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Diffstat (limited to 'src/org/apache/commons/codec/net/RFC1522Codec.java')
| -rw-r--r-- | src/org/apache/commons/codec/net/RFC1522Codec.java | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/src/org/apache/commons/codec/net/RFC1522Codec.java b/src/org/apache/commons/codec/net/RFC1522Codec.java new file mode 100644 index 0000000..0acf921 --- /dev/null +++ b/src/org/apache/commons/codec/net/RFC1522Codec.java @@ -0,0 +1,161 @@ +/* + * 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; +} |