/protocols/smpp/src/main/java/org/mobicents/protocols/smpp/encoding/AlphabetEncoding.java

  1/*
  2 * JBoss, Home of Professional Open Source
  3 * Copyright 2011, Red Hat, Inc. and individual contributors
  4 * by the @authors tag. See the copyright.txt in the distribution for a
  5 * full listing of individual contributors.
  6 *
  7 * This is free software; you can redistribute it and/or modify it
  8 * under the terms of the GNU Lesser General Public License as
  9 * published by the Free Software Foundation; either version 2.1 of
 10 * the License, or (at your option) any later version.
 11 *
 12 * This software is distributed in the hope that it will be useful,
 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 15 * Lesser General Public License for more details.
 16 *
 17 * You should have received a copy of the GNU Lesser General Public
 18 * License along with this software; if not, write to the Free
 19 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 20 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 21 */
 22
 23package org.mobicents.protocols.smpp.encoding;
 24
 25import java.io.UnsupportedEncodingException;
 26
 27import org.mobicents.protocols.smpp.SMPPRuntimeException;
 28
 29/**
 30 * SMS Alphabet to Java String mapping interface. Implementations of this
 31 * interface convert Java Unicode strings into a series of bytes representing
 32 * the String in a particular SMS alphabet.
 33 */
 34public class AlphabetEncoding extends AbstractMessageEncoding<String> {
 35    private String charset;
 36
 37    /**
 38     * Create a new alphabet encoding.
 39     * @param dcs The data coding value to be used for this encoding.
 40     */
 41    protected AlphabetEncoding(int dcs) {
 42        super(dcs);
 43    }
 44
 45    /**
 46     * Get the character set in use by this alpabet encoding (if any).
 47     * @return The character set in use by this alphabet encoding. This method
 48     * may return <code>null</code> if the implementation is not using a JVM-
 49     * supported character set.
 50     */
 51    public String getCharset() {
 52        return charset;
 53    }
 54
 55    /**
 56     * Convert SMS message text into a Java String. Implementations of this
 57     * method <b>must </b> support decoding <code>null</code>. In such cases,
 58     * the String "" will be returned.
 59     */
 60    public String decode(byte[] data) {
 61        if (data != null) {
 62            return decode(data, 0, data.length);
 63        } else {
 64            return "";
 65        }
 66    }
 67
 68    /**
 69     * Convert SMS message text into a Java String.
 70     * @param data The bytes to decode.
 71     * @param offset The offset within the data to begin decoding characters.
 72     * @param length The number of bytes to decode to characters.
 73     * @throws NullPointerException If <tt>data</tt> is <tt>null</tt>.
 74     */
 75    public String decode(byte[] data, int offset, int length) {
 76        try {
 77            if (data != null) {
 78                return new String(data, offset, length, charset);
 79            } else {
 80                throw new NullPointerException("Data cannot be null");
 81            }
 82        } catch (UnsupportedEncodingException x) {
 83            // Shouldn't happen - setCharset should have detected this.
 84            throw new RuntimeException();
 85        }
 86    }
 87
 88    /**
 89     * Convert a Java String into SMS message text. Implementations of this
 90     * method <b>must </b> support encoding a <code>null</code> string. In
 91     * such cases, a byte array of length 0 will be returned.
 92     */
 93    public byte[] encode(String string) {
 94        try {
 95            if (string != null) {
 96                return string.getBytes(charset);
 97            }
 98        } catch (UnsupportedEncodingException x) {
 99            // Shouldn't happen - setCharset should have detected this.
100            throw new RuntimeException();
101        }
102        return new byte[0];
103    }
104
105    /**
106     * Get the number of bytes a particular string would encode as on the
107     * wire.
108     * @return The number of bytes <code>string</code> would encode to.
109     */
110    public int getEncodedSize(String string) {
111        if (string != null) {
112            return encode(string).length;
113        } else {
114            return 0;
115        }
116    }
117    
118    /**
119     * Set the charset of this alphabet encoding. Sub-classes can use this
120     * to create new instances of alphabet encoding for character sets that
121     * are supported by the JVM. This method can only be called once.
122     * Subsequent calls will throw a RuntimeException.
123     * @param charset The character set to use for encoding and decoding.
124     * @throws UnsupportedEncodingException If the JVM does not support the
125     * specified character set.
126     */
127    protected void setCharset(String charset) throws UnsupportedEncodingException {
128        if (this.charset != null) {
129            throw new SMPPRuntimeException("Cannot change charset.");
130        }
131        new String("probe").getBytes(charset);
132        this.charset = charset;
133    }
134}