简单的线程池实例代码

一个简单的线程池处理，下面是创建一个线程，创建好后用ThreadPoolPhotoTool.addThreadTask()添加到线程池中执行即可

private static Runnable createParseTask(final DataSource dataSource) {
return new Runnable() {
public void run() {
//TODO thread task
}
};
}

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package com.catchdata.thread;

import java.util.LinkedList;

/**
?* A thread pool is a group of a limited number of threads that are used to execute tasks.
?*/
public class ThreadPool extends ThreadGroup {

??? private boolean isAlive;

??? private LinkedList taskQueue;

??? private int threadID;

??? private static int threadPoolID;

??? /**
??? ?* Creates a new ThreadPool.
??? ?* @param numThreads
??? ?*??????????? The number of threads in the pool.
??? ?*/
??? public ThreadPool(int numThreads) {
??? ??? super("ThreadPool-" + (threadPoolID++));
??? ??? setDaemon(true);

??? ??? isAlive = true;

??? ??? taskQueue = new LinkedList();
??? ??? for (int i = 0; i < numThreads; i++) {
??? ??? ??? new PooledThread().start();
??? ??? }
??? }
??? public int getCountOfNotRun(){
??? ??? return taskQueue.size();
??? }

??? /**
??? ?* Requests a new task to run. This method returns immediately, and the task executes on the next available idle
??? ?* thread in this ThreadPool.
??? ?* <p>
??? ?* Tasks start execution in the order they are received.
??? ?* @param task
??? ?*??????????? The task to run. If null, no action is taken.
??? ?* @throws IllegalStateException
??? ?*???????????? if this ThreadPool is already closed.
??? ?*/
??? public synchronized void runTask(Runnable task) {
??? ??? if (!isAlive) {
??? ??? ??? throw new IllegalStateException();
??? ??? }
??? ??? if (task != null) {
??? ??? ??? taskQueue.add(task);
??? ??? ??? notify();
??? ??? }

??? }

??? protected synchronized Runnable getTask() throws InterruptedException {
??? ??? while (taskQueue.size() == 0) {
??? ??? ??? if (!isAlive) {
??? ??? ??? ??? return null;
??? ??? ??? }
??? ??? ??? wait();
??? ??? }
??? ??? return (Runnable) taskQueue.removeFirst();
??? }

??? /**
??? ?* Closes this ThreadPool and returns immediately. All threads are stopped, and any waiting tasks are not executed.
??? ?* Once a ThreadPool is closed, no more tasks can be run on this ThreadPool.
??? ?*/
??? public synchronized void close() {
??? ??? if (isAlive) {
??? ??? ??? isAlive = false;
??? ??? ??? taskQueue.clear();
??? ??? ??? interrupt();
??? ??? }
??? }

??? /**
??? ?* Closes this ThreadPool and waits for all running threads to finish. Any waiting tasks are executed.
??? ?*/
??? public void join() {
??? ??? // notify all waiting threads that this ThreadPool is no
??? ??? // longer alive
??? ??? synchronized (this) {
??? ??? ??? isAlive = false;
??? ??? ??? notifyAll();
??? ??? }

??? ??? // wait for all threads to finish
??? ??? Thread[] threads = new Thread[activeCount()];
??? ??? int count = enumerate(threads);
??? ??? for (int i = 0; i < count; i++) {
??? ??? ??? try {
??? ??? ??? ??? threads[i].join();
??? ??? ??? } catch (InterruptedException ex) {
??? ??? ??? }
??? ??? }
??? }

??? /**
??? ?* A PooledThread is a Thread in a ThreadPool group, designed to run tasks (Runnables).
??? ?*/
??? private class PooledThread extends Thread {

??? ??? public PooledThread() {
??? ??? ??? super(ThreadPool.this, "PooledThread-" + (threadID++));
??? ??? }

??? ??? public void run() {
??? ??? ??? while (!isInterrupted()) {

??? ??? ??? ??? // get a task to run
??? ??? ??? ??? Runnable task = null;
??? ??? ??? ??? try {
??? ??? ??? ??? ??? task = getTask();
??? ??? ??? ??? } catch (InterruptedException ex) {
??? ??? ??? ??? }

??? ??? ??? ??? // if getTask() returned null or was interrupted,
??? ??? ??? ??? // close this thread by returning.
??? ??? ??? ??? if (task == null) {
??? ??? ??? ??? ??? return;
??? ??? ??? ??? }

??? ??? ??? ??? // run the task, and eat any exceptions it throws
??? ??? ??? ??? try {
??? ??? ??? ??? ??? task.run();
??? ??? ??? ??? } catch (Throwable t) {
??? ??? ??? ??? ??? uncaughtException(this, t);
??? ??? ??? ??? }
??? ??? ??? }
??? ??? }
??? }
}

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package com.catchdata.thread.task;

import com.catchdata.thread.ThreadPool;

public class ThreadPoolPhotoTool {

??? private static ThreadPool threadPool;

??? static {
??? ??? // thread count
??? ??? int numThreads = 3;
??? ??? // create the thread pool
??? ??? threadPool = new ThreadPool(numThreads);
??? }

??? public static void closeThreadPool() {
??? ??? // close the pool and wait for all tasks to finish.
??? ??? threadPool.join();
??? }

??? public static void addThreadTask(Runnable r) {
??? ??? threadPool.runTask(r);
??? }
??? public static int getCountOfNotRun(){
??? ??? return threadPool.getCountOfNotRun();
??? }

}