Callable与Runnable的区别:
1.Callable可以返回结果
2.Callable可以抛出异常
Callable一般配合Future与FutureTask使用:
public static void main(String[] args) {
ExecutorService fixedThreadPool = Executors.newFixedThreadPool(3);
// threadA
Future<String> futureA = fixedThreadPool.submit(() -> "A " + Thread.currentThread().getName());
// threadB
Future<String> futureB = fixedThreadPool.submit(() -> {
Thread.sleep(1000);
return "B " + Thread.currentThread().getName();
});
// threadC
Future<String> futureC = fixedThreadPool.submit(() -> {
Thread.sleep(5000);
return "C " + Thread.currentThread().getName();
});
try {
System.out.println(futureA.get());
System.out.println(futureB.get());
System.out.println(futureC.get(1000, TimeUnit.MILLISECONDS));
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
}
}
执行结果:
A pool-1-thread-1
B pool-1-thread-2
java.util.concurrent.TimeoutException
at java.util.concurrent.FutureTask.get(FutureTask.java:205)
at com.pajk.apate.biz.UserBiz.main(UserBiz.java:145)
Future.java
/**
* Waits if necessary for the computation to complete, and then
* retrieves its result.
*/
// 等待直到返回结果
V get() throws InterruptedException, ExecutionException;
/**
* Waits if necessary for at most the given time for the computation
* to complete, and then retrieves its result, if available.
*/
// 最多等待设置的时间,超时抛出TimeoutException
V get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException;