搭建第一个netty程序
来自action In netty 自己修改一点点
主要依赖
<dependencies> <dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> <version>${netty.version}</version> </dependency> <dependency> <groupId>nia</groupId> <artifactId>utils</artifactId> <version>2.0-SNAPSHOT</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>${junit.version}</version> </dependency> </dependencies> </dependencyManagement> <dependencies> <dependency> <groupId>io.netty</groupId> <artifactId>netty-all</artifactId> </dependency> <dependency> <groupId>nia</groupId> <artifactId>utils</artifactId> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> </dependency> </dependencies>
server端代码
package nia.chapter2.echoserver; import java.net.InetSocketAddress; import io.netty.bootstrap.ServerBootstrap; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; 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.FixedLengthFrameDecoder; /** * 代码清单 2-2 EchoServer 类 * * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a> */ public class EchoServer { private static final byte SPACE = (byte)' '; private final int port; public EchoServer(int port) { this.port = port; } public static void main(String[] args) throws Exception { // if (args.length != 1) { // System.err.println("Usage: " + EchoServer.class.getSimpleName() + // " <port>" // ); // return; // } //设置端口值（如果端口参数的格式不正确，则抛出一个NumberFormatException） int port = Integer.parseInt("8888"); //调用服务器的 start()方法 new EchoServer(port).start(); } public void start() throws Exception { final EchoServerHandler serverHandler = new EchoServerHandler(); //(1) 创建EventLoopGroup EventLoopGroup group = new NioEventLoopGroup(); try { //(2) 创建ServerBootstrap ServerBootstrap b = new ServerBootstrap(); b.group(group) //(3) 指定所使用的 NIO 传输 Channel .channel(NioServerSocketChannel.class) //(4) 使用指定的端口设置套接字地址 .localAddress(new InetSocketAddress(port)) //(5) 添加一个EchoServerHandler到于Channel的 ChannelPipeline .childHandler(new ChannelInitializer<SocketChannel>() { @Override public void initChannel(SocketChannel ch) throws Exception { //EchoServerHandler 被标注为@Shareable，所以我们可以总是使用同样的实例 //这里对于所有的客户端连接来说，都会使用同一个 EchoServerHandler，因为其被标注为@Sharable， //这将在后面的章节中讲到。 //长度编码 ch.pipeline().addLast(new FixedLengthFrameDecoder(32)); ch.pipeline().addLast(serverHandler); } }); //(6) 异步地绑定服务器；调用 sync()方法阻塞等待直到绑定完成 ChannelFuture f = b.bind().sync(); System.out.println(EchoServer.class.getName() + " started and listening for connections on " + f.channel().localAddress()); //(7) 获取 Channel 的CloseFuture，并且阻塞当前线程直到它完成 f.channel().closeFuture().sync(); } finally { //(8) 关闭 EventLoopGroup，释放所有的资源 group.shutdownGracefully().sync(); } } }
对应的serverhandler
package nia.chapter2.echoserver; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandler.Sharable; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelInboundHandlerAdapter; import io.netty.util.CharsetUtil; /** * 代码清单 2-1 EchoServerHandler * * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a> */ //标示一个ChannelHandler可以被多个 Channel 安全地共享 @Sharable public class EchoServerHandler extends ChannelInboundHandlerAdapter { @Override public void channelRead(ChannelHandlerContext ctx, Object msg) { ByteBuf in = (ByteBuf) msg; //将消息记录到控制台 System.out.println( "Server received: " + in.toString(CharsetUtil.UTF_8)); //将接收到的消息写给发送者，而不冲刷出站消息 //ctx.write(in); } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { //将未决消息冲刷到远程节点，并且关闭该 Channel ctx.writeAndFlush(Unpooled.EMPTY_BUFFER) .addListener(ChannelFutureListener.CLOSE); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { //打印异常栈跟踪 cause.printStackTrace(); //关闭该Channel ctx.close(); } }
clien端代码以及handler
package nia.chapter2.echoclient; import io.netty.bootstrap.Bootstrap; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; 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.FixedLengthFrameDecoder; import io.netty.handler.codec.LengthFieldBasedFrameDecoder; import java.net.InetSocketAddress; /** * 代码清单 2-4 客户端的主类 * * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a> */ public class EchoClient { private final String host; private final int port; public EchoClient(String host, int port) { this.host = host; this.port = port; } public void start() throws Exception { EventLoopGroup group = new NioEventLoopGroup(); try { //创建 Bootstrap Bootstrap b = new Bootstrap(); //指定 EventLoopGroup 以处理客户端事件；需要适用于 NIO 的实现 b.group(group) //适用于 NIO 传输的Channel 类型 .channel(NioSocketChannel.class) //设置服务器的InetSocketAddress .remoteAddress(new InetSocketAddress(host, port)) //在创建Channel时，向 ChannelPipeline中添加一个 EchoClientHandler实例 .handler(new ChannelInitializer<SocketChannel>() { @Override public void initChannel(SocketChannel ch) throws Exception { //长度编码 ch.pipeline().addLast( new FixedLengthFrameDecoder(32)); ch.pipeline().addLast( new EchoClientHandler()); } }); //连接到远程节点，阻塞等待直到连接完成 ChannelFuture f = b.connect().sync(); //阻塞，直到Channel 关闭 f.channel().closeFuture().sync(); } finally { //关闭线程池并且释放所有的资源 group.shutdownGracefully().sync(); } } public static void main(String[] args) throws Exception { // if (args.length != 2) { // System.err.println("Usage: " + EchoClient.class.getSimpleName() + // " <host> <port>" // ); // return; // } final String host = "127.0.0.1"; final int port = Integer.parseInt("8888"); new EchoClient(host, port).start(); } }
package nia.chapter2.echoclient; import java.nio.charset.Charset; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelHandler.Sharable; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.util.CharsetUtil; /** * 代码清单 2-3 客户端的 ChannelHandler * * @author <a href="mailto:norman.maurer@gmail.com">Norman Maurer</a> */ @Sharable //标记该类的实例可以被多个 Channel 共享 public class EchoClientHandler extends SimpleChannelInboundHandler<ByteBuf> { @Override public void channelActive(ChannelHandlerContext ctx) { //当被通知 Channel是活跃的时候，发送一条消息 for(int i = 0 ;i<1000;i++) { // ctx.writeAndFlush(Unpooled.copiedBuffer("Netty rocks!", // CharsetUtil.UTF_8)); ctx.writeAndFlush(getByteBuffer(ctx)); } } private ByteBuf getByteBuffer(ChannelHandlerContext ctx) { byte[] bytes = "你好，我的名字是1234567!".getBytes(Charset.forName("utf-8")); ByteBuf buffer = ctx.alloc().buffer(); buffer.writeBytes(bytes); return buffer; } @Override public void channelRead0(ChannelHandlerContext ctx, ByteBuf in) { //记录已接收消息的转储 System.out.println( "Client received: " + in.toString(CharsetUtil.UTF_8)); } @Override //在发生异常时，记录错误并关闭Channel public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { cause.printStackTrace(); ctx.close(); } public static void main(String[] args) { String a = "trumpnoob"; System.out.println(a.length()); System.out.println(a.getBytes().length); } }
这里加了编码器 主要指定了字节长度
判断字节长度使用getbyte.length()
比较简单的处理粘包和粘包的情况
