总结11

包装catch错误

/**
 * A {@link NameResolver} that resolves an {@link InetSocketAddress} using JDK's built-in domain name lookup mechanism.
 * Note that this resolver performs a blocking name lookup from the caller thread.
 */
public class DefaultNameResolver extends SimpleNameResolver<InetSocketAddress> {

    public DefaultNameResolver(EventExecutor executor) {
        super(executor);
    }

    @Override
    protected boolean doIsResolved(InetSocketAddress address) {
        return !address.isUnresolved();
    }

    @Override
    protected void doResolve(InetSocketAddress unresolvedAddress, Promise<InetSocketAddress> promise) throws Exception {
        try {
            promise.setSuccess(
                    new InetSocketAddress(
                            InetAddress.getByName(unresolvedAddress.getHostString()),
                            unresolvedAddress.getPort()));
        } catch (UnknownHostException e) {
            promise.setFailure(e);
        }
    }
}

扩展泛型接口

/**
 * The result of an asynchronous operation.
 */
@SuppressWarnings("ClassNameSameAsAncestorName")
public interface Future<V> extends java.util.concurrent.Future<V> {

    /**
     * Returns {@code true} if and only if the I/O operation was completed
     * successfully.
     */
    boolean isSuccess();

    /**
     * returns {@code true} if and only if the operation can be cancelled via {@link #cancel(boolean)}.
     */
    boolean isCancellable();

    /**
     * Returns the cause of the failed I/O operation if the I/O operation has
     * failed.
     *
     * @return the cause of the failure.
     *         {@code null} if succeeded or this future is not
     *         completed yet.
     */
    Throwable cause();

    /**
     * Adds the specified listener to this future.  The
     * specified listener is notified when this future is
     * {@linkplain #isDone() done}.  If this future is already
     * completed, the specified listener is notified immediately.
     */
    Future<V> addListener(GenericFutureListener<? extends Future<? super V>> listener);

    /**
     * Adds the specified listeners to this future.  The
     * specified listeners are notified when this future is
     * {@linkplain #isDone() done}.  If this future is already
     * completed, the specified listeners are notified immediately.
     */
    Future<V> addListeners(GenericFutureListener<? extends Future<? super V>>... listeners);

    /**
     * Removes the specified listener from this future.
     * The specified listener is no longer notified when this
     * future is {@linkplain #isDone() done}.  If the specified
     * listener is not associated with this future, this method
     * does nothing and returns silently.
     */
    Future<V> removeListener(GenericFutureListener<? extends Future<? super V>> listener);

    /**
     * Removes the specified listeners from this future.
     * The specified listeners are no longer notified when this
     * future is {@linkplain #isDone() done}.  If the specified
     * listeners are not associated with this future, this method
     * does nothing and returns silently.
     */
    Future<V> removeListeners(GenericFutureListener<? extends Future<? super V>>... listeners);

    /**
     * Waits for this future until it is done, and rethrows the cause of the failure if this future
     * failed.
     */
    Future<V> sync() throws InterruptedException;

    /**
     * Waits for this future until it is done, and rethrows the cause of the failure if this future
     * failed.
     */
    Future<V> syncUninterruptibly();

    /**
     * Waits for this future to be completed.
     *
     * @throws InterruptedException
     *         if the current thread was interrupted
     */
    Future<V> await() throws InterruptedException;

    /**
     * Waits for this future to be completed without
     * interruption.  This method catches an {@link InterruptedException} and
     * discards it silently.
     */
    Future<V> awaitUninterruptibly();

    /**
     * Waits for this future to be completed within the
     * specified time limit.
     *
     * @return {@code true} if and only if the future was completed within
     *         the specified time limit
     *
     * @throws InterruptedException
     *         if the current thread was interrupted
     */
    boolean await(long timeout, TimeUnit unit) throws InterruptedException;

    /**
     * Waits for this future to be completed within the
     * specified time limit.
     *
     * @return {@code true} if and only if the future was completed within
     *         the specified time limit
     *
     * @throws InterruptedException
     *         if the current thread was interrupted
     */
    boolean await(long timeoutMillis) throws InterruptedException;

    /**
     * Waits for this future to be completed within the
     * specified time limit without interruption.  This method catches an
     * {@link InterruptedException} and discards it silently.
     *
     * @return {@code true} if and only if the future was completed within
     *         the specified time limit
     */
    boolean awaitUninterruptibly(long timeout, TimeUnit unit);

    /**
     * Waits for this future to be completed within the
     * specified time limit without interruption.  This method catches an
     * {@link InterruptedException} and discards it silently.
     *
     * @return {@code true} if and only if the future was completed within
     *         the specified time limit
     */
    boolean awaitUninterruptibly(long timeoutMillis);

    /**
     * Return the result without blocking. If the future is not done yet this will return {@code null}.
     *
     * As it is possible that a {@code null} value is used to mark the future as successful you also need to check
     * if the future is really done with {@link #isDone()} and not relay on the returned {@code null} value.
     */
    V getNow();

    /**
     * {@inheritDoc}
     *
     * If the cancellation was successful it will fail the future with an {@link CancellationException}.
     */
    @Override
    boolean cancel(boolean mayInterruptIfRunning);
}