| /* |
| * Copyright 2001-2004 The Apache Software Foundation. |
| * |
| * Licensed 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.codec.net; |
| |
| import java.io.UnsupportedEncodingException; |
| |
| import org.apache.commons.codec.DecoderException; |
| import org.apache.commons.codec.EncoderException; |
| |
| /** |
| * <p> |
| * Implements methods common to all codecs defined in RFC 1522. |
| * </p> |
| * |
| * <p> |
| * <a href="http://www.ietf.org/rfc/rfc1522.txt">RFC 1522</a> |
| * describes techniques to allow the encoding of non-ASCII text in |
| * various portions of a RFC 822 [2] message header, in a manner which |
| * is unlikely to confuse existing message handling software. |
| * </p> |
| |
| * @see <a href="http://www.ietf.org/rfc/rfc1522.txt"> |
| * MIME (Multipurpose Internet Mail Extensions) Part Two: |
| * Message Header Extensions for Non-ASCII Text</a> |
| * </p> |
| * |
| * @author Apache Software Foundation |
| * @since 1.3 |
| * @version $Id: RFC1522Codec.java,v 1.2 2004/04/09 22:21:43 ggregory Exp $ |
| */ |
| abstract class RFC1522Codec { |
| |
| /** |
| * Applies an RFC 1522 compliant encoding scheme to the given string of text with the |
| * given charset. This method constructs the "encoded-word" header common to all the |
| * RFC 1522 codecs and then invokes {@link #doEncoding(byte [])} method of a concrete |
| * class to perform the specific enconding. |
| * |
| * @param text a string to encode |
| * @param charset a charset to be used |
| * |
| * @return RFC 1522 compliant "encoded-word" |
| * |
| * @throws EncoderException thrown if there is an error conidition during the Encoding |
| * process. |
| * @throws UnsupportedEncodingException thrown if charset is not supported |
| * |
| * @see <a href="http://java.sun.com/j2se/1.3/docs/api/java/lang/package-summary.html#charenc">JRE character |
| * encoding names</a> |
| */ |
| protected String encodeText(final String text, final String charset) |
| throws EncoderException, UnsupportedEncodingException |
| { |
| if (text == null) { |
| return null; |
| } |
| StringBuffer buffer = new StringBuffer(); |
| buffer.append("=?"); |
| buffer.append(charset); |
| buffer.append('?'); |
| buffer.append(getEncoding()); |
| buffer.append('?'); |
| byte [] rawdata = doEncoding(text.getBytes(charset)); |
| buffer.append(new String(rawdata, StringEncodings.US_ASCII)); |
| buffer.append("?="); |
| return buffer.toString(); |
| } |
| |
| /** |
| * Applies an RFC 1522 compliant decoding scheme to the given string of text. This method |
| * processes the "encoded-word" header common to all the RFC 1522 codecs and then invokes |
| * {@link #doEncoding(byte [])} method of a concrete class to perform the specific deconding. |
| * |
| * @param text a string to decode |
| * |
| * @throws DecoderException thrown if there is an error conidition during the Decoding |
| * process. |
| * @throws UnsupportedEncodingException thrown if charset specified in the "encoded-word" |
| * header is not supported |
| */ |
| protected String decodeText(final String text) |
| throws DecoderException, UnsupportedEncodingException |
| { |
| if (text == null) { |
| return null; |
| } |
| if ((!text.startsWith("=?")) || (!text.endsWith("?="))) { |
| throw new DecoderException("RFC 1522 violation: malformed encoded content"); |
| } |
| int termnator = text.length() - 2; |
| int from = 2; |
| int to = text.indexOf("?", from); |
| if ((to == -1) || (to == termnator)) { |
| throw new DecoderException("RFC 1522 violation: charset token not found"); |
| } |
| String charset = text.substring(from, to); |
| if (charset.equals("")) { |
| throw new DecoderException("RFC 1522 violation: charset not specified"); |
| } |
| from = to + 1; |
| to = text.indexOf("?", from); |
| if ((to == -1) || (to == termnator)) { |
| throw new DecoderException("RFC 1522 violation: encoding token not found"); |
| } |
| String encoding = text.substring(from, to); |
| if (!getEncoding().equalsIgnoreCase(encoding)) { |
| throw new DecoderException("This codec cannot decode " + |
| encoding + " encoded content"); |
| } |
| from = to + 1; |
| to = text.indexOf("?", from); |
| byte[] data = text.substring(from, to).getBytes(StringEncodings.US_ASCII); |
| data = doDecoding(data); |
| return new String(data, charset); |
| } |
| |
| /** |
| * Returns the codec name (referred to as encoding in the RFC 1522) |
| * |
| * @return name of the codec |
| */ |
| protected abstract String getEncoding(); |
| |
| /** |
| * Encodes an array of bytes using the defined encoding scheme |
| * |
| * @param bytes Data to be encoded |
| * |
| * @return A byte array containing the encoded data |
| * |
| * @throws EncoderException thrown if the Encoder encounters a failure condition |
| * during the encoding process. |
| */ |
| protected abstract byte[] doEncoding(byte[] bytes) throws EncoderException; |
| |
| /** |
| * Decodes an array of bytes using the defined encoding scheme |
| * |
| * @param bytes Data to be decoded |
| * |
| * @return a byte array that contains decoded data |
| * |
| * @throws DecoderException A decoder exception is thrown if a Decoder encounters a |
| * failure condition during the decode process. |
| */ |
| protected abstract byte[] doDecoding(byte[] bytes) throws DecoderException; |
| } |