Java tutorial
/* * ==================================================================== * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * */ package org.apache.http.impl.client; import java.io.IOException; import java.io.InterruptedIOException; import java.net.ConnectException; import java.net.UnknownHostException; import java.util.Arrays; import java.util.Collection; import java.util.HashSet; import java.util.Set; import javax.net.ssl.SSLException; import org.apache.http.HttpEntityEnclosingRequest; import org.apache.http.HttpRequest; import org.apache.http.annotation.Immutable; import org.apache.http.client.HttpRequestRetryHandler; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.client.protocol.HttpClientContext; import org.apache.http.protocol.HttpContext; import org.apache.http.util.Args; /** * The default {@link HttpRequestRetryHandler} used by request executors. * * @since 4.0 */ @Immutable public class DefaultHttpRequestRetryHandler implements HttpRequestRetryHandler { public static final DefaultHttpRequestRetryHandler INSTANCE = new DefaultHttpRequestRetryHandler(); /** the number of times a method will be retried */ private final int retryCount; /** Whether or not methods that have successfully sent their request will be retried */ private final boolean requestSentRetryEnabled; private final Set<Class<? extends IOException>> nonRetriableClasses; /** * Create the request retry handler using the specified IOException classes * * @param retryCount how many times to retry; 0 means no retries * @param requestSentRetryEnabled true if it's OK to retry requests that have been sent * @param clazzes the IOException types that should not be retried * @since 4.3 */ protected DefaultHttpRequestRetryHandler(final int retryCount, final boolean requestSentRetryEnabled, final Collection<Class<? extends IOException>> clazzes) { super(); this.retryCount = retryCount; this.requestSentRetryEnabled = requestSentRetryEnabled; this.nonRetriableClasses = new HashSet<Class<? extends IOException>>(); for (final Class<? extends IOException> clazz : clazzes) { this.nonRetriableClasses.add(clazz); } } /** * Create the request retry handler using the following list of * non-retriable IOException classes: <br> * <ul> * <li>InterruptedIOException</li> * <li>UnknownHostException</li> * <li>ConnectException</li> * <li>SSLException</li> * </ul> * @param retryCount how many times to retry; 0 means no retries * @param requestSentRetryEnabled true if it's OK to retry requests that have been sent */ @SuppressWarnings("unchecked") public DefaultHttpRequestRetryHandler(final int retryCount, final boolean requestSentRetryEnabled) { this(retryCount, requestSentRetryEnabled, Arrays.asList(InterruptedIOException.class, UnknownHostException.class, ConnectException.class, SSLException.class)); } /** * Create the request retry handler with a retry count of 3, requestSentRetryEnabled false * and using the following list of non-retriable IOException classes: <br> * <ul> * <li>InterruptedIOException</li> * <li>UnknownHostException</li> * <li>ConnectException</li> * <li>SSLException</li> * </ul> */ public DefaultHttpRequestRetryHandler() { this(3, false); } /** * Used <code>retryCount</code> and <code>requestSentRetryEnabled</code> to determine * if the given method should be retried. */ public boolean retryRequest(final IOException exception, final int executionCount, final HttpContext context) { Args.notNull(exception, "Exception parameter"); Args.notNull(context, "HTTP context"); if (executionCount > this.retryCount) { // Do not retry if over max retry count return false; } if (this.nonRetriableClasses.contains(exception.getClass())) { return false; } else { for (final Class<? extends IOException> rejectException : this.nonRetriableClasses) { if (rejectException.isInstance(exception)) { return false; } } } final HttpClientContext clientContext = HttpClientContext.adapt(context); final HttpRequest request = clientContext.getRequest(); if (requestIsAborted(request)) { return false; } if (handleAsIdempotent(request)) { // Retry if the request is considered idempotent return true; } if (!clientContext.isRequestSent() || this.requestSentRetryEnabled) { // Retry if the request has not been sent fully or // if it's OK to retry methods that have been sent return true; } // otherwise do not retry return false; } /** * @return <code>true</code> if this handler will retry methods that have * successfully sent their request, <code>false</code> otherwise */ public boolean isRequestSentRetryEnabled() { return requestSentRetryEnabled; } /** * @return the maximum number of times a method will be retried */ public int getRetryCount() { return retryCount; } /** * @since 4.2 */ protected boolean handleAsIdempotent(final HttpRequest request) { return !(request instanceof HttpEntityEnclosingRequest); } /** * @since 4.2 * * @deprecated (4.3) */ @Deprecated protected boolean requestIsAborted(final HttpRequest request) { HttpRequest req = request; if (request instanceof RequestWrapper) { // does not forward request to original req = ((RequestWrapper) request).getOriginal(); } return (req instanceof HttpUriRequest && ((HttpUriRequest) req).isAborted()); } }