Java tutorial
/* Copyright 2014 Rick Warren * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ package crud.http.util; import javax.ws.rs.core.Response; import com.google.common.collect.ContiguousSet; import com.google.common.collect.DiscreteDomain; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Range; import com.sun.jersey.api.client.ClientResponse; import com.sun.jersey.api.client.UniformInterfaceException; import crud.fluent.FluentReadableResource; import crud.fluent.FluentReadableResourceProvider; import rx.Observable; import rx.Observer; import rx.Subscriber; /** * Allows an {@link Observer} to treat {@link ClientResponse}s that represent * errors intuitively, as errors, via {@link Observer#onError(Throwable)}, * rather than as expected values, via {@link Observer#onNext(Object)}. * The application provides a set of statuses that it wishes to treat as * errors, and this class will wrap responses with those statuses into * {@link UniformInterfaceException} and dispatch them to {@code onError}. * * If retries are desired, it's recommended to pass an instance of this class * to {@code lift} before calling {@code retry}. Otherwise, the only errors * that will be detected and retried are those that result in exceptions from * Jersey. * * @see UniformInterfaceException#getResponse() * @see FluentReadableResource#lift(rx.Observable.Operator) * @see FluentReadableResourceProvider#lift(rx.Observable.Operator) * @see FluentReadableResource#retry(int) * @see FluentReadableResourceProvider#retry(int) */ public final class FailedResponseOperator implements Observable.Operator<ClientResponse, ClientResponse> { private static final int MIN_STATUS_CODE = 100; private static final int MAX_STATUS_CODE = 599; private static final int MIN_SUCCESS_STATUS_CODE = 200; private static final int MAX_SUCCESS_STATUS_CODE = 299; private static final int MIN_SERVER_ERROR_STATUS_CODE = 500; private static final int MAX_SERVER_ERROR_STATUS_CODE = 599; private static FailedResponseOperator serverErrors = null; private static FailedResponseOperator nonSuccessResponses = null; private final ImmutableSet<Integer> failedStatuses; /** * Treat all 500-range responses as errors. */ public static FailedResponseOperator serverErrors() { if (serverErrors == null) { // Don't delegate to fromStatusCodes(): it does extraneous checking serverErrors = new FailedResponseOperator( ContiguousSet.create(Range.closed(MIN_SERVER_ERROR_STATUS_CODE, MAX_SERVER_ERROR_STATUS_CODE), DiscreteDomain.integers())); } return serverErrors; } /** * Treat all non-200-range responses as errors. */ public static FailedResponseOperator nonSuccessResponses() { if (nonSuccessResponses == null) { final ImmutableSet<Integer> prefix = ContiguousSet .create(Range.closedOpen(MIN_STATUS_CODE, MIN_SUCCESS_STATUS_CODE), DiscreteDomain.integers()); final ImmutableSet<Integer> suffix = ContiguousSet .create(Range.openClosed(MAX_SUCCESS_STATUS_CODE, MAX_STATUS_CODE), DiscreteDomain.integers()); final ImmutableSet<Integer> all = ImmutableSet.<Integer>builder().addAll(prefix).addAll(suffix).build(); // Don't delegate to fromStatusCodes(): it does extraneous checking nonSuccessResponses = new FailedResponseOperator(all); } return nonSuccessResponses; } public static FailedResponseOperator fromClientResponseStatuses( final Iterable<ClientResponse.Status> statuses) { final ImmutableSet.Builder<Integer> statusCodes = new ImmutableSet.Builder<>(); for (final ClientResponse.Status status : statuses) { statusCodes.add(status.getStatusCode()); } // Don't delegate to fromStatusCodes(): it does extraneous checking return new FailedResponseOperator(statusCodes.build()); } public static FailedResponseOperator fromResponseStatuses(final Iterable<Response.Status> statuses) { final ImmutableSet.Builder<Integer> statusCodes = new ImmutableSet.Builder<>(); for (final Response.Status status : statuses) { statusCodes.add(status.getStatusCode()); } // Don't delegate to fromStatusCodes(): it does extraneous checking return new FailedResponseOperator(statusCodes.build()); } public static FailedResponseOperator fromStatusCodes(final Iterable<Integer> statuses) { for (final Integer status : statuses) { if (status < MIN_STATUS_CODE || status > MAX_STATUS_CODE) { throw new IllegalArgumentException("HTTP status code out of range: " + status); } } return new FailedResponseOperator(statuses); } private FailedResponseOperator(final Iterable<Integer> failedStatuses) { this.failedStatuses = ImmutableSet.copyOf(failedStatuses); } @Override public Subscriber<? super ClientResponse> call(final Subscriber<? super ClientResponse> sub) { return new ErrorResponseSubscriber(sub); } private final class ErrorResponseSubscriber extends Subscriber<ClientResponse> { private final Subscriber<? super ClientResponse> delegate; private volatile boolean errorOccurred = false; public ErrorResponseSubscriber(final Subscriber<? super ClientResponse> delegate) { super(delegate); this.delegate = delegate; } @Override public void onNext(final ClientResponse response) { if (this.errorOccurred) { return; } if (FailedResponseOperator.this.failedStatuses.contains(response.getStatus())) { this.errorOccurred = true; this.delegate.onError(new UniformInterfaceException(response)); } else { this.delegate.onNext(response); } } @Override public void onCompleted() { if (this.errorOccurred) { return; } this.delegate.onCompleted(); } @Override public void onError(final Throwable e) { if (this.errorOccurred) { return; } this.delegate.onError(e); } } }