Java tutorial
/* * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.netconf.nettyutil.handler; import com.google.common.base.Preconditions; import io.netty.buffer.ByteBuf; import io.netty.buffer.ByteBufOutputStream; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.MessageToByteEncoder; import java.io.IOException; import java.io.OutputStream; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerException; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.sax.SAXResult; import org.opendaylight.netconf.api.NetconfMessage; import org.openexi.proc.common.EXIOptionsException; import org.openexi.sax.Transmogrifier; import org.openexi.sax.TransmogrifierException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.xml.sax.ContentHandler; public final class NetconfMessageToEXIEncoder extends MessageToByteEncoder<NetconfMessage> { private static final Logger LOG = LoggerFactory.getLogger(NetconfMessageToEXIEncoder.class); /** * This class is not marked as shared, so it can be attached to only a single channel, * which means that {@link #encode(ChannelHandlerContext, NetconfMessage, ByteBuf)} * cannot be invoked concurrently. Hence we can reuse the transmogrifier. */ private final Transmogrifier transmogrifier; private NetconfMessageToEXIEncoder(final Transmogrifier transmogrifier) { this.transmogrifier = Preconditions.checkNotNull(transmogrifier); } public static NetconfMessageToEXIEncoder create(final NetconfEXICodec codec) throws EXIOptionsException, TransmogrifierException { return new NetconfMessageToEXIEncoder(codec.getTransmogrifier()); } @Override protected void encode(final ChannelHandlerContext ctx, final NetconfMessage msg, final ByteBuf out) throws EXIOptionsException, IOException, TransformerException, TransmogrifierException { LOG.trace("Sent to encode : {}", msg); try (final OutputStream os = new ByteBufOutputStream(out)) { transmogrifier.setOutputStream(os); final ContentHandler handler = transmogrifier.getSAXTransmogrifier(); final Transformer transformer = ThreadLocalTransformers.getDefaultTransformer(); transformer.transform(new DOMSource(msg.getDocument()), new SAXResult(handler)); } finally { // Make sure we do not retain any reference to state by removing // the output stream reference and resetting internal state. transmogrifier.setOutputStream(null); transmogrifier.getSAXTransmogrifier(); } } }