前驱知识
WebSocket
维基百科:
WebSocket是一种在单个TCP连接上进行全双工通信的协议。WebSocket通信协议于2011年被IETF定为标准RFC 6455,并由RFC7936补充规范。WebSocket API也被W3C定为标准。
WebSocket使得客户端和服务器之间的数据交换变得更加简单,允许服务端主动向客户端推送数据。在WebSocket API中,浏览器和服务器只需要完成一次握手,两者之间就直接可以创建持久性的连接,并进行双向数据传输。
添加maven依赖
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>8</source>
<target>8</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.25.Final</version>
</dependency>
</dependencies>
编写代码
Chat处理器
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.channel.group.ChannelGroup;
import io.netty.channel.group.DefaultChannelGroup;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.util.concurrent.GlobalEventExecutor;
import java.time.LocalDateTime;
/**
* @author: Tu9ohost
* 处理消息的handler
* TextWebSocketFrame: 在netty中,是用于为websocket专门处理文本的对象,frame是消息的载体
*/
public class ChatHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
// 用于记录和管理所有客户端的channle
private static ChannelGroup clients =
new DefaultChannelGroup(GlobalEventExecutor.INSTANCE);
@Override
protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg)
throws Exception {
// 获取客户端传输过来的消息
String content = msg.text();
System.out.println("接受到的数据:" + content);
// for (Channel channel: clients) {
// channel.writeAndFlush(
// new TextWebSocketFrame(
// "[服务器在]" + LocalDateTime.now()
// + "接受到消息, 消息为:" + content));
// }
// 下面这个方法,和上面的for循环,一致
clients.writeAndFlush(
new TextWebSocketFrame(
"[服务器在]" + LocalDateTime.now()
+ "接受到消息, 消息为:" + content));
}
/**
* 当客户端连接服务端之后(打开连接)
* 获取客户端的channle,并且放到ChannelGroup中去进行管理
*/
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
clients.add(ctx.channel());
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
// 当触发handlerRemoved,ChannelGroup会自动移除对应客户端的channel
// clients.remove(ctx.channel());
System.out.println("客户端断开,channle对应的长id为:"
+ ctx.channel().id().asLongText());
System.out.println("客户端断开,channle对应的短id为:"
+ ctx.channel().id().asShortText());
}
}
编写服务初始化
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.stream.ChunkedWriteHandler;
/**
* @author: Tu9ohost
*/
public class WSServerInitiazer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
// websocket 基于http协议,所以要有http编解码器
pipeline.addLast(new HttpServerCodec());
// 对写大数据流的支持
pipeline.addLast(new ChunkedWriteHandler());
// 对httpMessage进行聚合,聚合成FullHttpRequest或FullHttpResponse
// 几乎在netty中的编程,都会使用到此hanler
pipeline.addLast(new HttpObjectAggregator(1024*64));
// ====================== 以上是用于支持http协议 ======================
// ====================== 以下是支持httpWebsocket ======================
/**
* websocket 服务器处理的协议,用于指定给客户端连接访问的路由 : /ws
* 本handler会帮你处理一些繁重的复杂的事
* 会帮你处理握手动作: handshaking(close, ping, pong) ping + pong = 心跳
* 对于websocket来讲,都是以frames进行传输的,不同的数据类型对应的frames也不同
*/
pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
// 自定义的handler
pipeline.addLast(new ChatHandler());
}
}
主方法
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;
/**
* @author: Tu9ohost
*/
public class WSServer {
public static void main(String[] args) throws Exception {
EventLoopGroup mainGroup = new NioEventLoopGroup();
EventLoopGroup subGroup = new NioEventLoopGroup();
try {
ServerBootstrap server = new ServerBootstrap();
server.group(mainGroup, subGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new WSServerInitiazer());
// 定义了端口为8088
ChannelFuture future = server.bind(8088).sync();
future.channel().closeFuture().sync();
} finally {
mainGroup.shutdownGracefully();
subGroup.shutdownGracefully();
}
}
}
编写界面
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<div>发送消息:</div>
<input type="text" id="msgContent"/>
<input type="button" value="点我发送" onclick="CHAT.chat()"/>
<div>接受消息:</div>
<div id="receiveMsg" style="background-color: gainsboro;"></div>
<script type="application/javascript">
window.CHAT = {
socket: null,
init: function() {
if (window.WebSocket) {
CHAT.socket = new WebSocket("ws://127.0.0.1:8088/ws");
CHAT.socket.onopen = function() {
console.log("连接建立成功...");
},
CHAT.socket.onclose = function() {
console.log("连接关闭...");
},
CHAT.socket.onerror = function() {
console.log("发生错误...");
},
CHAT.socket.onmessage = function(e) {
console.log("接受到消息:" + e.data);
var receiveMsg = document.getElementById("receiveMsg");
var html = receiveMsg.innerHTML;
receiveMsg.innerHTML = html + "<br/>" + e.data;
}
} else {
alert("浏览器不支持websocket协议...");
}
},
chat: function() {
var msg = document.getElementById("msgContent");
CHAT.socket.send(msg.value);
}
};
CHAT.init();
</script>
</body>
</html>
检验
首先运行主方法,再打开界面,按F12,会显式链接建立成功
随意编写,再点击点我发送
服务端显式
关闭界面窗口,则会显式断开链接id