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Future的使用
get(long timeout, TimeUnit unit)
package java.util.concurrent;
public interface Future<V> {
boolean cancel(boolean mayInterruptIfRunning);
boolean isCancelled();
boolean isDone();
V get() throws InterruptedException, ExecutionException;
V get(long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException;
}
这个接口是在异步线程中执行计算，然后在主线程当中能拿到异步线程计算的结果，如果异步线程中没有执行完，主线程会阻塞住，等异步线程完了之后拿到结果。这个地方有两个方法，get（）和get(long timeout, TimeUnit unit)，后面那个表示在时间范围内执行未完成就抛出异常。
import java.util.concurrent.;
public class TestFuture {
static ExecutorService executorService = Executors.newSingleThreadExecutor();
public static void main(String[] args) {
try {
Future<Integer> future = caculate(3);
Thread.sleep(10000);
int output = future.get(2000, TimeUnit.MILLISECONDS);
System.out.println(output);
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
}
}
public static Future<Integer> caculate (final Integer input){
return executorService.submit(new Callable<Integer>() {
@Override
public Integer call() throws Exception {
Thread.sleep(3000);
return inputinput;
}
});
}
}
