learn netty 1

实现server遇阻。回头学习一下netty自带的一个http server实现。


A ChannelEvent is handled by a list of ChannelHandlers in a ChannelPipeline.The pipeline
implements an advanced form of the Intercepting Filter pattern to give a user full control over how an event
is handled and how the handlers in the pipeline interact with each other.

整体结构见图。

public class MyReadHandler implements SimpleChannelHandler {
public void messageReceived(ChannelHandlerContext ctx, MessageEvent evt) {
Object message = evt.getMessage();
// Do something with the received message.
...
// And forward the event to the next handler.
ctx.sendUpstream(evt);
}
}

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005-2008, Red Hat Middleware LLC, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.netty.example.http;

import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.ChannelFactory;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;

/**
 * @author The Netty Project ([email protected])
 * @author Andy Taylor ([email protected])
 */
public class HttpServer {
    public static void main(String[] args) {
        // Configure the server.
        ChannelFactory factory =
              new NioServerSocketChannelFactory(
                    Executors.newCachedThreadPool(),
                    Executors.newCachedThreadPool());

        ServerBootstrap bootstrap = new ServerBootstrap(factory);
       //[color=red]设置管道[/color]
        bootstrap.setPipelineFactory(new HttpServerPipelineFactory());

        bootstrap.setOption("child.tcpNoDelay", true);
        bootstrap.setOption("child.keepAlive", true);

        // Bind and start to accept incoming connections.
        bootstrap.bind(new InetSocketAddress(8080));
    }
}

管道实现类

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005-2008, Red Hat Middleware LLC, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.netty.example.http;

import static org.jboss.netty.channel.Channels.*;

import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.handler.codec.http.HttpRequestDecoder;
import org.jboss.netty.handler.codec.http.HttpResponseEncoder;

/**
 * @author The Netty Project ([email protected])
 * @author Andy Taylor ([email protected])
 */
public class HttpServerPipelineFactory implements ChannelPipelineFactory {
    public ChannelPipeline getPipeline() throws Exception {
        // Create a default pipeline implementation.
        ChannelPipeline pipeline = pipeline();

        // Uncomment the following line if you want HTTPS
        //SSLEngine engine = SecureChatSslContextFactory.getServerContext().createSSLEngine();
        //engine.setUseClientMode(false);
        //pipeline.addLast("ssl", new SslHandler(engine));

        pipeline.addLast("decoder", new HttpRequestDecoder());
        // Uncomment the following line if you don't want to handle HttpChunks.
        //pipeline.addLast("aggregator", new HttpChunkAggregator(1048576));
        pipeline.addLast("encoder", new HttpResponseEncoder());

        //[color=red]加入自定义handler[/color]
        pipeline.addLast("handler", new HttpRequestHandler());
        return pipeline;
    }
}

自定义handler类

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005-2008, Red Hat Middleware LLC, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.netty.example.http;

import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelFutureListener;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipelineCoverage;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
import org.jboss.netty.handler.codec.http.Cookie;
import org.jboss.netty.handler.codec.http.CookieDecoder;
import org.jboss.netty.handler.codec.http.CookieEncoder;
import org.jboss.netty.handler.codec.http.DefaultHttpResponse;
import org.jboss.netty.handler.codec.http.HttpChunk;
import org.jboss.netty.handler.codec.http.HttpHeaders;
import org.jboss.netty.handler.codec.http.HttpRequest;
import org.jboss.netty.handler.codec.http.HttpResponse;
import org.jboss.netty.handler.codec.http.HttpResponseStatus;
import org.jboss.netty.handler.codec.http.HttpVersion;
import org.jboss.netty.handler.codec.http.QueryStringDecoder;

/**
 * @author The Netty Project ([email protected])
 * @author Andy Taylor ([email protected])
 */
@ChannelPipelineCoverage("one")
public class HttpRequestHandler extends SimpleChannelUpstreamHandler {

    private volatile HttpRequest request;
    private volatile boolean readingChunks;
    private final StringBuilder responseContent = new StringBuilder();

    @Override
    public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
        if (!readingChunks) {
            HttpRequest request = this.request = (HttpRequest) e.getMessage();
            responseContent.append("WELCOME TO THE WILD WILD WEB SERVER\r\n");
            responseContent.append("===================================\r\n");

            responseContent.append("VERSION: " + request.getProtocolVersion().getText() + "\r\n");

            if (request.containsHeader(HttpHeaders.Names.HOST)) {
                responseContent.append("HOSTNAME: " + request.getHeader(HttpHeaders.Names.HOST) + "\r\n");
            }

            responseContent.append("REQUEST_URI: " + request.getUri() + "\r\n\r\n");

            if (!request.getHeaderNames().isEmpty()) {
                for (String name: request.getHeaderNames()) {
                    for (String value: request.getHeaders(name)) {
                        responseContent.append("HEADER: " + name + " = " + value + "\r\n");
                    }
                }
                responseContent.append("\r\n");
            }

            QueryStringDecoder queryStringDecoder = new QueryStringDecoder(request.getUri());
            Map<String, List<String>> params = queryStringDecoder.getParameters();
            if (!params.isEmpty()) {
                for (Entry<String, List<String>> p: params.entrySet()) {
                    String key = p.getKey();
                    List<String> vals = p.getValue();
                    for (String val : vals) {
                        responseContent.append("PARAM: " + key + " = " + val + "\r\n");
                    }
                }
                responseContent.append("\r\n");
            }

            if (request.isChunked()) {
                readingChunks = true;
            } else {
                ChannelBuffer content = request.getContent();
                if (content.readable()) {
                    responseContent.append("CONTENT: " + content.toString("UTF-8") + "\r\n");
                }
                writeResponse(e);
            }
        } else {
            HttpChunk chunk = (HttpChunk) e.getMessage();
            if (chunk.isLast()) {
                readingChunks = false;
                responseContent.append("END OF CONTENT\r\n");
                writeResponse(e);
            } else {
                responseContent.append("CHUNK: " + chunk.getContent().toString("UTF-8") + "\r\n");
            }
        }
    }

    private void writeResponse(MessageEvent e) {
        // Convert the response content to a ChannelBuffer.
        ChannelBuffer buf = ChannelBuffers.copiedBuffer(responseContent.toString(), "UTF-8");
        responseContent.setLength(0);

        // Decide whether to close the connection or not.
        boolean close =
            HttpHeaders.Values.CLOSE.equalsIgnoreCase(request.getHeader(HttpHeaders.Names.CONNECTION)) ||
            request.getProtocolVersion().equals(HttpVersion.HTTP_1_0) &&
            !HttpHeaders.Values.KEEP_ALIVE.equalsIgnoreCase(request.getHeader(HttpHeaders.Names.CONNECTION));

        // Build the response object.
        HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
        response.setContent(buf);
        response.setHeader(HttpHeaders.Names.CONTENT_TYPE, "text/plain; charset=UTF-8");
        response.setHeader(HttpHeaders.Names.CONTENT_LENGTH, String.valueOf(buf.readableBytes()));

        String cookieString = request.getHeader(HttpHeaders.Names.COOKIE);
        if (cookieString != null) {
            CookieDecoder cookieDecoder = new CookieDecoder();
            Set<Cookie> cookies = cookieDecoder.decode(cookieString);
            if(!cookies.isEmpty()) {
                // Reset the cookies if necessary.
                CookieEncoder cookieEncoder = new CookieEncoder(true);
                for (Cookie cookie : cookies) {
                    cookieEncoder.addCookie(cookie);
                }
                response.addHeader(HttpHeaders.Names.SET_COOKIE, cookieEncoder.encode());
            }
        }

        // Write the response.
        ChannelFuture future = e.getChannel().write(response);

        // Close the connection after the write operation is done if necessary.
        if (close) {
            future.addListener(ChannelFutureListener.CLOSE);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e)
            throws Exception {
        e.getCause().printStackTrace();
        e.getChannel().close();
    }
}

需要进一步了解

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