Java tutorial
/** * 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.camel.component.hl7; import java.nio.charset.Charset; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.DecoderException; import io.netty.handler.codec.DelimiterBasedFrameDecoder; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * HL7 MLLP Decoder for Netty4 */ class HL7MLLPNettyDecoder extends DelimiterBasedFrameDecoder { private static final Logger LOG = LoggerFactory.getLogger(HL7MLLPNettyDecoder.class); private static final int MAX_FRAME_LENGTH = Integer.MAX_VALUE; private final HL7MLLPConfig config; /** * Creates a decoder instance using a default HL7MLLPConfig */ public HL7MLLPNettyDecoder() { this(new HL7MLLPConfig()); } /** * Creates a decoder instance * * @param config HL7MLLPConfig to be used for decoding * @throws java.lang.NullPointerException is config is null */ public HL7MLLPNettyDecoder(HL7MLLPConfig config) { super(MAX_FRAME_LENGTH, true, Unpooled .copiedBuffer(new char[] { config.getEndByte1(), config.getEndByte2() }, Charset.defaultCharset())); this.config = config; } @Override protected Object decode(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception { ByteBuf buf = (ByteBuf) super.decode(ctx, buffer); if (buf != null) { int pos = buf.bytesBefore((byte) config.getStartByte()); if (pos >= 0) { ByteBuf msg = buf.readerIndex(pos + 1).slice(); LOG.debug("Message ends with length {}", msg.readableBytes()); return config.isProduceString() ? asString(msg) : asByteArray(msg); } else { throw new DecoderException("Did not find start byte " + (int) config.getStartByte()); } } // Message not complete yet - return null to be called again LOG.debug("No complete messages yet at position {}", buffer.readableBytes()); return null; } private byte[] asByteArray(ByteBuf msg) { byte[] bytes = new byte[msg.readableBytes()]; msg.getBytes(0, bytes); if (config.isConvertLFtoCR()) { for (int i = 0; i < bytes.length; i++) { if (bytes[i] == (byte) '\n') { bytes[i] = (byte) '\r'; } } } return bytes; } private String asString(ByteBuf msg) { String s = msg.toString(config.getCharset()); if (config.isConvertLFtoCR()) { return s.replace('\n', '\r'); } return s; } }