    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
    015package 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 */
    023public 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}