org.apache.commons.codec.net.BCodec Maven / Gradle / Ivy
/*
* 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 java.nio.charset.StandardCharsets;
import org.apache.commons.codec.CodecPolicy;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.EncoderException;
import org.apache.commons.codec.StringDecoder;
import org.apache.commons.codec.StringEncoder;
import org.apache.commons.codec.binary.Base64;
import org.apache.commons.codec.binary.BaseNCodec;
/**
* Identical to the Base64 encoding defined by RFC 1521
* and allows a character set to be specified.
*
* RFC 1522 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.
*
*
* This class is immutable and thread-safe.
*
*
* @see MIME (Multipurpose Internet Mail Extensions) Part Two: Message
* Header Extensions for Non-ASCII Text
*
* @since 1.3
*/
public class BCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
/**
* The default decoding policy.
*/
private static final CodecPolicy DECODING_POLICY_DEFAULT = CodecPolicy.LENIENT;
/**
* The default Charset used for string decoding and encoding.
*/
private final Charset charset;
/**
* If true then decoding should throw an exception for impossible combinations of bits at the
* end of the byte input. The default is to decode as much of them as possible.
*/
private final CodecPolicy decodingPolicy;
/**
* Default constructor.
*/
public BCodec() {
this(StandardCharsets.UTF_8);
}
/**
* Constructor which allows for the selection of a default Charset
*
* @param charset
* the default string Charset to use.
*
* @see Charset
* @since 1.7
*/
public BCodec(final Charset charset) {
this(charset, DECODING_POLICY_DEFAULT);
}
/**
* Constructor which allows for the selection of a default Charset.
*
* @param charset
* the default string Charset to use.
* @param decodingPolicy The decoding policy.
*
* @see Charset
* @since 1.15
*/
public BCodec(final Charset charset, final CodecPolicy decodingPolicy) {
this.charset = charset;
this.decodingPolicy = decodingPolicy;
}
/**
* Constructor which allows for the selection of a default Charset
*
* @param charsetName
* the default Charset to use.
* @throws java.nio.charset.UnsupportedCharsetException
* If the named Charset is unavailable
* @since 1.7 throws UnsupportedCharsetException if the named Charset is unavailable
* @see Charset
*/
public BCodec(final String charsetName) {
this(Charset.forName(charsetName));
}
/**
* Decodes a Base64 object into its original form. Escaped characters are converted back to their original
* representation.
*
* @param value
* Base64 object to convert into its original form
* @return original object
* @throws DecoderException
* Thrown if the argument is not a {@code String}. Thrown if a failure condition is encountered
* during the decode process.
*/
@Override
public Object decode(final Object value) throws DecoderException {
if (value == null) {
return null;
}
if (value instanceof String) {
return decode((String) value);
}
throw new DecoderException("Objects of type " +
value.getClass().getName() +
" cannot be decoded using BCodec");
}
/**
* Decodes a Base64 string into its original form. Escaped characters are converted back to their original
* representation.
*
* @param value
* Base64 string to convert into its original form
* @return original string
* @throws DecoderException
* A decoder exception is thrown if a failure condition is encountered during the decode process.
*/
@Override
public String decode(final String value) throws DecoderException {
if (value == null) {
return null;
}
try {
return this.decodeText(value);
} catch (final UnsupportedEncodingException | IllegalArgumentException e) {
throw new DecoderException(e.getMessage(), e);
}
}
@Override
protected byte[] doDecoding(final byte[] bytes) {
if (bytes == null) {
return null;
}
return new Base64(0, BaseNCodec.getChunkSeparator(), false, decodingPolicy).decode(bytes);
}
@Override
protected byte[] doEncoding(final byte[] bytes) {
if (bytes == null) {
return null;
}
return Base64.encodeBase64(bytes);
}
/**
* Encodes an object into its Base64 form using the default Charset. Unsafe characters are escaped.
*
* @param value
* object to convert to Base64 form
* @return Base64 object
* @throws EncoderException
* thrown if a failure condition is encountered during the encoding process.
*/
@Override
public Object encode(final Object value) throws EncoderException {
if (value == null) {
return null;
}
if (value instanceof String) {
return encode((String) value);
}
throw new EncoderException("Objects of type " +
value.getClass().getName() +
" cannot be encoded using BCodec");
}
/**
* Encodes a string into its Base64 form using the default Charset. Unsafe characters are escaped.
*
* @param strSource
* string to convert to Base64 form
* @return Base64 string
* @throws EncoderException
* thrown if a failure condition is encountered during the encoding process.
*/
@Override
public String encode(final String strSource) throws EncoderException {
if (strSource == null) {
return null;
}
return encode(strSource, this.getCharset());
}
/**
* Encodes a string into its Base64 form using the specified Charset. Unsafe characters are escaped.
*
* @param strSource
* string to convert to Base64 form
* @param sourceCharset
* the Charset for {@code value}
* @return Base64 string
* @throws EncoderException
* thrown if a failure condition is encountered during the encoding process.
* @since 1.7
*/
public String encode(final String strSource, final Charset sourceCharset) throws EncoderException {
if (strSource == null) {
return null;
}
return encodeText(strSource, sourceCharset);
}
/**
* Encodes a string into its Base64 form using the specified Charset. Unsafe characters are escaped.
*
* @param strSource
* string to convert to Base64 form
* @param sourceCharset
* the Charset for {@code value}
* @return Base64 string
* @throws EncoderException
* thrown if a failure condition is encountered during the encoding process.
*/
public String encode(final String strSource, final String sourceCharset) throws EncoderException {
if (strSource == null) {
return null;
}
try {
return this.encodeText(strSource, sourceCharset);
} catch (final UnsupportedEncodingException e) {
throw new EncoderException(e.getMessage(), e);
}
}
/**
* Gets the default Charset name used for string decoding and encoding.
*
* @return the default Charset name
* @since 1.7
*/
public Charset getCharset() {
return this.charset;
}
/**
* Gets the default Charset name used for string decoding and encoding.
*
* @return the default Charset name
*/
public String getDefaultCharset() {
return this.charset.name();
}
@Override
protected String getEncoding() {
return "B";
}
/**
* Returns true if decoding behavior is strict. Decoding will raise a
* {@link DecoderException} if trailing bits are not part of a valid Base64 encoding.
*
* The default is false for lenient encoding. Decoding will compose trailing bits
* into 8-bit bytes and discard the remainder.
*
* @return true if using strict decoding
* @since 1.15
*/
public boolean isStrictDecoding() {
return decodingPolicy == CodecPolicy.STRICT;
}
}