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这篇文章主要介绍Netty创建网络服务端客户端示例。
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文章目录
-
- :smirk:1. Netty介绍
- :blush:2. 环境安装与配置
- :satisfied:3. TCP应用示例
- :satisfied:4. UDP应用示例
1. Netty介绍
Netty官网:https://netty.io/
Netty
是一个基于Java的异步事件驱动的网络应用程序框架,专门用于快速开发高性能、可扩展和可维护的网络服务器和客户端。它提供了简单而强大的API,使开发人员能够轻松地构建各种网络应用,包括TCP、UDP、HTTP、WebSocket
等。
以下是一些关键特点和功能:
1.异步和事件驱动:Netty使用非阻塞I/O模型,通过异步事件驱动方式处理网络操作,提供了卓越的性能和可扩展性。
2.高性能:Netty通过有效地利用底层操作系统提供的机制(如选择器、零拷贝等)来实现高效的数据传输和处理,以满足对性能和吞吐量的要求。
3.安全:Netty提供了强大的加密和认证支持,包括SSL/TLS和各种认证机制,保护网络通信的安全性。
4.多协议支持:Netty支持多种主服务器托管网流的网络协议,如TCP、UDP、HTTP、WebSocket等,使开发人员可以方便地构建不同类型的网络应用。
5.灵活的处理程序模型:Netty采用了高度可扩展的处理程序(Handler)模型,使开发人员可以按需配置和组合处理程序来处理网络事件和数据,实现复杂的业务逻辑。
6.内置编解码器:Netty提供了丰富的内置编解码器,使开发人员能够轻松地处理各种协议和数据格式,简化了网络通信中的数据编解码工作。
7.完善的文档和社区支持:Netty拥有完善的官方文档、示例代码和教程,以及活跃的社区支持,使开发人员能够快速上手并解决问题。
2. 环境安装与配置
IDEA创建Netty工程,只要在pom.xml
中引入如下依赖:
dependencies>
dependency>
groupId>io.netty/groupId>
artifactId>netty-all/artifactId>
version>4.1.49.Final/version>
/dependency>
/dependencies>
3. TCP应用示例
创建TCP服务端客户端,需要先开启通道Channel
,然后再有一个事件处理Handler
,下面就创建这4个类:
NettyServer.java
package org.example;
import io.netty.bootstrap.ServerBootstrap;
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.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
public class NettyServer {
private final int port;
public NettyServer(int port) {
this.port = port; // server port
}
public void start() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 128)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializerSocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new NettyServerHandler()); // channel to handler
}
});
ChannelFuture f = b.bind(port).sync();
System.out.println("Server started on port " + port);
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
int port = 8080;
NettyServer server = new NettyServer(port);
server.start();
}
}
NettyServerHandler.java
package org.example;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.util.CharsetUtil;
public class NettyServerHandler extends ChannelInboundHandlerAdapter {
/**
* 读取数据实际(这里我们可以读取客户端发送的消息)
* @param ctx 上下文对象
* @param msg 客户端发送的数据
* @throws Exception
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("server ctx =" + ctx);
Channel channel = ctx.channel();
// 将 msg 转成一个 ByteBuf
// ByteBuf 是 Netty 提供的,不是 NIO 的 ByteBuffer.
ByteBuf buf = (ByteBuf) msg;
System.out.println("客户端发送的消息是: " + buf.toString(CharsetUtil.UTF_8));
System.out.println("客户端地址: " + channel.remoteAddress());
}
/**
* 读取完毕,回复
* @param ctx
* @throws Exception
*/
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
// writeAndFlush 是 write + flush 将数据写入到缓存,并刷新
ctx.writeAndFlush(Unpooled.copiedBuffer("Hello, Client!", CharsetUtil.UTF_8));
}
/**
* 处理异常, 一般是需要关闭通道
* @param ctx
* @param cause
* @throws Exception
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
NettyClient.java
package org.example;
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 NettyClient {
private final String host;
private final int port;
public NettyClient(String host, int port) {
this.host = host; // ip
this.port = port; // port
}
public void start() throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY, true)
.handler(new ChannelInitializerSocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addLast(new NettyClientHandler());
}
});
ChannelFuture f = b.connect(host, port).sync();
System.out.println("Connected to " + host + ":" + port);
f.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
String host = "localhost";
int port = 8080;
NettyClient client = new NettyClient(host, port);
client.start();
}
}
NettyClientHandler.java
package org.example;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;
public class NettyClientHandler extends ChannelInboundHandlerAdapter {
/**
* 通道创建就绪后触发
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("client ctx =" + ctx);
ctx.writeAndFlush(Unpooled.copiedBuffer("Hello, Server!", CharsetUtil.UTF_8));
}
/**
* 当通道有读取事件时,会触发
* @param ctx
* @param msg
* @throws Exception
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
ByteBuf buf = (ByteBuf) msg;
System.out.println("服务器回复的消息:" + buf.toString(CharsetUtil.UTF_8));
System.out.println("服务器的地址: "+ ctx.channel().remoteAddress());
}
/**
* 处理异常, 一般是需要关闭通道
* @param ctx
* @param cause
* @throws Exception
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
}
分别运行服务端和客户端类,结果如下:
4. UDP应用示例
跟上面TCP类似,UDP也是要创建Channel和Handler,下面创建这4个类:
UDPServer.java
package org.example;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.DatagramChannel;
import io.netty.channel.socket.nio.NioDatagramChannel;
public class UDPServer {
private final int port;
public UDPServer(int port) {
this.port = port;
}
public void start() throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioDatagramChannel.class)
.handler(new ChannelInitializerDatagramChannel>() {
@Override
protected void initChannel(DatagramChannel ch) throws Exception {
ch.pipeline().addLast(new UDPServerHandler());
}
});
ChannelFuture f = b.bind(port).sync();
System.out.println("Server started on port " + port);
f.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
int port = 8888;
UDPServer server = new UDPServer(port);
server.start();
}
}
UDPServerHandler.java
package org.example;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.DatagramPacket;
import io.netty.util.CharsetUtil;
public class UDPServerHandler extends SimpleChannelInboundHandlerDatagramPacket> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception {
// 处理接收到的数据
String receivedMessage = msg.content().toString(CharsetUtil.UTF_8);
System.out.println("Received message: " + receivedMessage);
// 响应客户端
String responseMessage = "Hello, client!";
DatagramPacket responsePacket = new DatagramPacket(Unpooled.copiedBuffer(responseMessage, CharsetUtil.UTF_8),
msg.sender());
ctx.writeAndFlush(responsePacket);
}
}
UDPClient.java
package org.example;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.DatagramChannel;
import io.netty.channel.socket.DatagramPacket;
import io.netty.channel.socket.nio.NioDatagramChannel;
import io.netty.util.CharsetUtil;
import java.net.InetSocketAddress;
public class UDPClient {
private final String host;
private final int port;
public UDPClient(String host, int port) {
this.host = host;
this.port = port;
}
public void start() throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioDatagramChannel.class)
.handler(new ChannelInitializerDatagramChannel>() {
@Override
protected void initChannel(DatagramChannel ch) throws Exception {
ch.pipeline().addLast(new UDPClientHandler());
}
});
ChannelFuture f = b.bind(0).sync();
System.out.println("Client started");
// 发送消息给服务端
String message = "Hello, server!";
DatagramPacket packet = new DatagramPacket(Unpooled.copiedBuffer(message, CharsetUtil.UTF_8),
new InetSocketAddress(host, port));
f.channel().writeAndFlush(packet).sync();
f.channel().closeFuture().sync();
} finally {
group.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
String host = "localhost";
int port = 8888;
UDPClient client = new UDPClient(host, port);
client.start();
}
}
UDPClientHandler.java
package org.example;
import io.netty.channel.ChannelHandlerContext;
imp服务器托管网ort io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.socket.DatagramPacket;
import io.netty.util.CharsetUtil;
public class UDPClientHandler extends SimpleChannelInboundHandlerDatagramPacket> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, DatagramPacket msg) throws Exception {
// 处理接收到的数据
String receivedMessage = msg.content().toString(CharsetUtil.UTF_8);
System.out.println("Received response from server: " + receivedMessage);
}
}
运行结果如下:
以上。
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