1.使用 SSL/TLS 创建安全的 Netty 程序
SSL 和 TLS 是众所周知的标准和分层的协议，它们可以确保数据时私有的
Netty提供了SSLHandler对网络数据进行加密
使用Https
public class SslChannelInitialzer extends ChannelInitializer<Channel>{ ???private final SSLContext context; ???private final boolean client; ???private final boolean startTls; ???public SslChannelInitialzer(SSLContext context, boolean client, boolean startTls) { ???????this.context = context; ???????this.client = client; ???????this.startTls = startTls; ???} ???@Override ???protected void initChannel(Channel ch) throws Exception { ???????SSLEngine engine = context.createSSLEngine(); ???????engine.setUseClientMode(client); ???????ch.pipeline().addFirst("ssl", new SslHandler(engine, startTls)); ???}}2.使用 Netty 创建 HTTP/HTTPS 程序
public class HttpDecoderEncodeIntializer extends ChannelInitializer<Channel>{ ???private final boolean client; ???????public HttpDecoderEncodeIntializer(boolean client) { ???????this.client = client; ???} ???@Override ???protected void initChannel(Channel ch) throws Exception { ???????ChannelPipeline pipeline = ch.pipeline(); ???????????????if (client) { ???????????pipeline.addLast("decoder", new HttpResponseDecoder()); ???????????pipeline.addLast("", new HttpRequestEncoder());
pipeline.addLast("decompressor", new HttpContentDecompressor()); //添加解压缩 Handler ???????} else { ???????????pipeline.addLast("decoder", new HttpRequestEncoder()); ???????????pipeline.addLast("encoder", new HttpResponseDecoder()); ???????} ???}}如果你需要在 ChannelPipeline 中有一个解码器和编码器，还分别有一个在客户端和服务器简单的编解码器：HttpClientCodec 和 HttpServerCodec
pipeline.addLast("aggegator", new HttpObjectAggregator(512 * 1024)); 聚合消息
WebSocket
WebSocketServerProtocolHandler
处理空闲连接和超时
- IdleStateHandler，当一个通道没有进行读写或运行了一段时间后出发IdleStateEvent
- ReadTimeoutHandler，在指定时间内没有接收到任何数据将抛出ReadTimeoutException
- WriteTimeoutHandler，在指定时间内有写入数据将抛出WriteTimeoutException、
最常用的是IdleStateHandler，下面代码显示了如何使用IdleStateHandler，如果60秒内没有接收数据或发送数据，操作将失败，连接将关闭
public class IdleStateHandlerInitializer extends ChannelInitializer<Channel> { ????@Override ???protected void initChannel(Channel ch) throws Exception { ???????ChannelPipeline pipeline = ch.pipeline(); ???????pipeline.addLast(new IdleStateHandler(0, 0, 60, TimeUnit.SECONDS)); ???????pipeline.addLast(new HeartbeatHandler()); ???} ????public static final class HeartbeatHandler extends ChannelInboundHandlerAdapter { ???????private static final ByteBuf HEARTBEAT_SEQUENCE = Unpooled.unreleasableBuffer(Unpooled.copiedBuffer( ???????????????"HEARTBEAT", CharsetUtil.UTF_8)); ????????@Override ???????public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception { ???????????if (evt instanceof IdleStateEvent) { ???????????????ctx.writeAndFlush(HEARTBEAT_SEQUENCE.duplicate()).addListener(ChannelFutureListener.CLOSE_ON_FAILURE); ???????????} else { ???????????????super.userEventTriggered(ctx, evt); ???????????} ???????} ???}}分隔符协议 解决粘包问题
使用LineBasedFrameDecoder提取"\r\n"分隔帧
/** * 处理换行分隔符消息 * */public class LineBasedHandlerInitializer extends ChannelInitializer<Channel> { ????@Override ???protected void initChannel(Channel ch) throws Exception { ???????ch.pipeline().addLast(new LineBasedFrameDecoder(65 * 1204), new FrameHandler()); ???} ????public static final class FrameHandler extends SimpleChannelInboundHandler<ByteBuf> { ???????@Override ???????protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) throws Exception { ???????????// do something with the frame ???????} ???}}如果框架的东西除了换行符还有别的分隔符，可以使用DelimiterBasedFrameDecoder，只需要将分隔符传递到构造方法中。如果想实现自己的以分隔符为基础的协议，这些解码器是有用的。
例如，现在有个协议，它只处理命令，这些命令由名称和参数形成，名称和参数由一个空格分隔
public class CmdHandlerInitializer extends ChannelInitializer<Channel> { ????@Override ???protected void initChannel(Channel ch) throws Exception { ???????ch.pipeline().addLast(new CmdDecoder(65 * 1024), new CmdHandler()); ???} ????public static final class Cmd { ???????private final ByteBuf name; ???????private final ByteBuf args; ????????public Cmd(ByteBuf name, ByteBuf args) { ???????????this.name = name; ???????????this.args = args; ???????} ????????public ByteBuf getName() { ???????????return name; ???????} ????????public ByteBuf getArgs() { ???????????return args; ???????} ???} ????public static final class CmdDecoder extends LineBasedFrameDecoder { ????????public CmdDecoder(int maxLength) { ???????????super(maxLength); ???????} ????????@Override ???????protected Object decode(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception { ???????????ByteBuf frame = (ByteBuf) super.decode(ctx, buffer); ???????????if (frame == null) { ???????????????return null; ???????????} ???????????int index = frame.indexOf(frame.readerIndex(), frame.writerIndex(), (byte) ‘ ‘); ???????????return new Cmd(frame.slice(frame.readerIndex(), index), frame.slice(index + 1, frame.writerIndex())); ???????} ???} ????public static final class CmdHandler extends SimpleChannelInboundHandler<Cmd> { ???????@Override ???????protected void channelRead0(ChannelHandlerContext ctx, Cmd msg) throws Exception { ???????????// do something with the command ???????} ???} }一般经常会碰到以长度为基础的协议，对于这种情况Netty有两个不同的解码器可以帮助我们来解码：
- FixedLengthFrameDecoder
- LengthFieldBasedFrameDecoder
ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(65*1024, 0, 8))
读取大文件
@Override ???public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { ???????File file = new File("test.txt"); ???????FileInputStream fis = new FileInputStream(file); ???????FileRegion region = new DefaultFileRegion(fis.getChannel(), 0, file.length()); ???????Channel channel = ctx.channel(); ???????channel.writeAndFlush(region).addListener(new ChannelFutureListener() { ???????????????????????@Override ???????????public void operationComplete(ChannelFuture future) throws Exception { ???????????????if(!future.isSuccess()){ ???????????????????Throwable cause = future.cause(); ???????????????????// do something ???????????????} ???????????} ???????}); ???}public class ChunkedWriteHandlerInitializer extends ChannelInitializer<Channel> { ???private final File file; ????public ChunkedWriteHandlerInitializer(File file) { ???????this.file = file; ???} ????@Override ???protected void initChannel(Channel ch) throws Exception { ???????ch.pipeline().addLast(new ChunkedWriteHandler()) ???????????.addLast(new WriteStreamHandler()); ???} ????public final class WriteStreamHandler extends ChannelInboundHandlerAdapter { ???????@Override ???????public void channelActive(ChannelHandlerContext ctx) throws Exception { ???????????super.channelActive(ctx); ???????????ctx.writeAndFlush(new ChunkedStream(new FileInputStream(file))); ???????} ???}}通过JBoss编组序列化
使用ProtoBuf序列化
/** * 使用protobuf序列化数据，进行编码解码 * 注意：使用protobuf需要protobuf-java-2.5.0.jar * @author Administrator * */public class ProtoBufInitializer extends ChannelInitializer<Channel> { ????private final MessageLite lite; ????public ProtoBufInitializer(MessageLite lite) { ???????this.lite = lite; ???} ????@Override ???protected void initChannel(Channel ch) throws Exception { ???????ch.pipeline().addLast(new ProtobufVarint32FrameDecoder()) ???????????.addLast(new ProtobufEncoder()) ???????????.addLast(new ProtobufDecoder(lite)) ???????????.addLast(new ObjectHandler()); ???} ????public final class ObjectHandler extends SimpleChannelInboundHandler<Serializable> { ???????@Override ???????protected void channelRead0(ChannelHandlerContext ctx, Serializable msg) throws Exception { ???????????// do something ???????} ???}}Bootstrap 当需要引导客户端或一些无连接协议时
创建Bootstrap实例使用new关键字，下面是Bootstrap的方法：
- group(...)，设置EventLoopGroup,EventLoopGroup用来处理所有通道的IO事件
- channel(...)，设置通道类型
- channelFactory(...)，使用ChannelFactory来设置通道类型
- localAddress(...)，设置本地地址，也可以通过bind(...)或connect(...)
- option(ChannelOption<T>, T)，设置通道选项，若使用null，则删除上一个设置的ChannelOption
- attr(AttributeKey<T>, T)，设置属性到Channel，若值为null，则指定键的属性被删除
- handler(ChannelHandler)，设置ChannelHandler用于处理请求事件
- clone()，深度复制Bootstrap，Bootstrap的配置相同
- remoteAddress(...)，设置连接地址
- connect(...)，连接远程通道
- bind(...)，创建一个新的Channel并绑
ServerBootstrap 引导服务器
从Channel引导客户端
有时候需要从另一个Channel引导客户端，例如写一个代理或需要从其他系统检索数据。从其他系统获取数据时比较常见的，有很多Netty应用程序必须要和企业现有的系统集成，如Netty程序与内部系统进行身份验证，查询数据库等
可以不用再创建新的引导
public class BootstrapingFromChannel { ???????public static void main(String[] args) throws Exception { ???????EventLoopGroup bossGroup = new NioEventLoopGroup(1); ???????EventLoopGroup workerGroup = new NioEventLoopGroup(); ???????ServerBootstrap b = new ServerBootstrap(); ???????b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class) ???????????????.childHandler(new SimpleChannelInboundHandler<ByteBuf>() { ???????????????????ChannelFuture connectFuture; ????????????????????@Override ???????????????????public void channelActive(ChannelHandlerContext ctx) throws Exception { ???????????????????????Bootstrap b = new Bootstrap(); ???????????????????????b.channel(NioSocketChannel.class).handler( ???????????????????????????????new SimpleChannelInboundHandler<ByteBuf>() { ???????????????????????????????????@Override ???????????????????????????????????protected void channelRead0(ChannelHandlerContext ctx, ???????????????????????????????????????????ByteBuf msg) throws Exception { ???????????????????????????????????????System.out.println("Received data"); ???????????????????????????????????????msg.clear(); ???????????????????????????????????} ???????????????????????????????}); ???????????????????????b.group(ctx.channel().eventLoop()); ???????????????????????connectFuture = b.connect(new InetSocketAddress("127.0.0.1", 2048)); ???????????????????} ????????????????????@Override ???????????????????protected void channelRead0(ChannelHandlerContext ctx, ByteBuf msg) ???????????????????????????throws Exception { ???????????????????????if (connectFuture.isDone()) { ???????????????????????????// do something with the data ???????????????????????} ???????????????????} ???????????????}); ???????ChannelFuture f = b.bind(2048); ???????f.addListener(new ChannelFutureListener() { ???????????@Override ???????????public void operationComplete(ChannelFuture future) throws Exception { ???????????????if (future.isSuccess()) { ???????????????????System.out.println("Server bound"); ???????????????} else { ???????????????????System.err.println("bound fail"); ???????????????????future.cause().printStackTrace(); ???????????????} ???????????} ???????}); ???}}使用通道选项和属性
使用ChannelOption和属性可以让事情变得很简单，例如Netty WebSocket服务器根据用户自动路由消息，通过使用属性，应用程序能在通道存储用户ID以确定消息应该发送到哪里。应用程序可以通过使用一个通道选项进一步自动化，给定时间内没有收到消息将自动断开连接
???public static void main(String[] args) { ???????//创建属性键对象 ???????final AttributeKey<Integer> id = AttributeKey.valueOf("ID"); ???????//客户端引导对象 ???????Bootstrap b = new Bootstrap(); ???????//设置EventLoop，设置通道类型 ???????b.group(new NioEventLoopGroup()).channel(NioSocketChannel.class) ???????//设置ChannelHandler ???????????.handler(new SimpleChannelInboundHandler<ByteBuf>() { ???????????????????@Override ???????????????public void channelRegistered(ChannelHandlerContext ctx) throws Exception { ???????????????????//通道注册后执行，获取属性值 ???????????????????Integer idValue = ctx.channel().attr(id).get(); ???????????????????System.out.println(idValue); ???????????????????//do something with the idValue ???????????????} ???????????????@Override ???????????????protected void messageReceived(ChannelHandlerContext ctx, ByteBuf msg) throws Exception { ???????????????????System.out.println("Reveived data"); ???????????????????msg.clear(); ???????????????} ???????????}); ???????//设置通道选项，在通道注册后或被创建后设置 ???????b.option(ChannelOption.SO_KEEPALIVE, true).option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 5000); ???????//设置通道属性 ???????b.attr(id, 123456); ???????ChannelFuture f = b.connect("www.manning.com",80); ???????f.syncUninterruptibly(); ???}创建安全的 Netty 程序
原文地址：https://www.cnblogs.com/mxz1994/p/9464309.html