队列中的任务数为0，唤醒任务线程 */public void enQueue(WorkIntf work){if(works.size() == 0){works.add(work);synchronized (mutex) {mutex.notifyAll();}}else{works.add(work);}}/* * 任务出队列，如果队列中的任务数为0，让线程等待 */public WorkIntf deQueue(){if(works.size() == 0){synchronized (mutex) {try {mutex.wait();} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}return null;}else{return works.remove(0);}}}?
?3.任务接口类
package com.fnk.threadpool;public interface WorkIntf {public boolean doWork();}?4. 工作线程类
package com.fnk.threadpool;//任务线程类 public class WorkThread extends Thread {ThreadWorkQueue workQueue;WorkThread(ThreadWorkQueue workQueue) {this.workQueue = workQueue;}public void run() {while (true) {WorkIntf work = null;//获取任务，如果任务队列中，work = workQueue.deQueue();//如果 有任务 ，那么就工作 if (work != null) {work.doWork();}}}}?? 5. 异常类
package com.fnk.threadpool;public class InvalidThreadParamException extends Exception {/** * */private static final long serialVersionUID = 1L;public InvalidThreadParamException() {super();}public InvalidThreadParamException(String message) {super(message);}public InvalidThreadParamException(String message, Throwable cause) {super(message, cause);}public InvalidThreadParamException(Throwable cause) {super(cause);}}? 6. 测试
package com.fnk.threadpool;public class TestThreadPool {public static void main(String[] args) {try {ThreadWorkQueue workQueue = new ThreadWorkQueue();ThreadPool tp = new ThreadPool(workQueue);for(int i = 0; i < 10 ; i++){workQueue.enQueue(new WorkImpl(i));}} catch (InvalidThreadParamException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}?
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?总结：缺点是不能动态的控制线程的个数，在线程池开启的时候就必须创建所以线程。