Java tutorial
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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.nutch.protocol.httpclient; import java.net.URI; import java.net.URISyntaxException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.http.Header; import org.apache.http.HttpEntityEnclosingRequest; 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.methods.HttpDelete; import org.apache.http.client.methods.HttpEntityEnclosingRequestBase; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpHead; import org.apache.http.client.methods.HttpOptions; import org.apache.http.client.methods.HttpPatch; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.methods.HttpPut; import org.apache.http.client.methods.HttpTrace; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.client.params.ClientPNames; import org.apache.http.client.utils.URIUtils; import org.apache.http.impl.client.DefaultRedirectStrategy; import org.apache.http.impl.client.LaxRedirectStrategy; import org.apache.http.impl.client.RedirectLocations; import org.apache.http.params.HttpParams; import org.apache.http.protocol.ExecutionContext; import org.apache.http.protocol.HttpContext; /** * Default implementation of {@link RedirectStrategy}. This strategy honors the restrictions * on automatic redirection of entity enclosing methods such as POST and PUT imposed by the * HTTP specification. <tt>302 Moved Temporarily</tt>, <tt>301 Moved Permanently</tt> and * <tt>307 Temporary Redirect</tt> status codes will result in an automatic redirect of * HEAD and GET methods only. POST and PUT methods will not be automatically redirected * as requiring user confirmation. * <p/> * The restriction on automatic redirection of POST methods can be relaxed by using * {@link LaxRedirectStrategy} instead of {@link DefaultRedirectStrategy}. * * @see LaxRedirectStrategy * @since 4.1 */ @Immutable public class HttpClientRedirectStrategy implements RedirectStrategy { private final Log log = LogFactory.getLog(getClass()); public static final String REDIRECT_LOCATIONS = "http.protocol.redirect-locations"; /** * Redirectable methods. */ private static final String[] REDIRECT_METHODS = new String[] { HttpGet.METHOD_NAME, HttpHead.METHOD_NAME }; public HttpClientRedirectStrategy() { super(); } public boolean isRedirected(final HttpRequest request, final HttpResponse response, final HttpContext context) throws ProtocolException { if (request == null) { throw new IllegalArgumentException("HTTP request may not be null"); } if (response == null) { throw new IllegalArgumentException("HTTP response may not be null"); } int statusCode = response.getStatusLine().getStatusCode(); if ((statusCode >= 300 && statusCode < 400 && statusCode != 304) || statusCode == 401) { return false; } String method = request.getRequestLine().getMethod(); 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 { if (request == null) { throw new IllegalArgumentException("HTTP request may not be null"); } if (response == null) { throw new IllegalArgumentException("HTTP response may not be null"); } if (context == null) { throw new IllegalArgumentException("HTTP context may not be null"); } //get the location header to find out where to redirect to 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"); } String location = locationHeader.getValue(); if (this.log.isDebugEnabled()) { this.log.debug("Redirect requested to location '" + location + "'"); } URI uri = createLocationURI(location); HttpParams params = request.getParams(); // rfc2616 demands the location value be a complete URI // Location = "Location" ":" absoluteURI try { // Drop fragment uri = URIUtils.rewriteURI(uri); if (!uri.isAbsolute()) { if (params.isParameterTrue(ClientPNames.REJECT_RELATIVE_REDIRECT)) { throw new ProtocolException("Relative redirect location '" + uri + "' not allowed"); } // Adjust location URI HttpHost target = (HttpHost) context.getAttribute(ExecutionContext.HTTP_TARGET_HOST); if (target == null) { throw new IllegalStateException("Target host not available " + "in the HTTP context"); } URI requestURI = new URI(request.getRequestLine().getUri()); URI absoluteRequestURI = URIUtils.rewriteURI(requestURI, target, true); uri = URIUtils.resolve(absoluteRequestURI, uri); } } catch (URISyntaxException ex) { throw new ProtocolException(ex.getMessage(), ex); } RedirectLocations redirectLocations = (RedirectLocations) context.getAttribute(REDIRECT_LOCATIONS); if (redirectLocations == null) { redirectLocations = new RedirectLocations(); context.setAttribute(REDIRECT_LOCATIONS, redirectLocations); } if (params.isParameterFalse(ClientPNames.ALLOW_CIRCULAR_REDIRECTS)) { 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 { try { return new URI(location).normalize(); } catch (URISyntaxException ex) { throw new ProtocolException("Invalid redirect URI: " + location, ex); } } /** * @since 4.2 */ protected boolean isRedirectable(final String method) { for (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 { URI uri = getLocationURI(request, response, context); 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 { int status = response.getStatusLine().getStatusCode(); if (status == HttpStatus.SC_TEMPORARY_REDIRECT) { if (method.equalsIgnoreCase(HttpPost.METHOD_NAME)) { return copyEntity(new HttpPost(uri), request); } else if (method.equalsIgnoreCase(HttpPut.METHOD_NAME)) { return copyEntity(new HttpPut(uri), request); } else if (method.equalsIgnoreCase(HttpDelete.METHOD_NAME)) { return new HttpDelete(uri); } else if (method.equalsIgnoreCase(HttpTrace.METHOD_NAME)) { return new HttpTrace(uri); } else if (method.equalsIgnoreCase(HttpOptions.METHOD_NAME)) { return new HttpOptions(uri); } else if (method.equalsIgnoreCase(HttpPatch.METHOD_NAME)) { return copyEntity(new HttpPatch(uri), request); } } return new HttpGet(uri); } } private HttpUriRequest copyEntity(final HttpEntityEnclosingRequestBase redirect, final HttpRequest original) { if (original instanceof HttpEntityEnclosingRequest) { redirect.setEntity(((HttpEntityEnclosingRequest) original).getEntity()); } return redirect; } }