java网络通信:netty
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。
本文示例采用netty 5.0。上代码.
服务端:
import io.netty.bootstrap.ServerBootstrap;import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
public class TimeServer {
public void bind(int port) throws Exception {
// 配置服务端的NIO,循环事件线程组
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();//配置类
//NioServerSocketChannel作为channel类,它的功能对应于JDK NIO类库中的ServerSocketChannel
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024)
.childHandler(new TimeServerHandler());//绑定事件处理类
// 绑定端口,同步等待成功
ChannelFuture f = b.bind(port).sync();
// 等待服务端监听端口关闭
f.channel().closeFuture().sync();
} finally {
// 优雅退出,释放线程池资源
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
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) {
// 采用默认值
}
}
new TimeServer().bind(port);
}
}
服务端事务处理类:
import io.netty.buffer.ByteBuf;import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
public class TimeServerHandler extends ChannelHandlerAdapter {
/*当有数据时,自动调用,读取msg*/
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);
}
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
ctx.close();
}
}
客户端:
import io.netty.bootstrap.Bootstrap;import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
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>() {
//ChannelInitializer<SocketChannel>匿名类初始化channel的pipeline,将客户端事务处理类加入到队列中@Override
public void initChannel(SocketChannel ch)
throws Exception {
ch.pipeline().addLast(new TimeClientHandler());
}
});
// 发起异步连接操作
ChannelFuture f = b.connect(host, port).sync();
// 当代客户端链路关闭
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) {
// 采用默认值
}
}
new TimeClient().connect(port, "127.0.0.1");
}
}
客户端事件处理类:
import io.netty.buffer.ByteBuf;import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import java.util.logging.Logger;
public class TimeClientHandler extends ChannelHandlerAdapter {
private static final Logger logger = Logger
.getLogger(TimeClientHandler.class.getName());
private final ByteBuf firstMessage;
public TimeClientHandler() {
byte[] req = "QUERY TIME ORDER".getBytes();
firstMessage = Unpooled.buffer(req.length);
firstMessage.writeBytes(req);
}
/*连接成功后,自动发送消息*/
public void channelActive(ChannelHandlerContext ctx) {
ctx.writeAndFlush(firstMessage);
}
/*有消息返回时,自动调用该函数读取*/
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);
}
/*发生异常时,自动调用*/
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
// 释放资源
logger.warning("Unexpected exception from downstream : "
+ cause.getMessage());
ctx.close();
}
}
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