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Java example source code file (Bootstrap.java)

This example Java source code file (Bootstrap.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

addressresolvergroup, bootstrap, bootstrapconfig, channelfuture, channelpromise, default_resolver, exception, inetsocketaddress, net, network, nullpointerexception, object, override, socketaddress, suppresswarnings, throwable, util

The Bootstrap.java Java example source code

/*
 * Copyright 2012 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.bootstrap;

import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.ChannelPromise;
import io.netty.channel.EventLoop;
import io.netty.channel.EventLoopGroup;
import io.netty.resolver.AddressResolver;
import io.netty.resolver.DefaultAddressResolverGroup;
import io.netty.resolver.NameResolver;
import io.netty.resolver.AddressResolverGroup;
import io.netty.util.AttributeKey;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.FutureListener;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.Map;
import java.util.Map.Entry;

/**
 * A {@link Bootstrap} that makes it easy to bootstrap a {@link Channel} to use
 * for clients.
 *
 * <p>The {@link #bind()} methods are useful in combination with connectionless transports such as datagram (UDP).
 * For regular TCP connections, please use the provided {@link #connect()} methods.</p>
 */
public class Bootstrap extends AbstractBootstrap<Bootstrap, Channel> {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(Bootstrap.class);

    private static final AddressResolverGroup<?> DEFAULT_RESOLVER = DefaultAddressResolverGroup.INSTANCE;

    private final BootstrapConfig config = new BootstrapConfig(this);

    @SuppressWarnings("unchecked")
    private volatile AddressResolverGroup<SocketAddress> resolver =
            (AddressResolverGroup<SocketAddress>) DEFAULT_RESOLVER;
    private volatile SocketAddress remoteAddress;

    public Bootstrap() { }

    private Bootstrap(Bootstrap bootstrap) {
        super(bootstrap);
        resolver = bootstrap.resolver;
        remoteAddress = bootstrap.remoteAddress;
    }

    /**
     * Sets the {@link NameResolver} which will resolve the address of the unresolved named address.
     *
     * @param resolver the {@link NameResolver} for this {@code Bootstrap}; may be {@code null}, in which case a default
     *                 resolver will be used
     *
     * @see io.netty.resolver.DefaultAddressResolverGroup
     */
    @SuppressWarnings("unchecked")
    public Bootstrap resolver(AddressResolverGroup<?> resolver) {
        this.resolver = (AddressResolverGroup<SocketAddress>) (resolver == null ? DEFAULT_RESOLVER : resolver);
        return this;
    }

    /**
     * The {@link SocketAddress} to connect to once the {@link #connect()} method
     * is called.
     */
    public Bootstrap remoteAddress(SocketAddress remoteAddress) {
        this.remoteAddress = remoteAddress;
        return this;
    }

    /**
     * @see {@link #remoteAddress(SocketAddress)}
     */
    public Bootstrap remoteAddress(String inetHost, int inetPort) {
        remoteAddress = InetSocketAddress.createUnresolved(inetHost, inetPort);
        return this;
    }

    /**
     * @see {@link #remoteAddress(SocketAddress)}
     */
    public Bootstrap remoteAddress(InetAddress inetHost, int inetPort) {
        remoteAddress = new InetSocketAddress(inetHost, inetPort);
        return this;
    }

    /**
     * Connect a {@link Channel} to the remote peer.
     */
    public ChannelFuture connect() {
        validate();
        SocketAddress remoteAddress = this.remoteAddress;
        if (remoteAddress == null) {
            throw new IllegalStateException("remoteAddress not set");
        }

        return doResolveAndConnect(remoteAddress, config.localAddress());
    }

    /**
     * Connect a {@link Channel} to the remote peer.
     */
    public ChannelFuture connect(String inetHost, int inetPort) {
        return connect(InetSocketAddress.createUnresolved(inetHost, inetPort));
    }

    /**
     * Connect a {@link Channel} to the remote peer.
     */
    public ChannelFuture connect(InetAddress inetHost, int inetPort) {
        return connect(new InetSocketAddress(inetHost, inetPort));
    }

    /**
     * Connect a {@link Channel} to the remote peer.
     */
    public ChannelFuture connect(SocketAddress remoteAddress) {
        if (remoteAddress == null) {
            throw new NullPointerException("remoteAddress");
        }

        validate();
        return doResolveAndConnect(remoteAddress, config.localAddress());
    }

    /**
     * Connect a {@link Channel} to the remote peer.
     */
    public ChannelFuture connect(SocketAddress remoteAddress, SocketAddress localAddress) {
        if (remoteAddress == null) {
            throw new NullPointerException("remoteAddress");
        }
        validate();
        return doResolveAndConnect(remoteAddress, localAddress);
    }

    /**
     * @see {@link #connect()}
     */
    private ChannelFuture doResolveAndConnect(final SocketAddress remoteAddress, final SocketAddress localAddress) {
        final ChannelFuture regFuture = initAndRegister();
        final Channel channel = regFuture.channel();

        if (regFuture.isDone()) {
            if (!regFuture.isSuccess()) {
                return regFuture;
            }
            return doResolveAndConnect0(channel, remoteAddress, localAddress, channel.newPromise());
        } else {
            // Registration future is almost always fulfilled already, but just in case it's not.
            final PendingRegistrationPromise promise = new PendingRegistrationPromise(channel);
            regFuture.addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) throws Exception {
                    // Direclty obtain the cause and do a null check so we only need one volatile read in case of a
                    // failure.
                    Throwable cause = future.cause();
                    if (cause != null) {
                        // Registration on the EventLoop failed so fail the ChannelPromise directly to not cause an
                        // IllegalStateException once we try to access the EventLoop of the Channel.
                        promise.setFailure(cause);
                    } else {
                        // Registration was successful, so set the correct executor to use.
                        // See https://github.com/netty/netty/issues/2586
                        promise.registered();
                        doResolveAndConnect0(channel, remoteAddress, localAddress, promise);
                    }
                }
            });
            return promise;
        }
    }

    private ChannelFuture doResolveAndConnect0(final Channel channel, SocketAddress remoteAddress,
                                               final SocketAddress localAddress, final ChannelPromise promise) {
        try {
            final EventLoop eventLoop = channel.eventLoop();
            final AddressResolver<SocketAddress> resolver = this.resolver.getResolver(eventLoop);

            if (!resolver.isSupported(remoteAddress) || resolver.isResolved(remoteAddress)) {
                // Resolver has no idea about what to do with the specified remote address or it's resolved already.
                doConnect(remoteAddress, localAddress, promise);
                return promise;
            }

            final Future<SocketAddress> resolveFuture = resolver.resolve(remoteAddress);

            if (resolveFuture.isDone()) {
                final Throwable resolveFailureCause = resolveFuture.cause();

                if (resolveFailureCause != null) {
                    // Failed to resolve immediately
                    channel.close();
                    promise.setFailure(resolveFailureCause);
                } else {
                    // Succeeded to resolve immediately; cached? (or did a blocking lookup)
                    doConnect(resolveFuture.getNow(), localAddress, promise);
                }
                return promise;
            }

            // Wait until the name resolution is finished.
            resolveFuture.addListener(new FutureListener<SocketAddress>() {
                @Override
                public void operationComplete(Future<SocketAddress> future) throws Exception {
                    if (future.cause() != null) {
                        channel.close();
                        promise.setFailure(future.cause());
                    } else {
                        doConnect(future.getNow(), localAddress, promise);
                    }
                }
            });
        } catch (Throwable cause) {
            promise.tryFailure(cause);
        }
        return promise;
    }

    private static void doConnect(
            final SocketAddress remoteAddress, final SocketAddress localAddress, final ChannelPromise connectPromise) {

        // This method is invoked before channelRegistered() is triggered.  Give user handlers a chance to set up
        // the pipeline in its channelRegistered() implementation.
        final Channel channel = connectPromise.channel();
        channel.eventLoop().execute(new Runnable() {
            @Override
            public void run() {
                if (localAddress == null) {
                    channel.connect(remoteAddress, connectPromise);
                } else {
                    channel.connect(remoteAddress, localAddress, connectPromise);
                }
                connectPromise.addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
            }
        });
    }

    @Override
    @SuppressWarnings("unchecked")
    void init(Channel channel) throws Exception {
        ChannelPipeline p = channel.pipeline();
        p.addLast(config.handler());

        final Map<ChannelOption options = options0();
        synchronized (options) {
            for (Entry<ChannelOption e: options.entrySet()) {
                try {
                    if (!channel.config().setOption((ChannelOption<Object>) e.getKey(), e.getValue())) {
                        logger.warn("Unknown channel option: " + e);
                    }
                } catch (Throwable t) {
                    logger.warn("Failed to set a channel option: " + channel, t);
                }
            }
        }

        final Map<AttributeKey attrs = attrs0();
        synchronized (attrs) {
            for (Entry<AttributeKey e: attrs.entrySet()) {
                channel.attr((AttributeKey<Object>) e.getKey()).set(e.getValue());
            }
        }
    }

    @Override
    public Bootstrap validate() {
        super.validate();
        if (config.handler() == null) {
            throw new IllegalStateException("handler not set");
        }
        return this;
    }

    @Override
    @SuppressWarnings("CloneDoesntCallSuperClone")
    public Bootstrap clone() {
        return new Bootstrap(this);
    }

    /**
     * Returns a deep clone of this bootstrap which has the identical configuration except that it uses
     * the given {@link EventLoopGroup}. This method is useful when making multiple {@link Channel}s with similar
     * settings.
     */
    public Bootstrap clone(EventLoopGroup group) {
        Bootstrap bs = new Bootstrap(this);
        bs.group = group;
        return bs;
    }

    @Override
    public final BootstrapConfig config() {
        return config;
    }

    final SocketAddress remoteAddress() {
        return remoteAddress;
    }

    final AddressResolverGroup<?> resolver() {
        return resolver;
    }
}

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