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}