Netty是由JBOSS提供的一个java开源框架。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。
也就是说，Netty 是一个基于NIO的客户，服务器端编程框架，使用Netty 可以确保你快速和简单的开发出一个网络应用，例如实现了某种协议的客户，服务端应用。Netty相当简化和流线化了网络应用的编程开发过程，例如，TCP和UDP的socket服务开发。
“快速”和“简单”并不意味着会让你的最终应用产生维护性或性能上的问题。Netty 是一个吸收了多种协议的实现经验，这些协议包括FTP,SMTP,HTTP，各种二进制，文本协议，并经过相当精心设计的项目，最终，Netty 成功的找到了一种方式，在保证易于开发的同时还保证了其应用的性能，稳定性和伸缩性。
一、maven信息：
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.5.Final</version>
</dependency>
二、示例：
Netty是网络应用程序框架和工具，接下来我们以C/S的模式来展示Netty的编程过程。
Client：
public class Client {
static final String HOST = System.getProperty("host", "127.0.0.1");
static final int PORT = Integer.parseInt(System.getProperty("port", "8080"));
static final int SIZE = Integer.parseInt(System.getProperty("size", "256"));
public static void main(String[] args) throws Exception {
// 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();
p.addLast("decoder", new StringDecoder());
p.addLast("encoder", new StringEncoder());
p.addLast(new ClientHandler());
}
});
ChannelFuture future = b.connect(HOST, PORT).sync();
future.channel().writeAndFlush("Hello Netty Server ,I am a common client");
future.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
}
Client实际操作：
public class ClientHandler extends ChannelInboundHandlerAdapter{
@Override
public void channelActive(ChannelHandlerContext ctx) {
System.out.println("HelloWorldClientHandler Active");
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
System.out.println("HelloWorldClientHandler read Message:"+msg);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
cause.printStackTrace();
ctx.close();
}
}
Server：
public class Server {
private int port;
public Server(int port){
this.port = port;
}
public void start(){
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap serverBootstrap = new ServerBootstrap().group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
.localAddress(port).childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast("decoder", new StringDecoder());
ch.pipeline().addLast("encoder", new StringEncoder());
ch.pipeline().addLast(new ServerHandler());
}
}).option(ChannelOption.SO_BACKLOG, 128)
.childOption(ChannelOption.SO_KEEPALIVE, true);
ChannelFuture future = serverBootstrap.bind(port).sync();
System.out.println("Server start listen at " + port );
future.channel().closeFuture().sync();
} catch (Exception e) {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
int port;
if (args.length > 0) {
port = Integer.parseInt(args[0]);
} else {
port = 8080;
}
new Server(port).start();
}
}
Server实际操作
public class ServerHandler extends ChannelInboundHandlerAdapter{
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("server channelRead..");
System.out.println(ctx.channel().remoteAddress()+"->Server :"+ msg.toString());
ctx.write("server write"+msg);
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
Client运行结果：
Server运行结果：
