Commons Codec example source code file (QCodec.java)

This example Commons Codec source code file (QCodec.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Codec tags/keywords

bitset, blank, decoderexception, decoderexception, encoderexception, encoderexception, io, object, q, qcodec, string, string, underscore, underscore, unsupportedencodingexception, util

The Commons Codec QCodec.java source code

/*
 * 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.util.BitSet;

import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.EncoderException;
import org.apache.commons.codec.CharEncoding;
import org.apache.commons.codec.StringDecoder;
import org.apache.commons.codec.StringEncoder;

/**
 * <p>
 * Similar to the Quoted-Printable content-transfer-encoding defined in <a
 * href="http://www.ietf.org/rfc/rfc1521.txt">RFC 1521</a> and designed to allow text containing mostly ASCII
 * characters to be decipherable on an ASCII terminal without decoding.
 * </p>
 * 
 * <p>
 * <a href="http://www.ietf.org/rfc/rfc1522.txt">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.
 * </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>
 * 
 * @author Apache Software Foundation
 * @since 1.3
 * @version $Id: QCodec.java 797857 2009-07-25 23:43:33Z ggregory $
 */
public class QCodec extends RFC1522Codec implements StringEncoder, StringDecoder {
    /**
     * The default charset used for string decoding and encoding.
     */
    private final String charset;

    /**
     * BitSet of printable characters as defined in RFC 1522.
     */
    private static final BitSet PRINTABLE_CHARS = new BitSet(256);
    // Static initializer for printable chars collection
    static {
        // alpha characters
        PRINTABLE_CHARS.set(' ');
        PRINTABLE_CHARS.set('!');
        PRINTABLE_CHARS.set('"');
        PRINTABLE_CHARS.set('#');
        PRINTABLE_CHARS.set('$');
        PRINTABLE_CHARS.set('%');
        PRINTABLE_CHARS.set('&');
        PRINTABLE_CHARS.set('\'');
        PRINTABLE_CHARS.set('(');
        PRINTABLE_CHARS.set(')');
        PRINTABLE_CHARS.set('*');
        PRINTABLE_CHARS.set('+');
        PRINTABLE_CHARS.set(',');
        PRINTABLE_CHARS.set('-');
        PRINTABLE_CHARS.set('.');
        PRINTABLE_CHARS.set('/');
        for (int i = '0'; i <= '9'; i++) {
            PRINTABLE_CHARS.set(i);
        }
        PRINTABLE_CHARS.set(':');
        PRINTABLE_CHARS.set(';');
        PRINTABLE_CHARS.set('<');
        PRINTABLE_CHARS.set('>');
        PRINTABLE_CHARS.set('@');
        for (int i = 'A'; i <= 'Z'; i++) {
            PRINTABLE_CHARS.set(i);
        }
        PRINTABLE_CHARS.set('[');
        PRINTABLE_CHARS.set('\\');
        PRINTABLE_CHARS.set(']');
        PRINTABLE_CHARS.set('^');
        PRINTABLE_CHARS.set('`');
        for (int i = 'a'; i <= 'z'; i++) {
            PRINTABLE_CHARS.set(i);
        }
        PRINTABLE_CHARS.set('{');
        PRINTABLE_CHARS.set('|');
        PRINTABLE_CHARS.set('}');
        PRINTABLE_CHARS.set('~');
    }

    private static final byte BLANK = 32;

    private static final byte UNDERSCORE = 95;

    private boolean encodeBlanks = false;

    /**
     * Default constructor.
     */
    public QCodec() {
        this(CharEncoding.UTF_8);
    }

    /**
     * Constructor which allows for the selection of a default charset
     * 
     * @param charset
     *                  the default string charset to use.
     * 
     * @see <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/nio/charset/Charset.html">Standard charsets
     */
    public QCodec(final String charset) {
        super();
        this.charset = charset;
    }

    protected String getEncoding() {
        return "Q";
    }

    protected byte[] doEncoding(byte[] bytes) {
        if (bytes == null) {
            return null;
        }
        byte[] data = QuotedPrintableCodec.encodeQuotedPrintable(PRINTABLE_CHARS, bytes);
        if (this.encodeBlanks) {
            for (int i = 0; i < data.length; i++) {
                if (data[i] == BLANK) {
                    data[i] = UNDERSCORE;
                }
            }
        }
        return data;
    }

    protected byte[] doDecoding(byte[] bytes) throws DecoderException {
        if (bytes == null) {
            return null;
        }
        boolean hasUnderscores = false;
        for (int i = 0; i < bytes.length; i++) {
            if (bytes[i] == UNDERSCORE) {
                hasUnderscores = true;
                break;
            }
        }
        if (hasUnderscores) {
            byte[] tmp = new byte[bytes.length];
            for (int i = 0; i < bytes.length; i++) {
                byte b = bytes[i];
                if (b != UNDERSCORE) {
                    tmp[i] = b;
                } else {
                    tmp[i] = BLANK;
                }
            }
            return QuotedPrintableCodec.decodeQuotedPrintable(tmp);
        } 
        return QuotedPrintableCodec.decodeQuotedPrintable(bytes);       
    }

    /**
     * Encodes a string into its quoted-printable form using the specified charset. Unsafe characters are escaped.
     * 
     * @param pString
     *                  string to convert to quoted-printable form
     * @param charset
     *                  the charset for pString
     * @return quoted-printable string
     * 
     * @throws EncoderException
     *                  thrown if a failure condition is encountered during the encoding process.
     */
    public String encode(final String pString, final String charset) throws EncoderException {
        if (pString == null) {
            return null;
        }
        try {
            return encodeText(pString, charset);
        } catch (UnsupportedEncodingException e) {
            throw new EncoderException(e.getMessage(), e);
        }
    }

    /**
     * Encodes a string into its quoted-printable form using the default charset. Unsafe characters are escaped.
     * 
     * @param pString
     *                  string to convert to quoted-printable form
     * @return quoted-printable string
     * 
     * @throws EncoderException
     *                  thrown if a failure condition is encountered during the encoding process.
     */
    public String encode(String pString) throws EncoderException {
        if (pString == null) {
            return null;
        }
        return encode(pString, getDefaultCharset());
    }

    /**
     * Decodes a quoted-printable string into its original form. Escaped characters are converted back to their original
     * representation.
     * 
     * @param pString
     *                  quoted-printable 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.
     */
    public String decode(String pString) throws DecoderException {
        if (pString == null) {
            return null;
        }
        try {
            return decodeText(pString);
        } catch (UnsupportedEncodingException e) {
            throw new DecoderException(e.getMessage(), e);
        }
    }

    /**
     * Encodes an object into its quoted-printable form using the default charset. Unsafe characters are escaped.
     * 
     * @param pObject
     *                  object to convert to quoted-printable form
     * @return quoted-printable object
     * 
     * @throws EncoderException
     *                  thrown if a failure condition is encountered during the encoding process.
     */
    public Object encode(Object pObject) throws EncoderException {
        if (pObject == null) {
            return null;
        } else if (pObject instanceof String) {
            return encode((String) pObject);
        } else {
            throw new EncoderException("Objects of type " + 
                  pObject.getClass().getName() + 
                  " cannot be encoded using Q codec");
        }
    }

    /**
     * Decodes a quoted-printable object into its original form. Escaped characters are converted back to their original
     * representation.
     * 
     * @param pObject
     *                  quoted-printable 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.
     */
    public Object decode(Object pObject) throws DecoderException {
        if (pObject == null) {
            return null;
        } else if (pObject instanceof String) {
            return decode((String) pObject);
        } else {
            throw new DecoderException("Objects of type " + 
                  pObject.getClass().getName() + 
                  " cannot be decoded using Q codec");
        }
    }

    /**
     * The default charset used for string decoding and encoding.
     * 
     * @return the default string charset.
     */
    public String getDefaultCharset() {
        return this.charset;
    }

    /**
     * Tests if optional tranformation of SPACE characters is to be used
     * 
     * @return <code>true if SPACE characters are to be transformed, false otherwise
     */
    public boolean isEncodeBlanks() {
        return this.encodeBlanks;
    }

    /**
     * Defines whether optional tranformation of SPACE characters is to be used
     * 
     * @param b
     *                  <code>true if SPACE characters are to be transformed, false otherwise
     */
    public void setEncodeBlanks(boolean b) {
        this.encodeBlanks = b;
    }
}