Java tutorial
/* * Commons eID Project. * Copyright (C) 2008-2013 FedICT. * * This is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License version * 3.0 as published by the Free Software Foundation. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this software; if not, see * http://www.gnu.org/licenses/. */ package be.fedict.commons.eid.consumer.tlv; import java.io.UnsupportedEncodingException; import java.lang.reflect.Field; import java.util.HashMap; import java.util.Map; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * Tag-Length-Value parser. The TLV-format is used in the eID card for encoding * of the identity and address files. * * @author Frank Cornelis * */ public class TlvParser { private static final Log LOG = LogFactory.getLog(TlvParser.class); private TlvParser() { super(); } /** * Parses the given file using the meta-data annotations within the tlvClass * parameter. * * @param <T> * @param file * @param tlvClass * @return */ public static <T> T parse(final byte[] file, final Class<T> tlvClass) { T t; try { t = parseThrowing(file, tlvClass); } catch (final Exception ex) { throw new RuntimeException("error parsing file: " + tlvClass.getName(), ex); } return t; } private static byte[] copy(final byte[] source, final int idx, final int count) { final byte[] result = new byte[count]; System.arraycopy(source, idx, result, 0, count); return result; } private static <T> T parseThrowing(final byte[] file, final Class<T> tlvClass) throws InstantiationException, IllegalAccessException, DataConvertorException, UnsupportedEncodingException { final Field[] fields = tlvClass.getDeclaredFields(); final Map<Integer, Field> tlvFields = new HashMap<Integer, Field>(); final T tlvObject = tlvClass.newInstance(); for (Field field : fields) { final TlvField tlvFieldAnnotation = field.getAnnotation(TlvField.class); if (null != tlvFieldAnnotation) { final int tagId = tlvFieldAnnotation.value(); if (tlvFields.containsKey(new Integer(tagId))) { throw new IllegalArgumentException("TLV field duplicate: " + tagId); } tlvFields.put(new Integer(tagId), field); } final OriginalData originalDataAnnotation = field.getAnnotation(OriginalData.class); if (null != originalDataAnnotation) { field.setAccessible(true); field.set(tlvObject, file); } } int idx = 0; while (idx < file.length - 1) { final byte tag = file[idx]; idx++; byte lengthByte = file[idx]; int length = lengthByte & 0x7f; while ((lengthByte & 0x80) == 0x80) { idx++; lengthByte = file[idx]; length = (length << 7) + (lengthByte & 0x7f); } idx++; if (0 == tag) { idx += length; continue; } if (tlvFields.containsKey(new Integer(tag))) { final Field tlvField = tlvFields.get(new Integer(tag)); final Class<?> tlvType = tlvField.getType(); final ConvertData convertDataAnnotation = tlvField.getAnnotation(ConvertData.class); final byte[] tlvValue = copy(file, idx, length); Object fieldValue; if (null != convertDataAnnotation) { final Class<? extends DataConvertor<?>> dataConvertorClass = convertDataAnnotation.value(); final DataConvertor<?> dataConvertor = dataConvertorClass.newInstance(); fieldValue = dataConvertor.convert(tlvValue); } else if (String.class == tlvType) { fieldValue = new String(tlvValue, "UTF-8"); } else if (Boolean.TYPE == tlvType) { fieldValue = true; } else if (tlvType.isArray() && Byte.TYPE == tlvType.getComponentType()) { fieldValue = tlvValue; } else { throw new IllegalArgumentException("unsupported field type: " + tlvType.getName()); } if (null != tlvField.get(tlvObject) && false == tlvField.getType().isPrimitive()) { throw new RuntimeException("field was already set: " + tlvField.getName()); } tlvField.setAccessible(true); tlvField.set(tlvObject, fieldValue); } else { LOG.debug("unknown tag: " + (tag & 0xff) + ", length: " + length); } idx += length; } return tlvObject; } }