java中线程池的实现.doc

Java中线程池的实现/* Copyright: Copyright (c) 2002-2003* Company: JavaResearch()* 最后更新日期:2003年4月22日* author hijack*/import java.util.Vector;/*线程池的方法使得在线程密集的情况下原有线程得到重用*从而提高性能*since 0.6*/public class ThreadPool implements Runnable/ThreadPool里最大线程数、最少线程数、释放延时的确省值 public final static int DEFAULT_MIN_SIZE = 0; public final static int DEFAULT_MAX_SIZE = Integer.MAX_VALUE; public final static long DEFAULT_RELEASE_DELAY = 10 * 1000; /用户定制的threadpool属性值 protected int minSize; protected int maxSize; protected long releaseDelay; /ThreadPool里现有的线程数 protected int currentSize; /ThradPool里还可以提供的线程数 protected int availableThreads; /任务列表(实质意义上的线程池) protected Vector taskList; /* *用户定制的ThradPool *param minSize 线程池最少线程数 *param maxSize 线程池最多线程数 *param releaseDelay 线程释放延时 */ public ThreadPool(int minSize,int maxSize,long releaseDelay) this.minSize = minSize; this.maxSize = maxSize; this.releaseDelay = releaseDelay; taskList = new Vector(100); availableThreads = 0; /* *缺省的ThreadPool */ public ThreadPool() this(DEFAULT_MIN_SIZE,DEFAULT_MIN_SIZE,DEFAULT_RELEASE_DELAY); /* *设置线程池中最少线程数 *param minSize 线程池最少线程数 */ public synchronized void setMinSize(int minSize) this.minSize = minSize; /* *读取线程池最少线程数这一属性 */ public synchronized int getMinSize() return minSize; /* *设置线程池中最大线程数 *param maxSize 线程池最大线程数 */ public synchronized void setMaxSize(int maxSize) this.maxSize = maxSize; /* *读取线程池最大线程数这一属性 */ public synchronized int getMaxSize() return maxSize; /* *设置线程池中线程释放延时 *param releaseDelay 线程释放延时 */ public synchronized void setReleaseDelay(long releaseDelay) this.releaseDelay = releaseDelay; /* *读取线程释放延时这一属性 */ public synchronized long getReleaseDelay() return releaseDelay; /* *往ThreadPool里添加新的任务 *param runnable 新的任务 */ public synchronized void addTask(Runnable runnable) taskList.addElement(runnable); if(availableThreads 0) this.notify(); else if(currentSize maxSize) currentSize-; break; task = getNextTask(); if(task = null ) try availableThreads+; wait(releaseDelay); availableThreads-; catch(InterruptedException ie) / do something you wanna task = getNextTask(); if(task = null) if(currentSize 0) task = (Runnable)(taskList.elementAt(0); taskList.removeElementAt(0); return task; /* *返回ThreadPool的信息 */ public String toString() StringBuffer sb = new StringBuffer(); sb.append(DEFAULT_MIN_SIZE : + DEFAULT_MIN_SIZE + n); sb.append(DEFAULT_MAX_SIZE : + DEFAULT_MAX_SIZE + n); sb.append(DEFAULT_RELEASE_DELAY : + DEFAULT_RELEASE_DELAY + n ); sb.append(the information about yours construct ThreadPool be