Netty成长之路——初始Netty
前言
初始Netty框架是在一家电商公司，开发微信应用小程序，解决客服聊天系统消息使用方案时用到的。在此之前，也仅仅是了解过它，写过一些demo而已，从未深入学习过。这次因为研发的产品需要，有幸再次学习它，索性我就搞个透。言规正传，我们这就开始。
1、Netty简介
Netty 是一个基于NIO的客户端、服务端的编程框架，使用Netty可以确保你快速和简单的开发出一个网络应用，Netty相当于简化和流线化了网络应用的编程开发过程，Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。它的体系结构图如下：
2、Netty特性
设计
各种传输类型的统一API——阻塞和非阻塞套接字 基于灵活和可扩展的事件模型，允许明确的关注点分离 高度可定制的线程模型——单个线程，一个或多个线程池，如SEDA 真正的无连接数据报套接字支持(从3.1开始)易用性
文档良好的Javadoc、用户指南和示例 没有额外的依赖，JDK 5 (Netty 3.x)或6 (Netty 4.x)就足够了性能
更好的吞吐量，更低的延迟 减少资源消耗 最小化不必要的内存拷贝安全
支持SSL/TLS和StartTLS 3、Netty示例代码下面主要使用示例，演示Netty客户端和服务端使用效果。
Netty服务端
public class NettyServer {
/**
* boss 线程组用于处理连接工作
*/
private EventLoopGroup bossGroup = new NioEventLoopGroup();
/**
* work 线程组用于数据处理
*/
private EventLoopGroup workerGroup = new NioEventLoopGroup();
@Value("${nettyServer.port}")
private int port;
/*public NettyServer(int port) {
this.port = port;
}*/
@PostConstruct
public void run() throws Exception {
ServerBootstrap b = new ServerBootstrap(); // (2)
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class) // (3)
.childHandler(new NettyServerInitializer()) //(4)
.option(ChannelOption.SO_BACKLOG, 128) // (5)
.childOption(ChannelOption.SO_KEEPALIVE, true); // (6)
// 绑定端口，开始接收进来的连接
ChannelFuture f = b.bind(port).sync();
if (f.isSuccess()) {
log.info("启动 Netty Server");
}
//f.channel().closeFuture().sync();
}
@PreDestroy
public void destory() throws InterruptedException {
bossGroup.shutdownGracefully().sync();
workerGroup.shutdownGracefully().sync();
log.info("关闭Netty");
}
NettyServerHandler.java
public class NettyServerHandler extends SimpleChannelInboundHandler {
/**
* A thread-safe Set Using ChannelGroup, you can categorize Channels into a meaningful group.
* A closed Channel is automatically removed from the collection,
*/
public static ChannelGroup channels = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
Channel incoming = ctx.channel();
// Broadcast a message to multiple Channels
channels.writeAndFlush("[SERVER] - " + incoming.remoteAddress() + " 加入\n");
channels.add(ctx.channel());
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
Channel incoming = ctx.channel();
// Broadcast a message to multiple Channels
channels.writeAndFlush("[SERVER] - " + incoming.remoteAddress() + " 离开\n");
// A closed Channel is automatically removed from ChannelGroup,
// so there is no need to do "channels.remove(ctx.channel());"
}
@Override
protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {
log.info("接收到客户端消息：{}", s);
try{
if (!StringUtils.isEmpty(s)) {
PushNettyData jsonMsg = GsonUtils.fromJson(s, PushNettyData.class);
if ("new-sample".equals(jsonMsg.getMsgType())) {
log.info("样本编号：{}",jsonMsg.getSampleNo());
//保存ctx对象
NettyDataComponent nettyDataComponent = new NettyDataComponent();
nettyDataComponent.addNettyDataMap(jsonMsg.getSampleNo(), ctx);
}
}
}finally {
ReferenceCountUtil.release(s);
}
/* Channel incoming = ctx.channel();
for (Channel channel : channels) {
if (channel != incoming) {
channel.writeAndFlush("[" + incoming.remoteAddress() + "]" + s + "\n");
} else {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
while (true) {
channel.writeAndFlush("[server]" + in.readLine() + "\r\n");
}
}
}*/
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
Channel incoming = ctx.channel();
log.info("NettyClient:" + incoming.remoteAddress() + "在线");
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
Channel incoming = ctx.channel();
log.info("NettyClient:" + incoming.remoteAddress() + "掉线");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
Channel incoming = ctx.channel();
log.info("NettyClient:" + incoming.remoteAddress() + "异常");
// 当出现异常就关闭连接
cause.printStackTrace();
ctx.close();
}
}
NettyServerInitializer.java
public class NettyServerInitializer extends ChannelInitializer {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("handler", new NettyServerHandler());
log.info("NettyClient:" + ch.remoteAddress() + "连接上");
}
}
Netty客户端
public class NettyClient {
public static void main(String[] args) throws Exception {
//new NettyClient("localhost", 8087).run();
String stitchUrl = "http://127.0.0.1:8088/img/stitch/thumb-AB0003-000011.png";
stitchUrl = stitchUrl.replace("//", "/");
System.out.println(stitchUrl);
}
private final String host;
private final int port;
public NettyClient(String host, int port) {
this.host = host;
this.port = port;
}
public void run() throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap()
.group(group)
.channel(NioSocketChannel.class)
.handler(new NettyClientInitializer());
Channel channel = bootstrap.connect(host, port).sync().channel();
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
while (true) {
channel.writeAndFlush("[client]" + in.readLine() + "\r\n");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
group.shutdownGracefully();
}
}
}
NettyClientHandler.java
public class NettyClientHandler extends SimpleChannelInboundHandler {
@Override
protected void channelRead0(ChannelHandlerContext ctx, String s) throws Exception {
System.out.println("客户端消息："+s);
}
}
NettyClientInitializer.java
public class NettyClientInitializer extends ChannelInitializer {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast("framer", new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter()));
pipeline.addLast("decoder", new StringDecoder());
pipeline.addLast("encoder", new StringEncoder());
pipeline.addLast("handler", new NettyClientHandler());
}
}
后续文章将对Netty框架各个模块进行详细分析等。敬请期待！
快马扬鞭
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