    001    //  Copyright 2008 The Apache Software Foundation
    002    //
    003    // Licensed under the Apache License, Version 2.0 (the "License");
    004    // you may not use this file except in compliance with the License.
    005    // You may obtain a copy of the License at
    006    //
    007    //     http://www.apache.org/licenses/LICENSE-2.0
    008    //
    009    // Unless required by applicable law or agreed to in writing, software
    010    // distributed under the License is distributed on an "AS IS" BASIS,
    011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    012    // See the License for the specific language governing permissions and
    013    // limitations under the License.
    014
    015    package org.apache.tapestry5.services;
    016
    017    /**
    018     * Service used to encode or decode strings that are placed into URLs.  This is used as an alternative to UUEncoding.
    019     * Alphabetics, numbers and some punctuation ("-", "_", ".", ":") are passed through as is, the "$" character is an
    020     * escape, followed by either another "$", or by a four digit hex unicode number.  A null input (not a blank input, but
    021     * actual null) has a special encoding, "$N". Likewise, the blank string has the special encoding "$B".
    022     */
    023    public interface URLEncoder
    024    {
    025        /**
    026         * Given an input value containing any characters, returns the input string, or an encoded version of the string (as
    027         * outlined above).
    028         *
    029         * @param input string to be encoded, which may be null
    030         * @return encoded version of input
    031         */
    032        String encode(String input);
    033
    034        /**
    035         * Given a previously encoded string, returns the original input.
    036         *
    037         * @param input encoded string (may not be null)
    038         * @return decoded input
    039         */
    040        String decode(String input);
    041    }