一、netty介绍
Netty 是一个基于NIO的客户、服务器端的编程框架，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相当于简化和流线化了网络应用的编程开发过程，例如：基于TCP和UDP的socket服务开发。快速”和“简单”并不用产生维护性或性能上的问题。Netty 是一个吸收了多种协议（包括FTP、SMTP、HTTP等各种二进制文本协议）的实现经验，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
二、工程搭建
实验目标：实现推送消息给指定的用户
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<parent>
<artifactId>springboot-demo</artifactId>
<groupId>com.et</groupId>
<version>1.0-SNAPSHOT</version>
</parent>
<modelVersion>4.0.0</modelVersion>
<artifactId>netty</artifactId>
<properties>
<maven.compiler.source>8</maven.compiler.source>
<maven.compiler.target>8</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-autoconfigure</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.87.Final</version>
</dependency>
<dependency>
<groupId>cn.hutool</groupId>
<artifactId>hutool-all</artifactId>
<version>5.6.1</version>
</dependency>
</dependencies>
</project>属性文件
server:
port: 8088netty server
package com.et.netty.server;
import com.et.netty.config.ProjectInitializer;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import java.net.InetSocketAddress;
/**
* @author dongliang7
* @projectName websocket-parent
* @ClassName NettyServer.java
* @description: TODO
* @createTime 2023年02月06日 16:41:00
*/
@Component
public class NettyServer {
static final Logger log = LoggerFactory.getLogger(NettyServer.class);
/**
* 端口号
*/
@Value("${webSocket.netty.port:8889}")
int port;
EventLoopGroup bossGroup;
EventLoopGroup workGroup;
@Autowired
ProjectInitializer nettyInitializer;
@PostConstruct
public void start() throws InterruptedException {
new Thread(() -> {
bossGroup = new NioEventLoopGroup();
workGroup = new NioEventLoopGroup();
ServerBootstrap bootstrap = new ServerBootstrap();
// bossGroup辅助客户端的tcp连接请求, workGroup负责与客户端之前的读写操作
bootstrap.group(bossGroup, workGroup);
// 设置NIO类型的channel
bootstrap.channel(NioServerSocketChannel.class);
// 设置监听端口
bootstrap.localAddress(new InetSocketAddress(port));
// 设置管道
bootstrap.childHandler(nettyInitializer);
// 配置完成，开始绑定server，通过调用sync同步方法阻塞直到绑定成功
ChannelFuture channelFuture = null;
try {
channelFuture = bootstrap.bind().sync();
log.info("Server started and listen on:{}", channelFuture.channel().localAddress());
// 对关闭通道进行监听
channelFuture.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
}
}).start();
}
/**
* 释放资源
*/
@PreDestroy
public void destroy() throws InterruptedException {
if (bossGroup != null) {
bossGroup.shutdownGracefully().sync();
}
if (workGroup != null) {
workGroup.shutdownGracefully().sync();
}
}
}ProjectInitializer
初始化，设置websocket handler
package com.et.netty.config;
import com.et.netty.handler.WebSocketHandler;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.socket.SocketChannel;
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.codec.serialization.ObjectEncoder;
import io.netty.handler.stream.ChunkedWriteHandler;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
/**
* @author dongliang7
* @projectName websocket-parent
* @ClassName ProjectInitializer.java
* @description: 管道配置
* @createTime 2023年02月06日 16:43:00
*/
@Component
public class ProjectInitializer extends ChannelInitializer<SocketChannel> {
/**
* webSocket协议名
*/
static final String WEBSOCKET_PROTOCOL = "WebSocket";
/**
* webSocket路径
*/
@Value("${webSocket.netty.path:/webSocket}")
String webSocketPath;
@Autowired
WebSocketHandler webSocketHandler;
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
// 设置管道
ChannelPipeline pipeline = socketChannel.pipeline();
// 流水线管理通道中的处理程序（Handler），用来处理业务
// webSocket协议本身是基于http协议的，所以这边也要使用http编解码器
pipeline.addLast(new HttpServerCodec());
pipeline.addLast(new ObjectEncoder());
// 以块的方式来写的处理器
pipeline.addLast(new ChunkedWriteHandler());
pipeline.addLast(new HttpObjectAggregator(8192));
pipeline.addLast(new WebSocketServerProtocolHandler(webSocketPath, WEBSOCKET_PROTOCOL, true, 65536 * 10));
// 自定义的handler，处理业务逻辑
pipeline.addLast(webSocketHandler);
}
}WebSocketHandler
package com.et.netty.handler;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.et.netty.config.NettyConfig;
import com.et.netty.server.NettyServer;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.AttributeKey;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
/**
* @author dongliang7
* @projectName websocket-parent
* @ClassName WebSocketHandler.java
* @description: TODO
* @createTime 2023年02月06日 16:44:00
*/
@Component
@ChannelHandler.Sharable
public class WebSocketHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
private static final Logger log = LoggerFactory.getLogger(NettyServer.class);
/**
* 一旦连接，第一个被执行
*/
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
log.info("有新的客户端链接：[{}]", ctx.channel().id().asLongText());
// 添加到channelGroup 通道组
NettyConfig.getChannelGroup().add(ctx.channel());
}
/**
* 读取数据
*/
@Override
protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
log.info("服务器收到消息：{}", msg.text());
// 获取用户ID,关联channel
JSONObject jsonObject = JSONUtil.parseObj(msg.text());
String uid = jsonObject.getStr("uid");
NettyConfig.getChannelMap().put(uid, ctx.channel());
// 将用户ID作为自定义属性加入到channel中，方便随时channel中获取用户ID
AttributeKey<String> key = AttributeKey.valueOf("userId");
ctx.channel().attr(key).setIfAbsent(uid);
// 回复消息
ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器收到消息啦"));
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
log.info("用户下线了:{}", ctx.channel().id().asLongText());
// 删除通道
NettyConfig.getChannelGroup().remove(ctx.channel());
removeUserId(ctx);
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
log.info("异常：{}", cause.getMessage());
// 删除通道
NettyConfig.getChannelGroup().remove(ctx.channel());
removeUserId(ctx);
ctx.close();
}
/**
* 删除用户与channel的对应关系
*/
private void removeUserId(ChannelHandlerContext ctx) {
AttributeKey<String> key = AttributeKey.valueOf("userId");
String userId = ctx.channel().attr(key).get();
NettyConfig.getChannelMap().remove(userId);
}
}NettyConfig
package com.et.netty.config;
import io.netty.channel.Channel;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.util.concurrent.GlobalEventExecutor;
import java.util.concurrent.ConcurrentHashMap;
/**
* @author dongliang7
* @projectName websocket-parent
* @ClassName NettyConfig.java
* @description: 管理全局Channel以及用户对应的channel（推送消息）
* @createTime 2023年02月06日 16:43:00
*/
public class NettyConfig {
/**
* 定义全局单利channel组 管理所有channel
*/
private static volatile ChannelGroup channelGroup = null;
/**
* 存放请求ID与channel的对应关系
*/
private static volatile ConcurrentHashMap<String, Channel> channelMap = null;
/**
* 定义两把锁
*/
private static final Object lock1 = new Object();
private static final Object lock2 = new Object();
public static ChannelGroup getChannelGroup() {
if (null == channelGroup) {
synchronized (lock1) {
if (null == channelGroup) {
channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
}
}
}
return channelGroup;
}
public static ConcurrentHashMap<String, Channel> getChannelMap() {
if (null == channelMap) {
synchronized (lock2) {
if (null == channelMap) {
channelMap = new ConcurrentHashMap<>();
}
}
}
return channelMap;
}
public static Channel getChannel(String userId) {
if (null == channelMap) {
return getChannelMap().get(userId);
}
return channelMap.get(userId);
}
}controller
package com.et.netty.controller;
import com.et.netty.service.PushMsgService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* @author dongliang7
* @projectName
* @ClassName TestController.java
* @description: TODO
* @createTime 2023年02月06日 17:48:00
*/
@RestController
@RequestMapping("/push")
public class TestController {
@Autowired
PushMsgService pushMsgService;
/**
* 推送消息到具体客户端
* @param uid
*/
@GetMapping("/{uid}")
public void pushOne(@PathVariable String uid) {
pushMsgService.pushMsgToOne(uid, "hello-------------------------");
}
/**
* 推送消息到所有客户端
*/
@GetMapping("/pushAll")
public void pushAll() {
pushMsgService.pushMsgToAll("hello all-------------------------");
}
}PushMsgService
package com.et.netty.service;
/**
* @author dongliang7
* @projectName websocket-parent
* @ClassName PushMsgService.java
* @description: 推送消息接口
* @createTime 2023年02月06日 16:44:00
*/
public interface PushMsgService {
/**
* 推送给指定用户
*/
void pushMsgToOne(String userId, String msg);
/**
* 推送给所有用户
*/
void pushMsgToAll(String msg);
}PushMsgServiceImpl
package com.et.netty.service;
import com.et.netty.config.NettyConfig;
import io.netty.channel.Channel;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import org.springframework.stereotype.Service;
import java.util.Objects;
/**
* @author dongliang7
* @projectName websocket-parent
* @ClassName PushMsgServiceImpl.java
* @description: 推送消息实现类
* @createTime 2023年02月06日 16:45:00
*/
@Service
public class PushMsgServiceImpl implements PushMsgService {
@Override
public void pushMsgToOne(String userId, String msg) {
Channel channel = NettyConfig.getChannel(userId);
if (Objects.isNull(channel)) {
throw new RuntimeException("未连接socket服务器");
}
channel.writeAndFlush(new TextWebSocketFrame(msg));
}
@Override
public void pushMsgToAll(String msg) {
NettyConfig.getChannelGroup().writeAndFlush(new TextWebSocketFrame(msg));
}
}文章值贴出部分关键代码，具体的详情代码参加代码仓库的netty模块
代码仓库
https://github.com/Harries/springboot-demo
三、测试
启动springboot工程
2024-03-08 11:21:32.975 INFO 10348 --- [ Thread-2] com.et.netty.server.NettyServer : Server started and listen on:/0:0:0:0:0:0:0:0:8889postman创建websocket连接 ws://127.0.0.1:8889/webSocket，并发送消息{'uid':'sss'}给服务端
打开浏览器，给用户sss推送消息 http://127.0.0.1:8088/push/sss
四、引用
https://www.cnblogs.com/dongl961230/p/17099057.html
http://www.liuhaihua.cn/archives/710299.html
