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Java example source code file (DefaultRedirectHandler.java)

This example source code file (DefaultRedirectHandler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java tags/keywords

defaultredirecthandler, httpcontext, httphost, httprequest, httpresponse, illegalargumentexception, invalid, net, network, protocolexception, redirect_locations, redirectlocations, string, target, uri, urisyntaxexception

The DefaultRedirectHandler.java example source code

/*
 * ====================================================================
 * 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.net.URI;
import java.net.URISyntaxException;

import org.apache.http.annotation.Immutable;

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.client.CircularRedirectException;
import org.apache.http.client.RedirectHandler;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpHead;
import org.apache.http.client.params.ClientPNames;
import org.apache.http.client.utils.URIUtils;
import org.apache.http.params.HttpParams;
import org.apache.http.protocol.HttpContext;
import org.apache.http.protocol.ExecutionContext;

/**
 * Default implementation of {@link RedirectHandler}.
 *
 * @since 4.0
 */
@Immutable
public class DefaultRedirectHandler implements RedirectHandler {

    private final Log log = LogFactory.getLog(getClass());
    
    private static final String REDIRECT_LOCATIONS = "http.protocol.redirect-locations";

    public DefaultRedirectHandler() {
        super();
    }
    
    public boolean isRedirectRequested(
            final HttpResponse response,
            final HttpContext context) {
        if (response == null) {
            throw new IllegalArgumentException("HTTP response may not be null");
        }
        
        int statusCode = response.getStatusLine().getStatusCode();
        switch (statusCode) {
        case HttpStatus.SC_MOVED_TEMPORARILY:
        case HttpStatus.SC_MOVED_PERMANENTLY:
        case HttpStatus.SC_TEMPORARY_REDIRECT:
            HttpRequest request = (HttpRequest) context.getAttribute(
                    ExecutionContext.HTTP_REQUEST);
            String method = request.getRequestLine().getMethod();
            return method.equalsIgnoreCase(HttpGet.METHOD_NAME) 
                || method.equalsIgnoreCase(HttpHead.METHOD_NAME);
        case HttpStatus.SC_SEE_OTHER:
            return true;
        default:
            return false;
        } //end of switch
    }
 
    public URI getLocationURI(
            final HttpResponse response, 
            final HttpContext context) throws ProtocolException {
        if (response == null) {
            throw new IllegalArgumentException("HTTP response 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;
        try {
            uri = new URI(location);            
        } catch (URISyntaxException ex) {
            throw new ProtocolException("Invalid redirect URI: " + location, ex);
        }

        HttpParams params = response.getParams();
        // rfc2616 demands the location value be a complete URI
        // Location       = "Location" ":" absoluteURI
        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");
            }
            
            HttpRequest request = (HttpRequest) context.getAttribute(
                    ExecutionContext.HTTP_REQUEST);
            
            try {
                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);
            }
        }
        
        if (params.isParameterFalse(ClientPNames.ALLOW_CIRCULAR_REDIRECTS)) {
            
            RedirectLocations redirectLocations = (RedirectLocations) context.getAttribute(
                    REDIRECT_LOCATIONS);
            
            if (redirectLocations == null) {
                redirectLocations = new RedirectLocations();
                context.setAttribute(REDIRECT_LOCATIONS, redirectLocations);
            }
            
            URI redirectURI;
            if (uri.getFragment() != null) {
                try {
                    HttpHost target = new HttpHost(
                            uri.getHost(), 
                            uri.getPort(),
                            uri.getScheme());
                    redirectURI = URIUtils.rewriteURI(uri, target, true);
                } catch (URISyntaxException ex) {
                    throw new ProtocolException(ex.getMessage(), ex);
                }
            } else {
                redirectURI = uri;
            }
            
            if (redirectLocations.contains(redirectURI)) {
                throw new CircularRedirectException("Circular redirect to '" +
                        redirectURI + "'");
            } else {
                redirectLocations.add(redirectURI);
            }
        }
        
        return uri;
    }

}

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