Java example source code file (HttpResponseHandler.java)

This example Java source code file (HttpResponseHandler.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytebuf, channelfuture, channelpromise, entry, fullhttpresponse, httpresponsehandler, illegalstateexception, integer, iterator, override, simplechannelinboundhandler, sortedmap, threading, threads, timed, treemap, util

The HttpResponseHandler.java Java example source code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project 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 io.netty.example.http2.helloworld.client;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http2.HttpConversionUtil;
import io.netty.util.CharsetUtil;

import java.util.AbstractMap.SimpleEntry;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.concurrent.TimeUnit;

/**
 * Process {@link io.netty.handler.codec.http.FullHttpResponse} translated from HTTP/2 frames
 */
public class HttpResponseHandler extends SimpleChannelInboundHandler<FullHttpResponse> {

    private SortedMap<Integer, Entry streamidPromiseMap;

    public HttpResponseHandler() {
        streamidPromiseMap = new TreeMap<Integer, Entry();
    }

    /**
     * Create an association between an anticipated response stream id and a {@link io.netty.channel.ChannelPromise}
     *
     * @param streamId The stream for which a response is expected
     * @param writeFuture A future that represent the request write operation
     * @param promise The promise object that will be used to wait/notify events
     * @return The previous object associated with {@code streamId}
     * @see HttpResponseHandler#awaitResponses(long, java.util.concurrent.TimeUnit)
     */
    public Entry<ChannelFuture, ChannelPromise> put(int streamId, ChannelFuture writeFuture, ChannelPromise promise) {
        return streamidPromiseMap.put(streamId, new SimpleEntry<ChannelFuture, ChannelPromise>(writeFuture, promise));
    }

    /**
     * Wait (sequentially) for a time duration for each anticipated response
     *
     * @param timeout Value of time to wait for each response
     * @param unit Units associated with {@code timeout}
     * @see HttpResponseHandler#put(int, io.netty.channel.ChannelFuture, io.netty.channel.ChannelPromise)
     */
    public void awaitResponses(long timeout, TimeUnit unit) {
        Iterator<Entry> itr = streamidPromiseMap.entrySet().iterator();
        while (itr.hasNext()) {
            Entry<Integer, Entry entry = itr.next();
            ChannelFuture writeFuture = entry.getValue().getKey();
            if (!writeFuture.awaitUninterruptibly(timeout, unit)) {
                throw new IllegalStateException("Timed out waiting to write for stream id " + entry.getKey());
            }
            if (!writeFuture.isSuccess()) {
                throw new RuntimeException(writeFuture.cause());
            }
            ChannelPromise promise = entry.getValue().getValue();
            if (!promise.awaitUninterruptibly(timeout, unit)) {
                throw new IllegalStateException("Timed out waiting for response on stream id " + entry.getKey());
            }
            if (!promise.isSuccess()) {
                throw new RuntimeException(promise.cause());
            }
            System.out.println("---Stream id: " + entry.getKey() + " received---");
            itr.remove();
        }
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, FullHttpResponse msg) throws Exception {
        Integer streamId = msg.headers().getInt(HttpConversionUtil.ExtensionHeaderNames.STREAM_ID.text());
        if (streamId == null) {
            System.err.println("HttpResponseHandler unexpected message received: " + msg);
            return;
        }

        Entry<ChannelFuture, ChannelPromise> entry = streamidPromiseMap.get(streamId);
        if (entry == null) {
            System.err.println("Message received for unknown stream id " + streamId);
        } else {
            // Do stuff with the message (for now just print it)
            ByteBuf content = msg.content();
            if (content.isReadable()) {
                int contentLength = content.readableBytes();
                byte[] arr = new byte[contentLength];
                content.readBytes(arr);
                System.out.println(new String(arr, 0, contentLength, CharsetUtil.UTF_8));
            }

            entry.getValue().setSuccess();
        }
    }
}