Java tutorial
package main.amos.util; /* * ==================================================================== * 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/>. * */ import java.net.URI; import java.net.URISyntaxException; import java.net.URLEncoder; import java.util.Locale; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.http.Header; import org.apache.http.HttpHost; import org.apache.http.HttpRequest; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.ProtocolException; import org.apache.http.annotation.Immutable; import org.apache.http.client.CircularRedirectException; import org.apache.http.client.RedirectStrategy; import org.apache.http.client.config.RequestConfig; import org.apache.http.client.methods.*; import org.apache.http.client.protocol.HttpClientContext; import org.apache.http.client.utils.URIBuilder; import org.apache.http.client.utils.URIUtils; import org.apache.http.impl.client.RedirectLocations; import org.apache.http.protocol.HttpContext; import org.apache.http.util.Args; import org.apache.http.util.Asserts; import org.apache.http.util.TextUtils; /** * //?? */ public class SelfRedirectStrategy implements RedirectStrategy { private final Log log = LogFactory.getLog(getClass()); /** * @deprecated (4.3) use {@link org.apache.http.client.protocol.HttpClientContext#REDIRECT_LOCATIONS}. */ @Deprecated public static final String REDIRECT_LOCATIONS = "http.protocol.redirect-locations"; public static final SelfRedirectStrategy INSTANCE = new SelfRedirectStrategy(); /** * Redirectable methods. */ private static final String[] REDIRECT_METHODS = new String[] { HttpGet.METHOD_NAME, HttpHead.METHOD_NAME, HttpPost.METHOD_NAME }; public SelfRedirectStrategy() { super(); } public boolean isRedirected(final HttpRequest request, final HttpResponse response, final HttpContext context) throws ProtocolException { Args.notNull(request, "HTTP request"); Args.notNull(response, "HTTP response"); final int statusCode = response.getStatusLine().getStatusCode(); final String method = request.getRequestLine().getMethod(); final Header locationHeader = response.getFirstHeader("location"); switch (statusCode) { case HttpStatus.SC_MOVED_TEMPORARILY: return isRedirectable(method) && locationHeader != null; case HttpStatus.SC_MOVED_PERMANENTLY: case HttpStatus.SC_TEMPORARY_REDIRECT: return isRedirectable(method); case HttpStatus.SC_SEE_OTHER: return true; default: return false; } //end of switch } public URI getLocationURI(final HttpRequest request, final HttpResponse response, final HttpContext context) throws ProtocolException { Args.notNull(request, "HTTP request"); Args.notNull(response, "HTTP response"); Args.notNull(context, "HTTP context"); final HttpClientContext clientContext = HttpClientContext.adapt(context); //get the location header to find out where to redirect to final Header locationHeader = response.getFirstHeader("location"); if (locationHeader == null) { // got a redirect response, but no location header throw new ProtocolException( "Received redirect response " + response.getStatusLine() + " but no location header"); } final String location = locationHeader.getValue(); if (this.log.isDebugEnabled()) { this.log.debug("Redirect requested to location '" + location + "'"); } final RequestConfig config = clientContext.getRequestConfig(); URI uri = createLocationURI(location.replaceAll(" ", "%20")); // rfc2616 demands the location value be a complete URI // Location = "Location" ":" absoluteURI try { if (!uri.isAbsolute()) { if (!config.isRelativeRedirectsAllowed()) { throw new ProtocolException("Relative redirect location '" + uri + "' not allowed"); } // Adjust location URI final HttpHost target = clientContext.getTargetHost(); Asserts.notNull(target, "Target host"); final URI requestURI = new URI(request.getRequestLine().getUri()); final URI absoluteRequestURI = URIUtils.rewriteURI(requestURI, target, false); uri = URIUtils.resolve(absoluteRequestURI, uri); } } catch (final URISyntaxException ex) { throw new ProtocolException(ex.getMessage(), ex); } RedirectLocations redirectLocations = (RedirectLocations) clientContext .getAttribute(HttpClientContext.REDIRECT_LOCATIONS); if (redirectLocations == null) { redirectLocations = new RedirectLocations(); context.setAttribute(HttpClientContext.REDIRECT_LOCATIONS, redirectLocations); } if (!config.isCircularRedirectsAllowed()) { if (redirectLocations.contains(uri)) { throw new CircularRedirectException("Circular redirect to '" + uri + "'"); } } redirectLocations.add(uri); return uri; } /** * @since 4.1 */ protected URI createLocationURI(final String location) throws ProtocolException { System.out.println("redirect_location:" + location); try { final URIBuilder b = new URIBuilder(new URI(location).normalize()); final String host = b.getHost(); if (host != null) { b.setHost(host.toLowerCase(Locale.ENGLISH)); } final String path = b.getPath(); if (TextUtils.isEmpty(path)) { b.setPath("/"); } return b.build(); } catch (final URISyntaxException ex) { throw new ProtocolException("Invalid redirect URI: " + location, ex); } } /** * @since 4.2 */ protected boolean isRedirectable(final String method) { for (final String m : REDIRECT_METHODS) { if (m.equalsIgnoreCase(method)) { return true; } } return false; } public HttpUriRequest getRedirect(final HttpRequest request, final HttpResponse response, final HttpContext context) throws ProtocolException { final URI uri = getLocationURI(request, response, context); final String method = request.getRequestLine().getMethod(); if (method.equalsIgnoreCase(HttpHead.METHOD_NAME)) { return new HttpHead(uri); } else if (method.equalsIgnoreCase(HttpGet.METHOD_NAME)) { return new HttpGet(uri); } else if (method.equalsIgnoreCase(HttpPost.METHOD_NAME)) { return new HttpPost(uri); } else { final int status = response.getStatusLine().getStatusCode(); if (status == HttpStatus.SC_TEMPORARY_REDIRECT) { return RequestBuilder.copy(request).setUri(uri).build(); } else { return new HttpGet(uri); } } } }