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Java example source code file (Http2ClientUpgradeCodec.java)

This example Java source code file (Http2ClientUpgradeCodec.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, charsequence, collection, exception, http2clientupgradecodec, http2connectionhandler, http2settings, http_upgrade_protocol_name, httprequest, list, override, setting_entry_length, string, upgrade_headers, util

The Http2ClientUpgradeCodec.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.handler.codec.http2;

import static io.netty.handler.codec.base64.Base64Dialect.URL_SAFE;
import static io.netty.handler.codec.http2.Http2CodecUtil.HTTP_UPGRADE_PROTOCOL_NAME;
import static io.netty.handler.codec.http2.Http2CodecUtil.HTTP_UPGRADE_SETTINGS_HEADER;
import static io.netty.handler.codec.http2.Http2CodecUtil.SETTING_ENTRY_LENGTH;
import static io.netty.handler.codec.http2.Http2CodecUtil.writeUnsignedInt;
import static io.netty.handler.codec.http2.Http2CodecUtil.writeUnsignedShort;
import static io.netty.util.CharsetUtil.UTF_8;
import static io.netty.util.ReferenceCountUtil.release;
import static io.netty.util.internal.ObjectUtil.checkNotNull;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.base64.Base64;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpClientUpgradeHandler;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.util.collection.CharObjectMap;
import io.netty.util.internal.UnstableApi;

import java.util.Collection;
import java.util.Collections;
import java.util.List;

/**
 * Client-side cleartext upgrade codec from HTTP to HTTP/2.
 */
@UnstableApi
public class Http2ClientUpgradeCodec implements HttpClientUpgradeHandler.UpgradeCodec {

    private static final List<CharSequence> UPGRADE_HEADERS = Collections.singletonList(HTTP_UPGRADE_SETTINGS_HEADER);

    private final String handlerName;
    private final Http2ConnectionHandler connectionHandler;

    /**
     * Creates the codec using a default name for the connection handler when adding to the
     * pipeline.
     *
     * @param connectionHandler the HTTP/2 connection handler
     */
    public Http2ClientUpgradeCodec(Http2ConnectionHandler connectionHandler) {
        this(null, connectionHandler);
    }

    /**
     * Creates the codec providing an upgrade to the given handler for HTTP/2.
     *
     * @param handlerName the name of the HTTP/2 connection handler to be used in the pipeline,
     *                    or {@code null} to auto-generate the name
     * @param connectionHandler the HTTP/2 connection handler
     */
    public Http2ClientUpgradeCodec(String handlerName, Http2ConnectionHandler connectionHandler) {
        this.handlerName = handlerName;
        this.connectionHandler = checkNotNull(connectionHandler, "connectionHandler");
    }

    @Override
    public CharSequence protocol() {
        return HTTP_UPGRADE_PROTOCOL_NAME;
    }

    @Override
    public Collection<CharSequence> setUpgradeHeaders(ChannelHandlerContext ctx,
            HttpRequest upgradeRequest) {
        CharSequence settingsValue = getSettingsHeaderValue(ctx);
        upgradeRequest.headers().set(HTTP_UPGRADE_SETTINGS_HEADER, settingsValue);
        return UPGRADE_HEADERS;
    }

    @Override
    public void upgradeTo(ChannelHandlerContext ctx, FullHttpResponse upgradeResponse)
            throws Exception {
        // Reserve local stream 1 for the response.
        connectionHandler.onHttpClientUpgrade();

        // Add the handler to the pipeline.
        ctx.pipeline().addAfter(ctx.name(), handlerName, connectionHandler);
    }

    /**
     * Converts the current settings for the handler to the Base64-encoded representation used in
     * the HTTP2-Settings upgrade header.
     */
    private CharSequence getSettingsHeaderValue(ChannelHandlerContext ctx) {
        ByteBuf buf = null;
        ByteBuf encodedBuf = null;
        try {
            // Get the local settings for the handler.
            Http2Settings settings = connectionHandler.decoder().localSettings();

            // Serialize the payload of the SETTINGS frame.
            int payloadLength = SETTING_ENTRY_LENGTH * settings.size();
            buf = ctx.alloc().buffer(payloadLength);
            for (CharObjectMap.PrimitiveEntry<Long> entry : settings.entries()) {
                writeUnsignedShort(entry.key(), buf);
                writeUnsignedInt(entry.value(), buf);
            }

            // Base64 encode the payload and then convert to a string for the header.
            encodedBuf = Base64.encode(buf, URL_SAFE);
            return encodedBuf.toString(UTF_8);
        } finally {
            release(buf);
            release(encodedBuf);
        }
    }
}

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