Java线程池
Java线程池代表一组正在等待作业并多次重复使用的工作线程。
在线程池的情况下，将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，因此节省了时间。
实时用法
它在Servlet和JSP中使用，其中容器创建了一个线程池来处理请求。
Java线程池示例
我们来看一个使用ExecutorService和Executors的Java线程池的简单示例。
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
