websocket的介绍:
WebSocket是一种在网络通信中的协议,它是独立于HTTP协议的。该协议基于TCP/IP协议,可以提供双向通讯并保有状态。这意味着客户端和服务器可以进行实时响应,并且这种响应是双向的。WebSocket协议端口通常是80,443。
WebSocket的出现使得浏览器具备了实时双向通信的能力。与HTTP这种非持久单向响应应答的协议相比,WebSocket是一个持久化的协议。举例来说,即使在关闭网页或者浏览器后,WebSocket的连接仍然保持,用户也可以继续接收到服务器的消息。
此外,要建立WebSocket连接,需要浏览器和服务器握手进行建立连接。一旦连接建立,WebSocket可以在浏览器和服务器之间双向发送或接受信息。总的来说,WebSocket提供了一个高效、实时的双向通信方案。
1、用netty构建websocket服务器
package org.tianfan.websocket;// WebSocketServer.java
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
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;
public class WebSocketServer {
private final int port;
public WebSocketServer(int port) {
this.port = port;
}
public void run() throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline p = ch.pipeline();
p.addLast(new HttpServerCodec());
p.addLast(new HttpObjectAggregator(65536));
p.addLast(new WebSocketServerProtocolHandler("/websocket"));
p.addLast(new WebSocketServerHandler());
}
});
ChannelFuture f = b.bind(port).sync();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
int port = 8080;
if (args.length > 0) {
port = Integer.parseInt(args[0]);
}
new WebSocketServer(port).run();
}
}
我来解释一下上面的代码:
- p.addLast(new HttpServerCodec()):添加HTTP服务器编解码器,用于将数据转换成HTTP协议格式进行传输。
- p.addLast(new HttpObjectAggregator(65536)):添加HTTP对象聚合处理器,用于将HTTP请求或响应中的多个消息片段聚合成完整的消息。
- p.addLast(new WebSocketServerProtocolHandler("/websocket")):添加WebSocket协议处理器,用于处理WebSocket握手、消息传输等操作。
- p.addLast(new WebSocketServerHandler()):添加WebSocket处理器,用于处理客户端与服务器端之间的数据交换,实现自定义的业务逻辑。
使用Netty框架中的WebSocketServerProtocolHandler处理器,将HTTP升级为WebSocket协议。它创建了一个新的管道(pipeline)并将WebSocket处理程序添加到管道的尾部,以便处理WebSocket协议的握手和帧。"/websocket"是WebSocket的URI路径,它指定了WebSocket服务的相对地址,该地址将在客户端请求连接时被指定。
package org.tianfan.websocket;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
public class WebSocketServerHandler extends SimpleChannelInboundHandler<TextWebSocketFrame> {
@Override
public void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
// 处理消息
System.out.println("Received message: " + msg.text());
ctx.channel().writeAndFlush(new TextWebSocketFrame("Server received: " + msg.text()));
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
// 添加连接
System.out.println("Client connected: " + ctx.channel());
}
@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
// 断开连接
System.out.println("Client disconnected: " + ctx.channel());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
// 异常处理
cause.printStackTrace();
ctx.close();
}
}
我来解释一下上面的代码:
刚信息发过来的时候,在服务端打印,并写入前端。
2、前端客户端页面:
<!-- index.html -->
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>WebSocket Test</title>
</head>
<body>
<h1>WebSocket Test</h1>
<div>
<input type="text" id="message" placeholder="Message">
<button onclick="send()">Send</button>
</div>
<div id="output"></div>
<script>
var socket = new WebSocket("ws://localhost:8080/websocket");
socket.onopen = function(event) {
console.log("WebSocket opened: " + event);
};
socket.onmessage = function(event) {
console.log("WebSocket message received: " + event.data);
var output = document.getElementById("output");
output.innerHTML += "<p>" + event.data + "</p>";
};
socket.onclose = function(event) {
console.log("WebSocket closed: " + event);
};
function send() {
var message = document.getElementById("message").value;
socket.send(message);
}
</script>
</body>
</html>
运行结果: