import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class MyThreadPool {
private ExecutorService exe;
private static final int POOL_SIZE = 4;
public MyThreadPool() {
exe = Executors.newFixedThreadPool(POOL_SIZE);
}
public void doTask() {
int i = 0;
while (i < 50) {
exe.execute(new MyThread(i, exe));
i++;
}
}
class MyThread implements Runnable
{
int id;
ExecutorService exe;
MyThread(int id, ExecutorService exe) {
this.exe = exe;
this.id = id;
}
public void run() {
System.out.println(id + "start");
try {
Thread.sleep(5000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(id + "pass 5 second");
System.out.println("exe info:" + exe.toString());
try {
Thread.sleep(5000L);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(id + "end");
}
}
public static void main(String[] args) {
new MyThreadPool().doTask();
}
}
MyThreadPool为线程池管理类
MyThread为实际需要运行的线程类
运行log如下（一小部分）：
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<span style="font-size:18px;">1start 2start 3start 0start 2pass 5 second exe info:java.util.concurrent.ThreadPoolExecutor@39890510[Running, pool size = 4, active threads = 4, queued tasks = 46, completed tasks = 0] 0pass 5 second exe info:java.util.concurrent.ThreadPoolExecutor@39890510[Running, pool size = 4, active threads = 4, queued tasks = 46, completed tasks = 0] 3pass 5 second exe info:java.util.concurrent.ThreadPoolExecutor@39890510[Running, pool size = 4, active threads = 4, queued tasks = 46, completed tasks = 0] 1pass 5 second exe info:java.util.concurrent.ThreadPoolExecutor@39890510[Running, pool size = 4, active threads = 4, queued tasks = 46, completed tasks = 0] 2end 4start 0end 5start 3end 6start 1end 7start </span>
可以看到当前在运行的线程只有前4个，队列中有46个任务在等待
只要有一个线程结束立即就会执行队列中的下一个线程
