终于到了真正的WorkerThread，这是真正执行任务的服务器线程：
package com.crackj2ee.thread;
public class WorkerThread extends Thread {
private static int count = 0;
private boolean busy = false;
private boolean stop = false;
private TaskQueue queue;
public WorkerThread(ThreadGroup group, TaskQueue queue) {
super(group, "worker-" + count);
count++;
this.queue = queue;
}
public void shutdown() {
stop = true;
this.interrupt();
try {
this.join();
}
catch(InterruptedException ie) {}
}
public boolean isIdle() {
return !busy;
}
public void run() {
System.out.println(getName() + " start.");
while(!stop) {
Task task = queue.getTask();
if(task!=null) {
busy = true;
task.execute();
busy = false;
}
}
System.out.println(getName() + " end.");
}
}
前面已经讲过，queue.getTask()是一个阻塞方法，服务器线程可能在此wait()一段时间。此外，WorkerThread还有一个shutdown方法，用于安全结束线程。
最后是ThreadPool，负责管理所有的服务器线程，还可以动态增加和减少线程数：
package com.crackj2ee.thread;
import java.util.*;
public class ThreadPool extends ThreadGroup {
private List threads = new LinkedList();
private TaskQueue queue;
public ThreadPool(TaskQueue queue) {
super("Thread-Pool");
this.queue = queue;
}
public synchronized void addWorkerThread() {
Thread t = new WorkerThread(this, queue);
threads.add(t);
t.start();
}
public synchronized void removeWorkerThread() {
if(threads.size()>0) {
WorkerThread t = (WorkerThread)threads.remove(0);
t.shutdown();
}
}
public synchronized void currentStatus() {
System.out.println("-----------------------------------------------");
System.out.println("Thread count = " + threads.size());
Iterator it = threads.iterator();
while(it.hasNext()) {
WorkerThread t = (WorkerThread)it.next();
System.out.println(t.getName() + ": " + (t.isIdle() ? "idle" : "busy"));
}
System.out.println("-----------------------------------------------");
}
}
currentStatus()方法是为了方便调试，打印出所有线程的当前状态。
