关于Netty
Netty 是一个利用 Java 的高级网络的能力，隐藏其背后的复杂性而提供一个易于使用的 API 的客户端/服务器框架。
MAVEN依赖
<!-- websocket -->
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.36.Final</version>
</dependency>
<!--添加static和templates的依赖/html-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
创建启动器
启动器中需要new一个NettyServer，并显式调用启动netty
package com.mqtt;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import com.mqtt.demo3.NettyServer;
@SpringBootApplication
public class MqttdemoApplication {
public static void main(String[] args) {
SpringApplication.run(MqttdemoApplication.class, args);
try {
System.out.println("http://127.0.0.1:8888/ws/index");
new NettyServer(12345).start();
} catch (Exception e) {
System.out.println("NettyServerError:" + e.getMessage());
}
}
}
NettyServer
package com.mqtt.demo3;
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.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.stream.ChunkedWriteHandler;
public class NettyServer {
private final int port;
public NettyServer(int port) {
this.port = port;
}
public void start() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup group = new NioEventLoopGroup();
try {
ServerBootstrap sb = new ServerBootstrap();
sb.option(ChannelOption.SO_BACKLOG, 1024);
sb.group(group, bossGroup) // 绑定线程池
.channel(NioServerSocketChannel.class) // 指定使用的channel
.localAddress(this.port)// 绑定监听端口
.childHandler(new ChannelInitializer<SocketChannel>() { // 绑定客户端连接时候触发操作
@Override
protected void initChannel(SocketChannel ch) throws Exception {
System.out.println("收到新连接");
//websocket协议本身是基于http协议的，所以这边也要使用http解编码器
ch.pipeline().addLast(new HttpServerCodec());
//以块的方式来写的处理器
ch.pipeline().addLast(new ChunkedWriteHandler());
ch.pipeline().addLast(new HttpObjectAggregator(8192));
ch.pipeline().addLast(new WebSocketServerProtocolHandler("/ws", "WebSocket", true, 65536 * 10));
ch.pipeline().addLast(new MyWebSocketHandler());
}
});
ChannelFuture cf = sb.bind().sync(); // 服务器异步创建绑定
System.out.println(NettyServer.class + " 启动正在监听： " + cf.channel().localAddress());
cf.channel().closeFuture().sync(); // 关闭服务器通道
} finally {
group.shutdownGracefully().sync(); // 释放线程池资源
bossGroup.shutdownGracefully().sync();
}
}
}
MyChannelHandlerPool
通道组池，管理所有websocket连接
package com.mqtt.demo3;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;
public class MyChannelHandlerPool {
public MyChannelHandlerPool(){}
public static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
}
MyWebSocketHandler
处理ws一下几种情况：
channelActive与客户端建立连接
channelInactive与客户端断开连接
channelRead0客户端发送消息处理
MyWebSocketHandler
package com.mqtt.demo3;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
public class MyWebSocketHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("与客户端建立连接，通道开启！");
//添加到channelGroup通道组
MyChannelHandlerPool.channelGroup.add(ctx.channel());
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println("与客户端断开连接，通道关闭！");
//添加到channelGroup 通道组
MyChannelHandlerPool.channelGroup.remove(ctx.channel());
}
@Override
protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
System.out.println("客户端收到服务器数据：" + msg.text());
sendAllMessage(msg.text());
}
private void sendAllMessage(String message){
//收到信息后，群发给所有channel
MyChannelHandlerPool.channelGroup.writeAndFlush( new TextWebSocketFrame(message));
}
}
socket.html
保存在 %/resources/static目录下
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Netty-Websocket</title>
<script type="text/javascript">
// by zhengkai.blog.csdn.net
var socket;
if(!window.WebSocket){
window.WebSocket = window.MozWebSocket;
}
if(window.WebSocket){
socket = new WebSocket("ws://127.0.0.1:12345/ws");
socket.onmessage = function(event){
var ta = document.getElementById('responseText');
ta.value += event.data+"\r\n";
};
socket.onopen = function(event){
var ta = document.getElementById('responseText');
ta.value = "Netty-WebSocket服务器。。。。。。连接 \r\n";
};
socket.onclose = function(event){
var ta = document.getElementById('responseText');
ta.value = "Netty-WebSocket服务器。。。。。。关闭 \r\n";
};
}else{
alert("您的浏览器不支持WebSocket协议！");
}
function send(message){
if(!window.WebSocket){return;}
if(socket.readyState == WebSocket.OPEN){
socket.send(message);
}else{
alert("WebSocket 连接没有建立成功！");
}
}
</script>
</head>
<body>
<form onSubmit="return false;">
<label>ID</label><input type="text" name="uid" value="${uid!!}" /> <br />
<label>TEXT</label><input type="text" name="message" value="这里输入消息" /> <br />
<br /> <input type="button" value="发送ws消息"
onClick="send(this.form.uid.value+':'+this.form.message.value)" />
<hr color="black" />
<h3>服务端返回的应答消息</h3>
<textarea id="responseText" style="width: 1024px;height: 300px;"></textarea>
</form>
</body>
</html>
资料参考：
https://blog.csdn.net/u013184307/article/details/95479783
关于作者
王硕，网名信平，十多年软件开发经验，业余架构师，精通Java/Python/Go等，喜欢研究技术，著有《PyQt 5 快速开发与实战》《Python 3.* 全栈开发》，多个业余开源项目托管在GitHub上，欢迎微博交流。