Java實現(xiàn)通用線程池

1、Java實現(xiàn)通用線程池線程池通俗的描述就是預(yù)先創(chuàng)建若干空閑線程，等到需要用多線程去處理事務(wù)的時候去喚醒某些空閑線程執(zhí)行處理任務(wù)，這樣就省去了頻繁創(chuàng)建線程的時間，因為頻 繁創(chuàng)建線程是要耗費大量的CPU資源的。如果一個應(yīng)用程序需要頻繁地處理大量并發(fā)事務(wù)，不斷的創(chuàng)建銷毀線程往往會大大地降低系統(tǒng)的效率，這時候線程池就派 上用場了。本文旨在使用Java語言編寫一個通用的線程池。當需要使用線程池處理事務(wù)時，只需按照指定規(guī)范封裝好事務(wù)處理對象，然后用已有的線程池對象去自動選擇空 閑線程自動調(diào)用事務(wù)處理對象即可。并實現(xiàn)線程池的動態(tài)修改（修改當前線程數(shù)，最大線程數(shù)等）。下面是實現(xiàn)代碼：/ThreadTask .

2、javapackage polarman.threadpool;/* 線程任務(wù)* author ryang* 2006-8-8*/public interface ThreadTask public void run(;/PooledThread.javapackage polarman.threadpool;/* 接受線程池管理的線程* author ryang* 2006-8-8*/public class PooledThread extends Thread protected Vector tasks = new Vector(;protected boolean running =

3、 false;protected boolean stopped = false;protected boolean paused = false;protected boolean killed = false;private ThreadPool pool;public PooledThread(ThreadPool poolthis.pool = pool;public void putTask(ThreadTask tasktasks.add(task;public void putTasks(ThreadTask tasksfor(int i=0; i public void put

4、Tasks(Collection tasksprotected ThreadTask popTask(if(tasks.size( > 0return (ThreadTasktasks.remove(0;elsereturn null;public boolean isRunning(return running;public void stopTasks(stopped = true;public void stopTasksSync(stopTasks(;while(isRunning(try sleep(5; catch (InterruptedException e public

5、 void pauseTasks(paused = true;public void pauseTasksSync(pauseTasks(;while(isRunning(try sleep(5; catch (InterruptedException e public void kill(if(!runninginterrupt(;elsekilled = true;public void killSync(kill(;while(isAlive(try sleep(5; catch (InterruptedException e public synchronized void start

6、Tasks(running = true;this.notify(;public synchronized void run(trywhile(trueif(!running | tasks.size( = 0pool.notifyForIdleThread(;this.wait(;elseThreadTask task;while(task = popTask( != nulltask.run(;if(stoppedstopped = false;if(tasks.size( > 0tasks.clear(;break;if(pausedpaused = false;if(tasks.

7、size( > 0break;running = false;if(killedkilled = false;break;catch(InterruptedException ereturn;/ThreadPool.javapackage polarman.threadpool;/* 線程池* author ryang* 2006-8-8*/public class ThreadPool protected int maxPoolSize;protected int initPoolSize;protected Vector threads = new Vector(;protected

8、 boolean initialized = false;protected boolean hasIdleThread = false;public ThreadPool(int maxPoolSize, int initPoolSizethis.maxPoolSize = maxPoolSize;this.initPoolSize = initPoolSize;public void init(initialized = true;for(int i=0; i PooledThread thread = new PooledThread(this;thread.start(;threads

9、.add(thread;public void setMaxPoolSize(int maxPoolSizethis.maxPoolSize = maxPoolSize;if(maxPoolSize < getPoolSize(setPoolSize(maxPoolSize;/* 重設(shè)當前線程數(shù)* 若需殺掉某線程，線程不會立刻殺掉，而會等到線程中的事務(wù)處理完成* 但此方法會立刻從線程池中移除該線程，不會等待事務(wù)處理結(jié)束* param size*/public void setPoolSize(int sizeif(!initializedinitPoolSize = size;retur

10、n;else if(size > getPoolSize(for(int i=getPoolSize(; i PooledThread thread = new PooledThread(this;thread.start(;threads.add(thread;else if(size < getPoolSize(while(getPoolSize( > sizePooledThread th = (PooledThreadthreads.remove(0;th.kill(;public int getPoolSize(return threads.size(;protec

11、ted void notifyForIdleThread(hasIdleThread = true;protected boolean waitForIdleThread(hasIdleThread = false;while(!hasIdleThread && getPoolSize( >= maxPoolSizetry Thread.sleep(5; catch (InterruptedException e return false;return true;public synchronized PooledThread getIdleThread(while(tr

12、uefor(Iterator itr=threads.iterator(; itr.hasNext(;PooledThread th = (PooledThreaditr.next(;if(!th.isRunning(return th;if(getPoolSize( < maxPoolSizePooledThread thread = new PooledThread(this;thread.start(;threads.add(thread;return thread;if(waitForIdleThread( = falsereturn null;public void proce

13、ssTask(ThreadTask taskPooledThread th = getIdleThread(;if(th != nullth.putTask(task;th.startTasks(;public void processTasksInSingleThread(ThreadTask tasksPooledThread th = getIdleThread(;if(th != nullth.putTasks(tasks;th.startTasks(;public void processTasksInSingleThread(Collection tasksPooledThread

14、 th = getIdleThread(;if(th != nullth.putTasks(tasks;th.startTasks(;下面是線程池的測試程序/ThreadPoolTest.javapublic class ThreadPoolTest public static void main(String args final ThreadPool pool = new ThreadPool(3, 2;pool.init(;Thread cmdThread = new Thread(public void run(BufferedReader reader = new BufferedR

15、eader(new InputStreamReader(System.in;while(truetry String line = reader.readLine(;String words = line.split(" "if(words0.equalsIgnoreCase("quit"System.exit(0;else if(words0.equalsIgnoreCase("size" && words.length >= 2tryint size = Integer.parseInt(words1;poo

16、l.setPoolSize(size;catch(Exception eelse if(words0.equalsIgnoreCase("max" && words.length >= 2tryint max = Integer.parseInt(words1;pool.setMaxPoolSize(max;catch(Exception eelse if(words0.equalsIgnoreCase("task" && words.length >= 3tryint timelen = Integer.pa

17、rseInt(words2;SimpleTask task = new SimpleTask(words1, timelen * 1000;cessTask(task;catch(Exception e catch (IOException e e.printStackTrace(;cmdThread.start(;/*for(int i=0; i<10; i+SimpleTask task = new SimpleTask("Task" + i, (i+10*1000;cessTask(task;*/class SimpleTask implements ThreadTaskprivate String taskName;private int timeLen;public SimpleTask(String taskName, int timeLenthis.taskName = taskName;this.timeLen = timeLen;public void run( ": START TASK "" + taskName + """try Thread.sleep(timeLen;