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Java example source code file (URIUtils.java)

This example source code file (URIUtils.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

base, httphost, illegalargumentexception, immutable, net, network, reference, stack, string, stringbuilder, uri, urisyntaxexception, uriutils, util

The URIUtils.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.client.utils;

import java.net.URI;
import java.net.URISyntaxException;
import java.util.Stack;

import org.apache.http.annotation.Immutable;

import org.apache.http.HttpHost;

/**
 * A collection of utilities for {@link URI URIs}, to workaround
 * bugs within the class or for ease-of-use features.
 *
 * @since 4.0
 */
@Immutable
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.
         * 
         * @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 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());
    }

    /**
     * A convenience method for creating a new {@link URI} whose scheme, host
     * and port are taken from the target host, but whose path, query and
     * fragment are taken from the existing URI. The fragment is only used if
     * dropFragment is false.
     * 
     * @param uri
     *            Contains the path, query and fragment to use.
     * @param target
     *            Contains the scheme, host and port to use.
     * @param dropFragment
     *            True if the fragment should not be copied.
     * 
     * @throws URISyntaxException
     *             If the resulting URI is invalid.
     */
    public static URI rewriteURI(
            final URI uri, 
            final HttpHost target,
            boolean dropFragment) throws URISyntaxException {
        if (uri == null) {
            throw new IllegalArgumentException("URI may nor be null");
        }
        if (target != null) {
            return URIUtils.createURI(
                    target.getSchemeName(), 
                    target.getHostName(), 
                    target.getPort(), 
                    uri.getRawPath(), 
                    uri.getRawQuery(), 
                    dropFragment ? null : uri.getRawFragment());
        } else {
            return URIUtils.createURI(
                    null, 
                    null, 
                    -1, 
                    uri.getRawPath(), 
                    uri.getRawQuery(), 
                    dropFragment ? null : uri.getRawFragment());
        }
    }
    
    /**
     * A convenience method for
     * {@link URIUtils#rewriteURI(URI, HttpHost, boolean)} that always keeps the
     * fragment.
     */
    public static URI rewriteURI(
            final URI uri, 
            final HttpHost target) throws URISyntaxException {
        return rewriteURI(uri, target, false);
    }
    
    /**
     * 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 bugs in
     * java.net.URI (e.g. <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");
        }
        String s = reference.toString();
        if (s.startsWith("?")) {
            return resolveReferenceStartingWithQueryString(baseURI, reference);
        }
        boolean emptyReference = s.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 removeDotSegments(resolved);
    }

    /**
     * Resolves a reference starting with a query string.
     * 
     * @param baseURI the base URI
     * @param reference the URI reference starting with a query string
     * @return the resulting URI
     */
    private static URI resolveReferenceStartingWithQueryString(
            final URI baseURI, final URI reference) {
        String baseUri = baseURI.toString();
        baseUri = baseUri.indexOf('?') > -1 ?
            baseUri.substring(0, baseUri.indexOf('?')) : baseUri;
        return URI.create(baseUri + reference.toString());
    }

    /**
     * Removes dot segments according to RFC 3986, section 5.2.4
     * 
     * @param uri the original URI
     * @return the URI without dot segments
     */
    private static URI removeDotSegments(URI uri) {
        String path = uri.getPath();
        if ((path == null) || (path.indexOf("/.") == -1)) {
            // No dot segments to remove
            return uri;
        }
        String[] inputSegments = path.split("/");
        Stack<String> outputSegments = new Stack();
        for (int i = 0; i < inputSegments.length; i++) {
            if ((inputSegments[i].length() == 0)
                || (".".equals(inputSegments[i]))) {
                // Do nothing
            } else if ("..".equals(inputSegments[i])) {
                if (!outputSegments.isEmpty()) {
                    outputSegments.pop();
                }
            } else {
                outputSegments.push(inputSegments[i]);
            }
        }
        StringBuilder outputBuffer = new StringBuilder();
        for (String outputSegment : outputSegments) {
            outputBuffer.append('/').append(outputSegment);
        }
        try {
            return new URI(uri.getScheme(), uri.getAuthority(),
                outputBuffer.toString(), uri.getQuery(), uri.getFragment());
        } catch (URISyntaxException e) {
            throw new IllegalArgumentException(e);
        }
    }

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

}

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