Java线程池介绍和实例 _Java线程池

Java线程池表示一组正在等待作业并多次重复使用的工作线程。
如果是线程池, 则会创建一组固定大小的线程。服务提供商从线程池中拉出一个线程并为其分配作业。作业完成后, 线程再次包含在线程池中。
Java线程池的优势更好的性能由于无需创建新线程, 因此可以节省时间。
实时使用它用于Servlet和JSP, 其中容器创建线程池来处理请求。
Java线程池示例让我们来看一个使用ExecutorService和Executors的Java线程池的简单示例。
【Java线程池介绍和实例】文件：WorkerThread.java

import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; class WorkerThread implements Runnable { private String message; public WorkerThread(String s){ this.message=s; } public void run() { System.out.println(Thread.currentThread().getName()+" (Start) message = "+message); processmessage(); //call processmessage method that sleeps the thread for 2 seconds System.out.println(Thread.currentThread().getName()+" (End)"); //prints thread name } private void processmessage() { try {Thread.sleep(2000); } catch (InterruptedException e) { e.printStackTrace(); } } }

文件：JavaThreadPoolExample.java

public class TestThreadPool { public static void main(String[] args) { ExecutorService executor = Executors.newFixedThreadPool(5); //creating a pool of 5 threads for (int i = 0; i < 10; i++) { Runnable worker = new WorkerThread("" + i); executor.execute(worker); //calling execute method of ExecutorService } executor.shutdown(); while (!executor.isTerminated()) {}System.out.println("Finished all threads"); } }

输出：

pool-1-thread-1 (Start) message = 0 pool-1-thread-2 (Start) message = 1 pool-1-thread-3 (Start) message = 2 pool-1-thread-5 (Start) message = 4 pool-1-thread-4 (Start) message = 3 pool-1-thread-2 (End) pool-1-thread-2 (Start) message = 5 pool-1-thread-1 (End) pool-1-thread-1 (Start) message = 6 pool-1-thread-3 (End) pool-1-thread-3 (Start) message = 7 pool-1-thread-4 (End) pool-1-thread-4 (Start) message = 8 pool-1-thread-5 (End) pool-1-thread-5 (Start) message = 9 pool-1-thread-2 (End) pool-1-thread-1 (End) pool-1-thread-4 (End) pool-1-thread-3 (End) pool-1-thread-5 (End) Finished all threads