java netty 实现 websocket 服务端和客户端双向通信 实现心跳和断线重连

maven依赖

<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.97.Final</version>
</dependency>

服务端

一个接口 IGetHandshakeFuture

package com.sux.demo.websocket2;

import io.netty.channel.ChannelPromise;

public interface IGetHandshakeFuture {
ChannelPromise getHandshakeFuture();
}

服务端心跳 ServerHeartbeatHandler

package com.sux.demo.websocket2;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent; public class ServerHeartbeatHandler extends ChannelInboundHandlerAdapter {
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
if (evt instanceof IdleStateEvent) {
IdleStateEvent event = (IdleStateEvent) evt;
if (event.state() == IdleState.READER_IDLE) { // 读空闲
// System.out.println("关闭客户端连接, channel id=" + ctx.channel().id());
// ctx.channel().close();
} else if (event.state() == IdleState.WRITER_IDLE) { // 写空闲
System.out.println("服务端向客户端发送心跳");
ctx.writeAndFlush(new PongWebSocketFrame());
} else if (event.state() == IdleState.ALL_IDLE) { // 读写空闲 }
}
}
}

服务端封装 WebSocketServer

package com.sux.demo.websocket2;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
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.timeout.IdleStateHandler; import java.util.concurrent.TimeUnit; public class WebSocketServer {
private EventLoopGroup bossGroup;
private EventLoopGroup workerGroup; public WebSocketServer() {
//创建两个线程组 boosGroup、workerGroup
bossGroup = new NioEventLoopGroup();
workerGroup = new NioEventLoopGroup();
} public void start(int port, WebSocketServerHandler handler, String name) {
try {
//创建服务端的启动对象,设置参数
ServerBootstrap bootstrap = new ServerBootstrap();
//设置两个线程组boosGroup和workerGroup
bootstrap.group(bossGroup, workerGroup)
//设置服务端通道实现类型
.channel(NioServerSocketChannel.class)
//设置线程队列得到连接个数
.option(ChannelOption.SO_BACKLOG, 128)
//设置保持活动连接状态
.childOption(ChannelOption.SO_KEEPALIVE, true)
//使用匿名内部类的形式初始化通道对象
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel) throws Exception {
//给pipeline管道设置处理器
socketChannel.pipeline().addLast(new HttpServerCodec());
socketChannel.pipeline().addLast(new HttpObjectAggregator(65536));
socketChannel.pipeline().addLast(new WebSocketServerProtocolHandler("/websocket"));
socketChannel.pipeline().addLast(new IdleStateHandler(5, 2, 0, TimeUnit.SECONDS));
socketChannel.pipeline().addLast(new ServerHeartbeatHandler());
socketChannel.pipeline().addLast(handler);
}
});//给workerGroup的EventLoop对应的管道设置处理器
//绑定端口号,启动服务端
ChannelFuture channelFuture = bootstrap.bind(port).sync();
System.out.println(name + " 已启动");
//对通道关闭进行监听
channelFuture.channel().closeFuture().sync();
} catch (InterruptedException e) {
e.printStackTrace();
} finally { }
}
}

服务端消息处理 WebSocketServerHandler

package com.sux.demo.websocket2;

import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.handler.codec.http.websocketx.*;
import io.netty.util.CharsetUtil; import java.util.ArrayList;
import java.util.List; @ChannelHandler.Sharable
public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> { private List<Channel> channelList; public WebSocketServerHandler() {
channelList = new ArrayList<>();
} public boolean hasClient() {
return channelList.size() > 0;
} @Override
protected void channelRead0(ChannelHandlerContext ctx, Object msg) {
if (msg instanceof PingWebSocketFrame) {
System.out.println("收到客户端" + ctx.channel().remoteAddress() + "发来的心跳:PING");
} if (msg instanceof TextWebSocketFrame) {
TextWebSocketFrame frame = (TextWebSocketFrame) msg;
System.out.println("收到客户端" + ctx.channel().remoteAddress() + "发来的消息:" + frame.text());
/*for (Channel channel : channelList) {
if (!ctx.channel().id().toString().equals(channel.id().toString())) {
channel.writeAndFlush(new TextWebSocketFrame(Unpooled.copiedBuffer(frame.text(), CharsetUtil.UTF_8)));
System.out.println("服务端向客户端 " + channel.id().toString() + " 转发消息:" + frame.text());
}
}*/
}
} @Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
channelList.add(ctx.channel());
System.out.println("客户端连接:" + ctx.channel().id().toString());
} @Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
channelList.remove(ctx.channel());
} @Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
} @Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
channelList.remove(ctx.channel());
} public void send(String text) {
for (Channel channel : channelList) {
channel.writeAndFlush(new TextWebSocketFrame(Unpooled.copiedBuffer(text, CharsetUtil.UTF_8)));
}
}
}

服务端测试主机 WebSocketClientHost

package com.sux.demo.websocket2;

import io.netty.buffer.Unpooled;
import io.netty.channel.Channel;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.CharsetUtil; public class WebSocketClientHost {
public static void main(String[] args) {
WebSocketClient webSocketClient = new WebSocketClient(); SendDataToServerThread thread = new SendDataToServerThread(webSocketClient);
thread.start(); webSocketClient.connect("127.0.0.1", 40005, "WebSocket客户端");
}
} class SendDataToServerThread extends Thread {
private WebSocketClient webSocketClient; private int index = 1; public SendDataToServerThread(WebSocketClient webSocketClient) {
this.webSocketClient = webSocketClient;
} @Override
public void run() {
try {
while (index <= 5) {
Channel channel = webSocketClient.getChannel();
if (channel != null && channel.isActive()) {
String msg = "客户端发送的测试消息, index= " + index;
channel.writeAndFlush(new TextWebSocketFrame(Unpooled.copiedBuffer(msg, CharsetUtil.UTF_8)));
index++;
}
Thread.sleep(1000);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

客户端

客户端心跳 ClientHeartbeatHandler

package com.sux.demo.websocket2;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent; public class ClientHeartbeatHandler extends ChannelInboundHandlerAdapter {
@Override
public void userEventTriggered(ChannelHandlerContext ctx, Object evt) {
if (evt instanceof IdleStateEvent) {
IdleStateEvent event = (IdleStateEvent) evt;
if (event.state() == IdleState.READER_IDLE) { // 读空闲
System.out.println("断线重连");
ctx.channel().close();
} else if (event.state() == IdleState.WRITER_IDLE) { // 写空闲
System.out.println("客户端向服务端发送心跳");
ctx.writeAndFlush(new PingWebSocketFrame());
// ctx.writeAndFlush(new TextWebSocketFrame(Unpooled.copiedBuffer("PING", CharsetUtil.UTF_8)));
} else if (event.state() == IdleState.ALL_IDLE) { // 读写空闲 }
}
}
}

客户端封装 WebSocketClient

package com.sux.demo.websocket2;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.DefaultHttpHeaders;
import io.netty.handler.codec.http.HttpClientCodec;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.websocketx.WebSocketClientHandshaker;
import io.netty.handler.codec.http.websocketx.WebSocketClientHandshakerFactory;
import io.netty.handler.codec.http.websocketx.WebSocketClientProtocolHandler;
import io.netty.handler.codec.http.websocketx.WebSocketVersion;
import io.netty.handler.timeout.IdleStateHandler; import java.net.URI;
import java.net.URISyntaxException;
import java.util.concurrent.TimeUnit; public class WebSocketClient {
private NioEventLoopGroup eventExecutors; private Channel channel; public WebSocketClient() {
eventExecutors = new NioEventLoopGroup();
} public Channel getChannel() {
return channel;
} public void connect(String ip, int port, String name) {
try {
WebSocketClientHandshaker handshaker = WebSocketClientHandshakerFactory.newHandshaker(
new URI("ws://" + ip + ":" + port + "/websocket"), WebSocketVersion.V13, null, false, new DefaultHttpHeaders());
WebSocketClientHandler handler = new WebSocketClientHandler(handshaker);
ClientHeartbeatHandler heartbeatHandler = new ClientHeartbeatHandler(); //创建bootstrap对象,配置参数
Bootstrap bootstrap = new Bootstrap();
//设置线程组
bootstrap.group(eventExecutors)
//设置客户端的通道实现类型
.channel(NioSocketChannel.class)
//使用匿名内部类初始化通道
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
//添加客户端通道的处理器
ch.pipeline().addLast(new HttpClientCodec());
ch.pipeline().addLast(new HttpObjectAggregator(65536));
ch.pipeline().addLast(new WebSocketClientProtocolHandler(handshaker, true, false));
ch.pipeline().addLast(new IdleStateHandler(5, 2, 0, TimeUnit.SECONDS));
ch.pipeline().addLast(heartbeatHandler);
ch.pipeline().addLast(handler);
}
}); // 连接服务端
ChannelFuture channelFuture = bootstrap.connect(ip, port); // 在连接关闭后尝试重连
channelFuture.channel().closeFuture().addListener(future -> {
try {
Thread.sleep(2000);
System.out.println("重新连接");
connect(ip, port, name); // 重新连接
} catch (Exception e) {
e.printStackTrace();
}
}); channelFuture.sync(); // 等待握手完成
// IGetHandshakeFuture getHadnshakeFuture = handler;
// getHadnshakeFuture.getHandshakeFuture().sync(); channel = channelFuture.channel();
System.out.println(name + " 已启动"); //对通道关闭进行监听
channelFuture.channel().closeFuture().sync();
} catch (InterruptedException | URISyntaxException e) {
e.printStackTrace();
} finally { }
} }

客户端消息处理 WebSocketClientHandler

package com.sux.demo.websocket2;

import io.netty.channel.*;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.websocketx.*; @ChannelHandler.Sharable
public class WebSocketClientHandler extends SimpleChannelInboundHandler<Object> implements IGetHandshakeFuture {
private WebSocketClientHandshaker handshaker;
private ChannelPromise handshakeFuture; public WebSocketClientHandler(WebSocketClientHandshaker handshaker) {
this.handshaker = handshaker;
} public ChannelPromise getHandshakeFuture() {
return this.handshakeFuture;
} @Override
protected void channelRead0(ChannelHandlerContext ctx, Object msg) throws Exception {
if (!handshaker.isHandshakeComplete()) {
try {
handshaker.finishHandshake(ctx.channel(), (FullHttpResponse) msg);
handshakeFuture.setSuccess();
} catch (WebSocketHandshakeException e) {
handshakeFuture.setFailure(e);
}
return;
} if (msg instanceof PongWebSocketFrame) {
System.out.println("收到服务端" + ctx.channel().remoteAddress() + "发来的心跳:PONG");
} if (msg instanceof TextWebSocketFrame) {
TextWebSocketFrame frame = (TextWebSocketFrame) msg;
System.out.println("收到服务端" + ctx.channel().remoteAddress() + "发来的消息:" + frame.text()); // 接收服务端发送过来的消息
}
} @Override
public void handlerAdded(ChannelHandlerContext ctx) {
handshakeFuture = ctx.newPromise();
} @Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
// handshaker.handshake(ctx.channel());
} @Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception { } @Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
} @Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}

客户端测试主机 WebSocketServerHost

package com.sux.demo.websocket2;

public class WebSocketServerHost {
public static void main(String[] args) {
WebSocketServerHandler handler = new WebSocketServerHandler();
WebSocketServer webSocketServer = new WebSocketServer(); SendDataToClientThread thread = new SendDataToClientThread(handler);
thread.start(); webSocketServer.start(40005, handler, "WebSocket服务端");
}
} class SendDataToClientThread extends Thread {
private WebSocketServerHandler handler; private int index = 1; public SendDataToClientThread(WebSocketServerHandler handler) {
this.handler = handler;
} @Override
public void run() {
try {
while (index <= 5) {
if (handler.hasClient()) {
String msg = "服务端发送的测试消息, index= " + index;
handler.send(msg);
index++;
}
Thread.sleep(1000);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

测试

测试一

步骤:先启动服务端,再启动客户端

现象:客户端与服务端互发消息,消息发完后,互发心跳

测试二

步骤:先启动服务端,再启动客户端,然后关闭服务端,过一会再启动服务端

现象:客户端断线重连,通信恢复,正常发消息和心跳

测试三

步骤:先启动客户端,过一会再启动服务端

现象:服务端启动后,客户端连上服务端,正常通信,互发消息,消息发完互发心跳

遇到的问题

以上测试,客户端可以收到服务端发送的心跳,但是服务端无法收到客户端发送的心跳,导致服务端触发读空闲,从而关闭连接(代码已注释掉)

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