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Apache Commons VFS is a Virtual File System library.
There is a newer version: 2.9.0
/*
 * 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.
 */
package org.apache.commons.vfs2.provider.url;

import org.apache.commons.vfs2.FileName;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.provider.AbstractFileNameParser;
import org.apache.commons.vfs2.provider.URLFileName;
import org.apache.commons.vfs2.provider.URLFileNameParser;
import org.apache.commons.vfs2.provider.VfsComponentContext;
import org.apache.commons.vfs2.provider.local.GenericFileNameParser;

/**
 * Implementation for any java.net.url based file system.
 * 
 * Composite of URLFilenameParser and GenericFilenameParser
 */
public class UrlFileNameParser extends AbstractFileNameParser {

    private final URLFileNameParser url = new URLFileNameParser(80);
    private final GenericFileNameParser generic = new GenericFileNameParser();

    public UrlFileNameParser() {
        super();
    }

    @Override
    public boolean encodeCharacter(final char ch) {
        return super.encodeCharacter(ch) || ch == '?';
    }

    /**
     * Parse a URI.
     *
     * @param context The component context.
     * @param base The base FileName.
     * @param uri The target file name.
     * @return The FileName.
     * @throws FileSystemException if an error occurs
     */
    @Override
    public FileName parseUri(final VfsComponentContext context, final FileName base, final String uri)
            throws FileSystemException {
        if (isUrlBased(base, uri)) {
            return url.parseUri(context, base, uri);
        }

        return generic.parseUri(context, base, uri);
    }

    /**
     * Guess if the given file name is an URL with host or not.
     * 

     * VFS treats such URLs differently.
     * 
     * 
     * A file name is URL-based if the base is a {@code URLFileName} or there are only 2 slashes after the scheme. e.g:
     * {@code http://host/path}, {@code file:/path/to/file}, {@code file:///path/to/file}.
     * 
     *
     * @param base The file name is relative to this base.
     * @param fileName The file name.
     * @return true if file name contains two slashes or base was URLFileName.
     */
    protected boolean isUrlBased(final FileName base, final String fileName) {
        if (base instanceof URLFileName) {
            return true;
        }

        return countSlashes(fileName) == 2;
    }

    /**
     * This method counts the slashes after the scheme.
     *
     * @param fileName The file name.
     * @return number of slashes
     */
    protected int countSlashes(final String fileName) {
        int state = 0;
        int nuofSlash = 0;
        for (int pos = 0; pos < fileName.length(); pos++) {
            final char c = fileName.charAt(pos);
            if (state == 0) {
                if (c >= 'a' && c <= 'z') {
                    continue;
                }
                if (c == ':') {
                    state++;
                    continue;
                }
            } else if (state == 1) {
                if (c == '/') {
                    nuofSlash++;
                } else {
                    return nuofSlash;
                }
            }
        }
        return nuofSlash;
    }
}