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/*
 * 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 Standard charsets * @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 Standard charsets * @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 Standard charsets */ public BCodec(final String charsetName) { this(Charset.forName(charsetName)); } /** * 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; } @Override protected String getEncoding() { return "B"; } @Override protected byte[] doEncoding(final byte[] bytes) { if (bytes == null) { return null; } return Base64.encodeBase64(bytes); } @Override protected byte[] doDecoding(final byte[] bytes) { if (bytes == null) { return null; } return new Base64(0, BaseNCodec.getChunkSeparator(), false, decodingPolicy).decode(bytes); } /** * 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); } } /** * 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()); } /** * 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); } } /** * 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; } else if (value instanceof String) { return encode((String) value); } else { throw new EncoderException("Objects of type " + value.getClass().getName() + " cannot be encoded using BCodec"); } } /** * 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; } else if (value instanceof String) { return decode((String) value); } else { throw new DecoderException("Objects of type " + value.getClass().getName() + " cannot be decoded using BCodec"); } } /** * 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(); } }





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