如何去设计一个自己的线程池？ 思路与生产者与消费者模式相同，将任务放到队列中，子线程再从队列中取出任务去执行。
方式一：固定线程池，一开始是就申请好线程。
比如：
公司一次性雇佣5个工人，往后在接手任务还是这5 个人去做。
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
public class ThreadPoolV1{
private BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<>(10);//队列容量为10，大于就阻塞等待。
private Thread[] workers = new Thread[5];//线程的个数即一开始雇佣的工人个数
ThreadPoolV1() {
for (int i = 0; i < 5; i++) {
workers[i] = new Worker(workQueue);
workers[i].start();//5个线程的启动 去完成业务
}
}
public void execute(Runnable cmd) throws InterruptedException {
workQueue.put(cmd);//将任务放到队列中
}
private static class Worker extends Thread {
private BlockingQueue<Runnable> workQueue;
Worker(BlockingQueue<Runnable> queue) {
workQueue = queue;
}
@Override
public void run() {
while (!isInterrupted()) {
try {
Runnable cmd = workQueue.take();//从队列中把任务取出来
cmd.run();//业务
} catch (InterruptedException e) {
break;
}
}
}
}
public static void main(String[] args) throws InterruptedException {
ThreadPoolV1 pool = new ThreadPoolV1();
pool.execute(new Runnable() {
@Override
public void run() {
while (true) {
System.out.println("第一个事情");
}
}
});
pool.execute(new Runnable() {
@Override
public void run() {
while (true) {
System.out.println("第二个时期");
}
}
});
pool.execute(new Runnable() {
@Override
public void run() {
while (true) {
System.out.println("第三 个时期");
}
}
});
pool.execute(new Runnable() {
@Override
public void run() {
while (true)
System.out.println("第四个时期");
}
}
});
pool.execute(new Runnable() {
@Override
public void run() {
while (true) {
System.out.println("第五个时期");
}
}
});
pool.execute(new Runnable() {
@Override
public void run() {
while (true) {
System.out.println("第五个时期");
}
}
});
}
```
```
方式二：当有任务时雇佣一个工人，再来任务时再雇佣一个工人，一直这样，直到雇佣人数达到预期最大值，再来任务就放到队列中去。
public class ThreadPoolV2 { private BlockingQueue<Runnable> workQueue = new ArrayBlockingQueue<>(10);//队列上大于10个任务时，发生阻塞等待 private int maxThreads = 5; private int currentThreads = 0;//一开始没有线程 private Thread[] works = new Thread[maxThreads]; public void execute(Runnable cmd) throws InterruptedException { if (currentThreads == maxThreads) {//雇佣人数达到最大值 workQueue.put(cmd);//任务放到队列 } else { Worker worker = new Worker(workQueue);//雇佣一个工人 works[currentThreads++] = worker; worker.start(); workQueue.put(cmd); } } private static class Worker extends Thread { private BlockingQueue<Runnable> workQueue; Worker(BlockingQueue<Runnable> queue) { workQueue = queue; } @Override public void run() { while (!isInterrupted()) { try { Runnable cmd = workQueue.take();//从 cmd.run(); } catch (InterruptedException e) { break; } } } } } public static void main(String[] args) throws InterruptedException { ThreadPoolV1 pool = new ThreadPoolV1(); pool.execute(new Runnable() { @Override public void run() { while (true) { System.out.println("第一个事情"); } } }); pool.execute(new Runnable() { @Override public void run() { while (true) { System.out.println("第二个时期"); } } }); pool.execute(new Runnable() { @Override public void run() { while (true) { System.out.println("第三 个时期"); } } }); pool.execute(new Runnable() { @Override public void run() { while (true) { System.out.println("第四个时期"); } } }); pool.execute(new Runnable() { @Override public void run() { while (true) { System.out.println("第五个时期"); } } }); pool.execute(new Runnable() { @Override public void run() { while (true) { System.out.println("第六个时期"); } } }); } }
