线程池相关API
- JDK 5.0起提供了线程池相关API:ExecutorService和 Executors
- ExecutorService:真正的线程池接口。常见子类ThreadPoolExecutor
- void execute(Runnable command):执行任务/命令,没有返回值,一般用来执行Runnable
- <T> Future<T> submit(Callable<T> task):执行任务,有返回值,一般用来执行Callable
- void shutdown():关闭连接池
- Executors:工具类、线程池的工厂类,用于创建并返回不同类型的线程池
- Executors.newCachedThreadPool():创建一个可根据需要创建新线程的线程池
- Executors.newFixedThreadPool(n);创建一个可重用固定线程数的线程池
- Executors.newSingleThreadExecutor():创建一个只有一个线程的线程池
- Executors.newScheduledThreadPool(n):创建一个线程池,它可安排在给定延迟后运行命令或者定期地执行。
没有返回值,一般用来执行Runnable示例:
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
class NumberThread implements Runnable {
@Override
public void run() {
// 遍历100以内的偶数
for (int i = 0; i < 100; i++) {
if (i % 2 == 0) {
System.out.println(Thread.currentThread().getName() + ":" + i);
}
}
}
}
public class ThreadPool {
public static void main(String[] args) {
// 1.提供指定线程数量的线程池
ExecutorService service = Executors.newFixedThreadPool(10);
// 2.执行指定的线程的操作。需要提供实现Runnable接口的对象
service.execute(new NumberThread());// 适合用于Runnable// 3.关闭连接池
service.shutdown();
}
}
有返回值,一般用来执行Callable示例:
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
class NumberThread implements Callable {
@Override
public Object call() throws Exception {
int sum = 0;
// 遍历100以内的偶数
for (int i = 0; i < 100; i++) {
if (i % 2 == 0) {
System.out.println(Thread.currentThread().getName() + ":" + i);
sum += i;
}
}
return sum;
}
}
public class ThreadPool {
public static void main(String[] args) {
// 1.提供指定线程数量的线程池
ExecutorService service = Executors.newFixedThreadPool(10);
// 2.执行指定的线程的操作。需要提供实现Callable接口的对象
service.submit(new NumberThread());// 适合用于Callable
// 3.需要获取返回结果
Future future = service.submit(new NumberThread());
try {
Object sum = future.get();
System.out.println("总和为:" + sum);
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
// 4.关闭连接池
service.shutdown();
}
}