第三章 Netty入门
3.1所需jar包
导入netty-all-5.0.0.Alpha1.jar 的包。
3.2 服务端代码
public class TimeServer {
public void bind(int port) throws Exception{
//NioEventLoopGroup表示线程组
EventLoopGroup bossGroup = new NioEventLoopGroup();//服务端接受客户端的连接
EventLoopGroup workerGroup = new NioEventLoopGroup();//进行SocketChannel的网络读写
try {
//ServerBootstrap用于启动NIO服务端的辅助启动类
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup) //将两个NIO线程组当作入参传递到ServerBootstrap对象
.channel(NioServerSocketChannel.class) //设置Channel为NioServerSocketChannel
.option(ChannelOption.SO_BACKLOG, 1024) //配置TCP的backlog为1024
.childHandler(new ChildChannelHander()); //绑定ChildChannelHander
//绑定端口,同步等待成功
ChannelFuture f = b.bind(port).sync();
//等待服务器监听端口关闭
f.channel().closeFuture().sync();
} finally{
//优雅退出,释放线程池资源
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
private class ChildChannelHander extends ChannelInitializer<SocketChannel>{
@Override
protected void initChannel(SocketChannel arg0) throws Exception {
arg0.pipeline().addLast(new TimeServerHandler());
}
}
public static void main(String[] args) throws Exception {
int port = 8080;
if(args!=null && args.length>0){
try{
port = Integer.valueOf(args[0]);
}catch(NumberFormatException e){
}
}
new TimeServer().bind(port);
}
}
public class TimeServerHandler extends ChannelHandlerAdapter {
//用于网络事件进行读写操作,通常只关注channelRead和exceptionCaught方法
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
ByteBuf buf = (ByteBuf) msg;
byte[] req = new byte[buf.readableBytes()];
buf.readBytes(req);
String body = new String(req, "UTF-8");
System.out.println("The time server receive order : " + body);
String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new java.util.Date(
System.currentTimeMillis()).toString() : "BAD ORDER";
ByteBuf resp = Unpooled.copiedBuffer(currentTime.getBytes());
ctx.write(resp);//发送消息给客户端
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
ctx.close();
}
}
3.3 客户端代码
public class TimeClient {
public void connect(int port,String host) throws Exception{
//配置客户端NIO线程组
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 {
ch.pipeline().addLast(new TimeClientHandler());
}
});
//发起异步连续操作
ChannelFuture f = b.connect(host, port).sync();
//等待客户端链路关闭
f.channel().closeFuture().sync();
} finally{
//优雅退出,释放NIO线程组
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
int port = 8080;
if(args!=null && args.length>0){
try {
port = Integer.valueOf(args[0]);
} catch (NumberFormatException e) {
// TODO: handle exception
}
}
new TimeClient().connect(port, "127.0.0.1");
}
}
TimeClientHandler类
public class TimeClientHandler extends ChannelHandlerAdapter {
private static final Logger logger = Logger
.getLogger(TimeClientHandler.class.getName());
private final ByteBuf firstMessage;
/**
* Creates a client-side handler.
*/
public TimeClientHandler() {
byte[] req = "QUERY TIME ORDER".getBytes();
firstMessage = Unpooled.buffer(req.length);
firstMessage.writeBytes(req);
}
//客户端和服务器TCP链路建立成功之后
@Override
public void channelActive(ChannelHandlerContext ctx) {
ctx.writeAndFlush(firstMessage);
}
//服务端返回消息时被调用
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
ByteBuf buf = (ByteBuf) msg;
byte[] req = new byte[buf.readableBytes()];
buf.readBytes(req);
String body = new String(req, "UTF-8");
System.out.println("Now is : " + body);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
// 释放资源
logger.warning("Unexpected exception from downstream : "
+ cause.getMessage());
ctx.close();
}
}