| /* |
| * 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.codec.net; |
| |
| import java.io.UnsupportedEncodingException; |
| import java.nio.charset.Charset; |
| |
| import org.apache.commons.codec.DecoderException; |
| import org.apache.commons.codec.EncoderException; |
| import org.apache.commons.codec.binary.StringUtils; |
| |
| /** |
| * Implements methods common to all codecs defined in RFC 1522. |
| * <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> |
| * <p> |
| * This class is immutable and thread-safe. |
| * </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> |
| * |
| * @since 1.3 |
| */ |
| abstract class RFC1522Codec { |
| |
| /** Separator. */ |
| protected static final char SEP = '?'; |
| |
| /** Prefix. */ |
| protected static final String POSTFIX = "?="; |
| |
| /** Postfix. */ |
| protected static final String PREFIX = "=?"; |
| |
| /** |
| * Applies an RFC 1522 compliant encoding scheme to the given string of text with the given charset. |
| * <p> |
| * 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 encoding. |
| * |
| * @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 condition during the Encoding process. |
| * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a> |
| */ |
| protected String encodeText(final String text, final Charset charset) throws EncoderException { |
| if (text == null) { |
| return null; |
| } |
| final StringBuilder buffer = new StringBuilder(); |
| buffer.append(PREFIX); |
| buffer.append(charset); |
| buffer.append(SEP); |
| buffer.append(this.getEncoding()); |
| buffer.append(SEP); |
| buffer.append(StringUtils.newStringUsAscii(this.doEncoding(text.getBytes(charset)))); |
| buffer.append(POSTFIX); |
| return buffer.toString(); |
| } |
| |
| /** |
| * Applies an RFC 1522 compliant encoding scheme to the given string of text with the given charset. |
| * <p> |
| * 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 encoding. |
| * |
| * @param text |
| * a string to encode |
| * @param charsetName |
| * the charset to use |
| * @return RFC 1522 compliant "encoded-word" |
| * @throws EncoderException |
| * thrown if there is an error condition during the Encoding process. |
| * @throws UnsupportedEncodingException |
| * if charset is not available |
| * |
| * @see <a href="http://download.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html">Standard charsets</a> |
| */ |
| protected String encodeText(final String text, final String charsetName) |
| throws EncoderException, UnsupportedEncodingException { |
| if (text == null) { |
| return null; |
| } |
| return this.encodeText(text, Charset.forName(charsetName)); |
| } |
| |
| /** |
| * Applies an RFC 1522 compliant decoding scheme to the given string of text. |
| * <p> |
| * This method processes the "encoded-word" header common to all the RFC 1522 codecs and then invokes |
| * {@link #doDecoding(byte[])} method of a concrete class to perform the specific decoding. |
| * |
| * @param text |
| * a string to decode |
| * @return A new decoded String or {@code null} if the input is {@code null}. |
| * @throws DecoderException |
| * thrown if there is an error condition 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(PREFIX) || !text.endsWith(POSTFIX)) { |
| throw new DecoderException("RFC 1522 violation: malformed encoded content"); |
| } |
| final int terminator = text.length() - 2; |
| int from = 2; |
| int to = text.indexOf(SEP, from); |
| if (to == terminator) { |
| throw new DecoderException("RFC 1522 violation: charset token not found"); |
| } |
| final String charset = text.substring(from, to); |
| if (charset.equals("")) { |
| throw new DecoderException("RFC 1522 violation: charset not specified"); |
| } |
| from = to + 1; |
| to = text.indexOf(SEP, from); |
| if (to == terminator) { |
| throw new DecoderException("RFC 1522 violation: encoding token not found"); |
| } |
| final 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(SEP, from); |
| byte[] data = StringUtils.getBytesUsAscii(text.substring(from, to)); |
| 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; |
| } |