SpringBoot+WebSocket+Netty实现消息推送的方法

 io.netty
 netty-all 
 4.1.33.Final



 cn.hutool
 hutool-all
 5.2.3

package com.sixj.nettypush.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 sixiaojie
 * @date 2020-03-28-15:07
 */
public class NettyConfig {
  /**
   * 定义一个channel组，管理所有的channel
   * GlobalEventExecutor.INSTANCE 是全局的事件执行器，是一个单例
   */
  private static ChannelGroup channelGroup = new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);

  /**
   * 存放用户与Chanel的对应信息，用于给指定用户发送消息
   */
  private static ConcurrentHashMap userChannelMap = new ConcurrentHashMap<>();

  private NettyConfig() {}
  
  /**
   * 获取channel组
   * @return
   */
  public static ChannelGroup getChannelGroup() {
    return channelGroup;
  }

  /**
   * 获取用户channel map
   * @return
   */
  public static ConcurrentHashMap getUserChannelMap(){
    return userChannelMap;
  }
}

package com.sixj.nettypush.websocket;

import io.netty.bootstrap.ServerBootstrap;
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.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.codec.serialization.ObjectEncoder;
import io.netty.handler.stream.ChunkedWriteHandler;
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 sixiaojie
 * @date 2020-03-28-13:44
 */

@Component
public class NettyServer{
  private static final Logger log = LoggerFactory.getLogger(NettyServer.class);
  /**
   * webSocket协议名
   */
  private static final String WEBSOCKET_PROTOCOL = "WebSocket";

  /**
   * 端口号
   */
  @Value("${webSocket.netty.port:58080}")
  private int port;

  /**
   * webSocket路径
   */
  @Value("${webSocket.netty.path:/webSocket}")
  private String webSocketPath;

  @Autowired
  private WebSocketHandler webSocketHandler;

  private EventLoopGroup bossGroup;
  private EventLoopGroup workGroup;

  /**
   * 启动
   * @throws InterruptedException
   */
  private void start() throws InterruptedException {
    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));
    // 连接到达时会创建一个通道
    bootstrap.childHandler(new ChannelInitializer() {

      @Override
      protected void initChannel(SocketChannel ch) throws Exception {
        // 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
        ch.pipeline().addLast(new HttpServerCodec());
        ch.pipeline().addLast(new ObjectEncoder());
        // 以块的方式来写的处理器
        ch.pipeline().addLast(new ChunkedWriteHandler());
        /*
        说明：
        1、http数据在传输过程中是分段的，HttpObjectAggregator可以将多个段聚合
        2、这就是为什么，当浏览器发送大量数据时，就会发送多次http请求
         */
        ch.pipeline().addLast(new HttpObjectAggregator(8192));
        /*
        说明：
        1、对应webSocket，它的数据是以帧（frame）的形式传递
        2、浏览器请求时 ws://localhost:58080/xxx 表示请求的uri
        3、核心功能是将http协议升级为ws协议，保持长连接
        */
        ch.pipeline().addLast(new WebSocketServerProtocolHandler(webSocketPath, WEBSOCKET_PROTOCOL, true, 65536 * 10));
        // 自定义的handler，处理业务逻辑
        ch.pipeline().addLast(webSocketHandler);

      }
    });
    // 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 = 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();
  }

  /**
   * 释放资源
   * @throws InterruptedException
   */
  @PreDestroy
  public void destroy() throws InterruptedException {
    if(bossGroup != null){
      bossGroup.shutdownGracefully().sync();
    }
    if(workGroup != null){
      workGroup.shutdownGracefully().sync();
    }
  }
  @PostConstruct()
  public void init() {
    //需要开启一个新的线程来执行netty server 服务器
    new Thread(() -> {
      try {
        start();
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }).start();
  }
}

package com.sixj.nettypush.websocket;

import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.sixj.nettypush.config.NettyConfig;
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;


/**
 * TextWebSocketFrame类型， 表示一个文本帧
 * @author sixiaojie
 * @date 2020-03-28-13:47
 */
@Component
@ChannelHandler.Sharable
public class WebSocketHandler extends SimpleChannelInboundHandler {
  private static final Logger log = LoggerFactory.getLogger(NettyServer.class);

  /**
   * 一旦连接，第一个被执行
   * @param ctx
   * @throws Exception
   */
  @Override
  public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
    log.info("handlerAdded 被调用"+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.getUserChannelMap().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 key = AttributeKey.valueOf("userId");
    ctx.channel().attr(key).setIfAbsent(uid);

    // 回复消息
    ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器连接成功！"));
  }

  @Override
  public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
    log.info("handlerRemoved 被调用"+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
   * @param ctx
   */
  private void removeUserId(ChannelHandlerContext ctx){
    AttributeKey key = AttributeKey.valueOf("userId");
    String userId = ctx.channel().attr(key).get();
    NettyConfig.getUserChannelMap().remove(userId);
  }
}

**第四步：**具体消息推送的接口
public interface PushService {
  /**
   * 推送给指定用户
   * @param userId
   * @param msg
   */
  void pushMsgToOne(String userId,String msg);

  /**
   * 推送给所有用户
   * @param msg
   */
  void pushMsgToAll(String msg);
}

import java.util.concurrent.ConcurrentHashMap;

/**
 * @author sixiaojie
 * @date 2020-03-30-20:10
 */
@Service
public class PushServiceImpl implements PushService {

  @Override
  public void pushMsgToOne(String userId, String msg){
    ConcurrentHashMap userChannelMap = NettyConfig.getUserChannelMap();
    Channel channel = userChannelMap.get(userId);
    channel.writeAndFlush(new TextWebSocketFrame(msg));
  }
  @Override
  public void pushMsgToAll(String msg){
    NettyConfig.getChannelGroup().writeAndFlush(new TextWebSocketFrame(msg));
  }
}

package com.sixj.nettypush.controller;

import com.sixj.nettypush.service.PushService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author sixiaojie
 * @date 2020-03-30-20:08
 */
@RestController
@RequestMapping("/push")
public class PushController {

  @Autowired
  private PushService pushService;

  /**
   * 推送给所有用户
   * @param msg
   */
  @PostMapping("/pushAll")
  public void pushToAll(@RequestParam("msg") String msg){
    pushService.pushMsgToAll(msg);
  }
  /**
   * 推送给指定用户
   * @param userId
   * @param msg
   */
  @PostMapping("/pushOne")
  public void pushMsgToOne(@RequestParam("userId") String userId,@RequestParam("msg") String msg){
    pushService.pushMsgToOne(userId,msg);
  }
}