Code
Future 接口 的局限性有很多，其中一个就是需要主动的去询问是否完成，如果等子线程的任务完成以后，通知我，那岂不是更好？
public class FutureInAction3 { public static void main(String[] args) { Future<String> future = invoke(() -> { try { Thread.sleep(10000L); return "I am Finished."; } catch (InterruptedException e) { return "I am Error"; } }); future.setCompletable(new Completable<String>() { @Override public void complete(String s) { System.out.println("complete called ---- " + s); } @Override public void exception(Throwable cause) { System.out.println("error"); cause.printStackTrace(); } }); System.out.println("....do something else ....."); System.out.println("try to get result ->" + future.get()); } private static <T> Future<T> invoke(Callable<T> callable) { AtomicReference<T> result = new AtomicReference<>(); AtomicBoolean finished = new AtomicBoolean(false); Future<T> future = new Future<T>() { private Completable<T> completable; @Override public T get() { return result.get(); } @Override public boolean isDone() { return finished.get(); } // 设置完成 @Override public void setCompletable(Completable<T> completable) { this.completable = completable; } // 获取 @Override public Completable<T> getCompletable() { return completable; } }; Thread t = new Thread(() -> { try { T value = callable.action(); result.set(value); finished.set(true); if (future.getCompletable() != null) future.getCompletable().complete(value); } catch (Throwable cause) { if (future.getCompletable() != null) future.getCompletable().exception(cause); } }); t.start(); return future; } private interface Future<T> { T get(); boolean isDone(); // 1 void setCompletable(Completable<T> completable); // 2 Completable<T> getCompletable(); } private interface Callable<T> { T action(); } // 回调接口 private interface Completable<T> { void complete(T t); void exception(Throwable cause); } }
