Create and resolve URI : URI « Network « Java Tutorial

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/*
 * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/client/utils/URIUtils.java $
 * $Revision: 687159 $
 * $Date: 2008-08-19 22:20:46 +0100 (Tue, 19 Aug 2008) $
 *
 *
 *  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;


/**
 * A collection of utilities for {@link URI URIs}, to workaround
 * bugs within the class or for ease-of-use features.
 */
public class URIUtils {

     /**
         * Constructs a {@link URI} using all the parameters. This should be
         * used instead of
         * {@link URI#URI(String, String, String, int, String, String, String)}
         * or any of the other URI multi-argument URI constructors.
         * 
         * See <a
         * href="https://issues.apache.org/jira/browse/HTTPCLIENT-730">HTTPCLIENT-730</a>
         * for more information.
         * 
         * @param scheme
         *            Scheme name
         * @param host
         *            Host name
         * @param port
         *            Port number
         * @param path
         *            Path
         * @param query
         *            Query
         * @param fragment
         *            Fragment
         * 
         * @throws URISyntaxException
         *             If both a scheme and a path are given but the path is
         *             relative, if the URI string constructed from the given
         *             components violates RFC&nbsp;2396, or if the authority
         *             component of the string is present but cannot be parsed
         *             as a server-based authority
         */
    public static URI createURI(
            final String scheme,
            final String host,
            int port,
            final String path,
            final String query,
            final String fragment) throws URISyntaxException {
        
        StringBuilder buffer = new StringBuilder();
        if (host != null) {
            if (scheme != null) {
                buffer.append(scheme);
                buffer.append("://");
            }
            buffer.append(host);
            if (port > 0) {
                buffer.append(':');
                buffer.append(port);
            }
        }
        if (path == null || !path.startsWith("/")) {
            buffer.append('/');
        }
        if (path != null) {
            buffer.append(path);
        }
        if (query != null) {
            buffer.append('?');
            buffer.append(query);
        }
        if (fragment != null) {
            buffer.append('#');
            buffer.append(fragment);
        }
        return new URI(buffer.toString());
    }

    /**
     * Resolves a URI reference against a base URI. Work-around for bug in
     * java.net.URI (<http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4708535>)
     *
     * @param baseURI the base URI
     * @param reference the URI reference
     * @return the resulting URI
     */
    public static URI resolve(final URI baseURI, final String reference) {
        return URIUtils.resolve(baseURI, URI.create(reference));
    }

    /**
     * Resolves a URI reference against a base URI. Work-around for bug in
     * java.net.URI (<http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4708535>)
     *
     * @param baseURI the base URI
     * @param reference the URI reference
     * @return the resulting URI
     */
    public static URI resolve(final URI baseURI, URI reference){
        if (baseURI == null) {
            throw new IllegalArgumentException("Base URI may nor be null");
        }
        if (reference == null) {
            throw new IllegalArgumentException("Reference URI may nor be null");
        }
        boolean emptyReference = reference.toString().length() == 0;
        if (emptyReference) {
            reference = URI.create("#");
        }
        URI resolved = baseURI.resolve(reference);
        if (emptyReference) {
            String resolvedString = resolved.toString();
            resolved = URI.create(resolvedString.substring(0,
                resolvedString.indexOf('#')));
        }
        return resolved;
    }

    /**
     * This class should not be instantiated.
     */
    private URIUtils() {
    }

}