Java NIO框架--Netty4的简单示例

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摘要: Java NIO框架--Netty4的简单示例

简介

相比Netty3, Netty4有很多显著的变化：

NioEventLoopGroup 是一个处理I/O操作的多线程事件环。即为Netty4里的线程池，在3.x里，一个Channel是由ChannelFactory创建的，同时新创建的Channel会自动注册到一个隐藏的I/O线程。 4.0使用新的名为EventLoopGroup的接口来替换ChannelFactory，它由一个或多个EventLoop来构成。一个新的 Channel不会自动注册到EventLoopGroup，但用户可以显式调用EventLoopGroup.register（）来注册。在Server端的Bootstrap参数中，有两个EventLoopGroup，第一个通常称为'boss'，用于接收发来的连接请求。第二个称为'worker',，用于处理boss接受并且注册给worker的连接中的信息。

ChannelInitializer是一个特殊的handler，用于方便的配置用户自定义的handler实现，如代码中所示。在channelRegistered的生命周期中会触发用户复写的initChannel(C ch)方法，并且在调用后会讲自身从channelPipeline中移除。

代码示例

import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelOption;import io.netty.channel.ChannelPipeline;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioServerSocketChannel;import io.netty.handler.codec.serialization.ClassResolvers;import io.netty.handler.codec.serialization.ObjectDecoder;import io.netty.handler.codec.serialization.ObjectEncoder;import io.netty.handler.logging.LogLevel;import io.netty.handler.logging.LoggingHandler;import io.netty.handler.ssl.SslContext;import io.netty.handler.ssl.util.SelfSignedCertificate;/** * DateTime: 2015年1月5日 上午9:56:10 * */public class HelloWorldServer {    static final boolean SSL = System.getProperty("ssl") != null;    static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));    public static void main(String[] args) throws Exception {        // Configure SSL.        final SslContext sslCtx;        if (SSL) {            SelfSignedCertificate ssc = new SelfSignedCertificate();            sslCtx = SslContext.newServerContext(ssc.certificate(), ssc.privateKey());        } else {            sslCtx = null;        }        // Configure the server.        EventLoopGroup bossGroup = new NioEventLoopGroup(1);        EventLoopGroup workerGroup = new NioEventLoopGroup();        try {            ServerBootstrap b = new ServerBootstrap();            b.group(bossGroup, workerGroup)             .channel(NioServerSocketChannel.class)             .option(ChannelOption.SO_BACKLOG, 100)             .handler(new LoggingHandler(LogLevel.INFO))             .childHandler(new ChannelInitializer<SocketChannel>() {                 @Override                 public void initChannel(SocketChannel ch) throws Exception {                     ChannelPipeline p = ch.pipeline();                     if (sslCtx != null) {                         p.addLast(sslCtx.newHandler(ch.alloc()));                     }                     p.addLast(new LoggingHandler(LogLevel.INFO));                     p.addLast(                         new ObjectEncoder(),                         new ObjectDecoder(ClassResolvers.cacheDisabled(null)),                         new HelloWorldServerHandler());                 }             });            // Start the server.            ChannelFuture f = b.bind(PORT).sync();            // Wait until the server socket is closed.            f.channel().closeFuture().sync();        } finally {            // Shut down all event loops to terminate all threads.            bossGroup.shutdownGracefully();            workerGroup.shutdownGracefully();        }    }}class HelloWorldServerHandler extends ChannelInboundHandlerAdapter {    @Override    public void channelRead(ChannelHandlerContext ctx, Object msg) {        ctx.write("server write msg:"+msg);    }    @Override    public void channelReadComplete(ChannelHandlerContext ctx) {        ctx.flush();    }    @Override    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {        // Close the connection when an exception is raised.        cause.printStackTrace();        ctx.close();    }}

import io.netty.bootstrap.Bootstrap;import io.netty.channel.ChannelFuture;import io.netty.channel.ChannelHandlerContext;import io.netty.channel.ChannelInboundHandlerAdapter;import io.netty.channel.ChannelInitializer;import io.netty.channel.ChannelOption;import io.netty.channel.ChannelPipeline;import io.netty.channel.EventLoopGroup;import io.netty.channel.nio.NioEventLoopGroup;import io.netty.channel.socket.SocketChannel;import io.netty.channel.socket.nio.NioSocketChannel;import io.netty.handler.codec.serialization.ClassResolvers;import io.netty.handler.codec.serialization.ObjectDecoder;import io.netty.handler.codec.serialization.ObjectEncoder;import io.netty.handler.ssl.SslContext;import io.netty.handler.ssl.util.InsecureTrustManagerFactory;/** * DateTime: 2015年1月5日 上午9:56:22 * */public class HelloWorldClient {    static final boolean SSL = System.getProperty("ssl") != null;    static final String HOST = System.getProperty("host", "127.0.0.1");    static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));    public static void main(String[] args) throws Exception {        // Configure SSL.git        final SslContext sslCtx;        if (SSL) {            sslCtx = SslContext.newClientContext(InsecureTrustManagerFactory.INSTANCE);        }        else {            sslCtx = null;        }        // Configure the client.        EventLoopGroup group = new NioEventLoopGroup();        try {            Bootstrap b = new Bootstrap();            b.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)                .handler(new ChannelInitializer<SocketChannel>() {                    @Override                    public void initChannel(SocketChannel ch) throws Exception {                        ChannelPipeline p = ch.pipeline();                        if (sslCtx != null) {                            p.addLast(sslCtx.newHandler(ch.alloc(), HOST, PORT));                        }                        p.addLast(new ObjectEncoder(), new ObjectDecoder(ClassResolvers.cacheDisabled(null)),                            new HelloWorldClientHandler());                    }                });            // Start the client.            ChannelFuture f = b.connect(HOST, PORT).sync();            // Wait until the connection is closed.            f.channel().closeFuture().sync();        }        finally {            // Shut down the event loop to terminate all threads.            group.shutdownGracefully();        }    }}class HelloWorldClientHandler extends ChannelInboundHandlerAdapter {    private final String msg = "hello java world";    /**     * Creates a client-side handler.     */    public HelloWorldClientHandler() {        //TODO    }    @Override    public void channelActive(ChannelHandlerContext ctx) {        ctx.writeAndFlush(msg);    }    @Override    public void channelRead(ChannelHandlerContext ctx, Object msg) {        System.out.println(msg);        //        ctx.write(msg);    }    @Override    public void channelReadComplete(ChannelHandlerContext ctx) {        ctx.flush();    }    @Override    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {        // Close the connection when an exception is raised.        cause.printStackTrace();        ctx.close();    }}

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