Netty 构建HTTP服务器示例

netty 网络通信示例一 ：http://donald-draper.iteye.com/blog/2383326
netty 网络通信示例二：http://donald-draper.iteye.com/blog/2383328
netty 网络通信示例三：http://donald-draper.iteye.com/blog/2383392
netty 网络通信示例四：http://donald-draper.iteye.com/blog/2383472
前面文章我们在编码器与解码器的示例，及基于textline编解码器通信示例，今天我们通过
Netty来时实现一个简单的HTTP服务器：
HTTP服务器：

package netty.main.http;

import java.net.InetSocketAddress;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.SslContextBuilder;
import io.netty.handler.ssl.util.SelfSignedCertificate;
import netty.initializer.http.HttpHelloWorldServerInitializer;

/**
 * An HTTP server that sends back the content of the received HTTP request
 * in a pretty plaintext form.
 * 
 * @author donald
 * 2017年6月30日
 * 上午11:44:43
 */
public final class HttpHelloWorldServer {
	private static final Logger log = LoggerFactory.getLogger(HttpHelloWorldServer.class);
    static final boolean SSL = System.getProperty("ssl") != null;
    private static final  String ip = "192.168.31.153";
    static final int port = Integer.parseInt(System.getProperty("port", SSL? "8443" : "8080"));

    public static void main(String[] args) throws Exception {
        // Configure SSL.
        final SslContext sslCtx;
        if (SSL) {
            SelfSignedCertificate ssc = new SelfSignedCertificate();
            sslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey()).build();
        } else {
            sslCtx = null;
        }

        // Configure the server.
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();
        try {
            ServerBootstrap b = new ServerBootstrap();
            b.option(ChannelOption.SO_BACKLOG, 1024);
            b.group(bossGroup, workerGroup)
             .channel(NioServerSocketChannel.class)
             .handler(new LoggingHandler(LogLevel.INFO))
             .childHandler(new HttpHelloWorldServerInitializer(sslCtx));
            InetSocketAddress inetSocketAddress = new InetSocketAddress(ip,port);
            Channel ch = b.bind(inetSocketAddress).sync().channel();
            log.info("=========HttpServer is start=========");
            System.err.println("Open your web browser and navigate to " +
                    (SSL? "https" : "http") + "://"+ip+":" + port + '/');
            ch.closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

Http服务器处理器Initializer：

package netty.initializer.http;

import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.HttpServerExpectContinueHandler;
import io.netty.handler.ssl.SslContext;
import netty.handler.http.HttpHelloWorldServerHandler;
/**
 * 
 * @author donald
 * 2017年6月30日
 * 上午11:42:49
 */
public class HttpHelloWorldServerInitializer extends ChannelInitializer<SocketChannel> {

    private final SslContext sslCtx;

    public HttpHelloWorldServerInitializer(SslContext sslCtx) {
        this.sslCtx = sslCtx;
    }

    @Override
    public void initChannel(SocketChannel ch) {
        ChannelPipeline p = ch.pipeline();
        if (sslCtx != null) {
            p.addLast(sslCtx.newHandler(ch.alloc()));
        }
        p.addLast(new HttpServerCodec());
        p.addLast(new HttpServerExpectContinueHandler());
        p.addLast(new HttpHelloWorldServerHandler());
    }
}

Http服务器处理器：

package netty.handler.http;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpUtil;
import io.netty.handler.codec.http.HttpRequest;
import io.netty.util.AsciiString;
import static io.netty.handler.codec.http.HttpResponseStatus.*;
import static io.netty.handler.codec.http.HttpVersion.*;

public class HttpHelloWorldServerHandler extends ChannelInboundHandlerAdapter {
    private static final byte[] CONTENT = { 'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd' };
    private static final AsciiString CONTENT_TYPE = new AsciiString("Content-Type");
    private static final AsciiString CONTENT_LENGTH = new AsciiString("Content-Length");
    private static final AsciiString CONNECTION = new AsciiString("Connection");
    private static final AsciiString KEEP_ALIVE = new AsciiString("keep-alive");

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        if (msg instanceof HttpRequest) {
            HttpRequest req = (HttpRequest) msg;

            boolean keepAlive = HttpUtil.isKeepAlive(req);
            FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK, Unpooled.wrappedBuffer(CONTENT));
            response.headers().set(CONTENT_TYPE, "text/plain");
            response.headers().setInt(CONTENT_LENGTH, response.content().readableBytes());

            if (!keepAlive) {
                ctx.write(response).addListener(ChannelFutureListener.CLOSE);
            } else {
                response.headers().set(CONNECTION, KEEP_ALIVE);
                ctx.write(response);
            }
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }
}

打开浏览器，访问地址：http://192.168.31.153:8080/
浏览器窗口显示Hello world!