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.hadoop.hdfs.server.datanode.web.webhdfs; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.handler.codec.http.DefaultHttpResponse; import io.netty.handler.codec.http.HttpContent; import io.netty.handler.codec.http.LastHttpContent; import org.apache.commons.logging.Log; import org.apache.hadoop.hdfs.DFSClient; import org.apache.hadoop.io.IOUtils; import java.io.IOException; import java.io.OutputStream; import static io.netty.handler.codec.http.HttpHeaders.Names.CONNECTION; import static io.netty.handler.codec.http.HttpHeaders.Values.CLOSE; class HdfsWriter extends SimpleChannelInboundHandler<HttpContent> { private final DFSClient client; private final OutputStream out; private final DefaultHttpResponse response; private static final Log LOG = WebHdfsHandler.LOG; HdfsWriter(DFSClient client, OutputStream out, DefaultHttpResponse response) { this.client = client; this.out = out; this.response = response; } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } @Override protected void channelRead0(ChannelHandlerContext ctx, HttpContent chunk) throws IOException { chunk.content().readBytes(out, chunk.content().readableBytes()); if (chunk instanceof LastHttpContent) { response.headers().set(CONNECTION, CLOSE); ctx.write(response).addListener(ChannelFutureListener.CLOSE); releaseDfsResources(); } } @Override public void channelInactive(ChannelHandlerContext ctx) { releaseDfsResources(); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { releaseDfsResources(); DefaultHttpResponse resp = ExceptionHandler.exceptionCaught(cause); resp.headers().set(CONNECTION, CLOSE); ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE); } private void releaseDfsResources() { IOUtils.cleanup(LOG, out); IOUtils.cleanup(LOG, client); } }