Java tutorial
package org.wso2.carbon.inbound.endpoint.protocol.hl7.codec; /** * Copyright (c) 2015, WSO2 Inc. (http://www.wso2.org) All Rights Reserved. * * WSO2 Inc. 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. */ import ca.uhn.hl7v2.HL7Exception; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.wso2.carbon.inbound.endpoint.protocol.hl7.context.MLLPContext; import org.wso2.carbon.inbound.endpoint.protocol.hl7.core.MLLPConstants; import org.wso2.carbon.inbound.endpoint.protocol.hl7.core.MLLProtocolException; import org.wso2.carbon.inbound.endpoint.protocol.hl7.util.HL7MessageUtils; import java.io.IOException; import java.nio.ByteBuffer; import java.nio.charset.CharsetDecoder; public class HL7Codec { private static final Log log = LogFactory.getLog(HL7Codec.class); public static final int READ_HEADER = 0; public static final int READ_CONTENT = 1; public static final int READ_TRAILER = 2; public static final int READ_COMPLETE = 3; public static final int WRITE_HEADER = 4; public static final int WRITE_CONTENT = 5; public static final int WRITE_TRAILER = 6; public static final int WRITE_COMPLETE = 7; private CharsetDecoder charsetDecoder; private volatile int state; private int responseReadPosition = 0; private byte[] responseBytes = null; public HL7Codec() { this.state = READ_HEADER; this.charsetDecoder = MLLPConstants.UTF8_CHARSET.newDecoder(); } public HL7Codec(CharsetDecoder charsetDecoder) { this.state = READ_HEADER; setCharsetDecoder(charsetDecoder); } public int decode(ByteBuffer dst, MLLPContext context) throws IOException, MLLProtocolException, HL7Exception { if (this.state >= READ_COMPLETE || dst.position() < 0) { return -1; } if (this.state == READ_HEADER) { if (dst.get(0) == MLLPConstants.HL7_HEADER[0]) { dst.position(1); this.state = READ_CONTENT; } else { throw new MLLProtocolException("Could not find header in incoming message."); } } if (this.state == READ_CONTENT) { int trailerIndex = findTrailer(dst); if (trailerIndex > -1) { dst.limit(trailerIndex); this.state = READ_TRAILER; } context.getRequestBuffer().append(charsetDecoder.decode(dst).toString()); } if (this.state == READ_TRAILER) { this.state = READ_COMPLETE; try { if (context.isPreProcess()) { context.setHl7Message(HL7MessageUtils.parse(context.getRequestBuffer().toString(), context.getPreProcessParser())); } else { context.setHl7Message(HL7MessageUtils.parse(context.getRequestBuffer().toString(), context.isValidateMessage())); } context.getRequestBuffer().setLength(0); } catch (HL7Exception e) { log.error("Error while parsing request message: " + context.getRequestBuffer()); throw e; } } return 0; } private int findTrailer(ByteBuffer dst) { for (int i = 0; i < dst.limit(); i++) { if (dst.get(i) == MLLPConstants.HL7_TRAILER[0]) { if (dst.get(i + 1) == MLLPConstants.HL7_TRAILER[1]) { return i - 1; } } } return -1; } public int encode(ByteBuffer outBuf, MLLPContext context) throws HL7Exception, IOException { if (this.state < READ_COMPLETE) { return 0; } if (this.state == READ_COMPLETE) { if ((context.isAutoAck() || context.isApplicationAck()) && !context.isNackMode()) { responseBytes = context.getHl7Message().generateACK().encode().getBytes(charsetDecoder.charset()); context.setApplicationAck(false); } else { responseBytes = context.getHl7Message().encode().getBytes(charsetDecoder.charset()); } this.state = WRITE_HEADER; } if (this.state >= WRITE_HEADER) { return fillBuffer(outBuf, responseBytes); } return 0; } private int fillBuffer(ByteBuffer byteBuffer, byte[] responseBytes) { if (responseBytes == null) { return 0; } byte b; int count = 0; int headerPosition = 0; if (this.state == WRITE_HEADER) { byteBuffer.put(MLLPConstants.HL7_HEADER[0]); headerPosition = 1; this.state = WRITE_CONTENT; } int MAX = byteBuffer.capacity(); if (byteBuffer.capacity() - (responseBytes.length - responseReadPosition + headerPosition) > 0) { MAX = responseBytes.length - responseReadPosition + headerPosition; } for (int i = responseReadPosition; i < MAX + responseReadPosition - headerPosition; i++) { count++; b = responseBytes[i]; byteBuffer.put(b); } responseReadPosition += count; if (responseReadPosition == responseBytes.length) { this.state = WRITE_TRAILER; responseReadPosition = 0; } byteBuffer.flip(); return count; } public boolean isReadComplete() { if (this.state >= READ_COMPLETE) { return true; } return false; } public boolean isWriteTrailer() { if (this.state == WRITE_TRAILER) { return true; } return false; } public boolean isWriteComplete() { if (this.state == WRITE_COMPLETE) { return true; } return false; } public int getState() { return state; } public void setState(int state) { this.state = state; } public CharsetDecoder getCharsetDecoder() { return charsetDecoder; } private void setCharsetDecoder(CharsetDecoder charsetDecoder) { this.charsetDecoder = charsetDecoder; } }