基于netty的websocket开发小结

最新推荐文章于 2025-05-25 16:28:10 发布

翻译最新推荐文章于 2025-05-25 16:28:10 发布 · 3.5k 阅读

文章标签：

#netty #websocket

netty 同时被 2 个专栏收录

3 篇文章

订阅专栏

websocket

1 篇文章

订阅专栏

本文介绍了WebSocket技术及其在HTML5中的应用，并详细探讨了基于Netty框架开发WebSocket的具体实现方式，包括握手验证过程和数据传输流程。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

基于netty的websocket开发小结

WebSocket是html5规范新引入的功能，用于解决浏览器与后台服务器双向通讯的问题，使用WebSocket技术，后台可以随时向前端推送消息，以保证前后台状态统一，在传统的无状态HTTP协议中，这是“无法做到”的。

WebSocket提出之前，为了解决后台推送消息到前台的需求，提出了一些解决方案，这些方案使用已有的技术（如ajax，iframe，flashplayer，java applet ...），通过一些变通的处理来实现。

webSocket是html5新引入的技术，允许后台随时向前端发送文本或者二进制消息，WebSocket是一种全新的协议，不属于http无状态协议，协议名为"ws"，这意味着一个websocket连接地址会是这样的写法：
ws://127.0.0.1:8080/websocket。ws不是http，所以传统的web服务器不一定支持，需要服务器与浏览器同时支持， WebSocket才能正常运行，目前的支持还不普遍，需要特别的web服务器和现代的浏览器。

浏览器对WebSocket的支持
Google Chrome浏览器最先支持WebSocket，随后是Safari，Firefox，此外最新版本的Opera和IE（Opera11，IE10）也支持WebSocket。

客户端WebSocket的主要方法

1 构造函数

Java代码

var websocket = new WebSocket("ws://127.0.0.1:8080/websocket");

Java代码

var websocket = new WebSocket("ws://127.0.0.1:8080/websocket");

2 事件open/message/close/error
WebSocket#onopen, onmessage, onclose, onerror
连接打开时，回调onopen方法，接收到后台消息时会触发到onmessage事件，后台关闭时调用onclose，出现连接异常时可在onerror中捕获
发送消息 - WebSocket#send(data)
关闭连接 - WebSocket#close(optional code, optional reason)

下面是一个简单的html5连接websocket服务器测试页

Html代码

<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" charset="utf-8" >
windowwindow.WebSocket = window.WebSocket || window.MozWebSocket;
if (!window.WebSocket){
alert("WebSocket not supported by this browser");
return;
};
var websocket = new WebSocket("ws://127.0.0.1:8080/websocket");
websocket.onmessage = function(evt){
var data = evt.data;
alert("received message: " + data);
}
function send() {
var name = document.querySelector("input[namename=name]").value;
alert("websocket send message:"+name);
websocket.send(name);
}
</script>
</head>
<body>
<label for="name">What’s your name:</label>
<input type="text" id="name" name="name" />
<button onclick="send()">Send</button>
<div id="message" style="color:red"></div>
</body>
</html>

Html代码

<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" charset="utf-8" >
windowwindow.WebSocket = window.WebSocket || window.MozWebSocket;
if (!window.WebSocket){
alert("WebSocket not supported by this browser");
return;
};
var websocket = new WebSocket("ws://127.0.0.1:8080/websocket");
websocket.onmessage = function(evt){
var data = evt.data;
alert("received message: " + data);
}
function send() {
var name = document.querySelector("input[namename=name]").value;
alert("websocket send message:"+name);
websocket.send(name);
}
</script>
</head>
<body>
<label for="name">What’s your name:</label>
<input type="text" id="name" name="name" />
<button onclick="send()">Send</button>
<div id="message" style="color:red"></div>
</body>
</html>

服务器对WebSocket的支持
    WebSocket不同于http协议，传统的web服务器通常不支持WebSocket.而websocket服务器端的开发大概有借助 Socket.IO开发、NodeJS和Socket.IO联合开发以及借助netty框架开发等等。这里只对netty框架下的websocket开发进行一个简单的说明！

    websocket的协议比较简单, 客户端和普通的浏览器一样通过80或者443端口和服务器进行请求握手,服务器根据http header识别是否一个websocket请求,如果是,则将请求升级为一个websocket连接,握手成功后就进入双向长连接的数据传输阶段. websocket的数据传输是基于帧的方式: 0x00 表示数据开始, 0xff表示数据结束,数据以utf-8编码.

    简单的说，第一次请求客户端发送的是http请求，请求头中包含websocket相关的信息，服务器端对请求进行验证：

Java代码

private void handleHttpRequest(ChannelHandlerContext ctx, HttpRequest req) throws Exception {
// Allow only GET methods.
if (req.getMethod() != GET) {
sendHttpResponse(ctx, req, new DefaultHttpResponse(HTTP_1_1, FORBIDDEN));
return;
}
// Send the demo page and favicon.ico
if (req.getUri().equals("/")) {
HttpResponse res = new DefaultHttpResponse(HTTP_1_1, OK);
ChannelBuffer content = WebSocketServerIndexPage.getContent(getWebSocketLocation(req));
res.setHeader(CONTENT_TYPE, "text/html; charset=UTF-8");
setContentLength(res, content.readableBytes());
res.setContent(content);
sendHttpResponse(ctx, req, res);
return;
} else if (req.getUri().equals("/favicon.ico")) {
HttpResponse res = new DefaultHttpResponse(HTTP_1_1, NOT_FOUND);
sendHttpResponse(ctx, req, res);
return;
}
// Handshake
WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
this.getWebSocketLocation(req), null, false);
this.handshaker = wsFactory.newHandshaker(req);
if (this.handshaker == null) {
wsFactory.sendUnsupportedWebSocketVersionResponse(ctx.getChannel());
} else {
this.handshaker.handshake(ctx.getChannel(), req);
System.out.println(WebSocketServer.recipients.size());
WebSocketServer.recipients.add(ctx.getChannel());
System.out.println(WebSocketServer.recipients.size());
System.out.println(ctx.getChannel().getId());
}
}

Java代码

private void handleHttpRequest(ChannelHandlerContext ctx, HttpRequest req) throws Exception {
// Allow only GET methods.
if (req.getMethod() != GET) {
sendHttpResponse(ctx, req, new DefaultHttpResponse(HTTP_1_1, FORBIDDEN));
return;
}
// Send the demo page and favicon.ico
if (req.getUri().equals("/")) {
HttpResponse res = new DefaultHttpResponse(HTTP_1_1, OK);
ChannelBuffer content = WebSocketServerIndexPage.getContent(getWebSocketLocation(req));
res.setHeader(CONTENT_TYPE, "text/html; charset=UTF-8");
setContentLength(res, content.readableBytes());
res.setContent(content);
sendHttpResponse(ctx, req, res);
return;
} else if (req.getUri().equals("/favicon.ico")) {
HttpResponse res = new DefaultHttpResponse(HTTP_1_1, NOT_FOUND);
sendHttpResponse(ctx, req, res);
return;
}
// Handshake
WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
this.getWebSocketLocation(req), null, false);
this.handshaker = wsFactory.newHandshaker(req);
if (this.handshaker == null) {
wsFactory.sendUnsupportedWebSocketVersionResponse(ctx.getChannel());
} else {
this.handshaker.handshake(ctx.getChannel(), req);
System.out.println(WebSocketServer.recipients.size());
WebSocketServer.recipients.add(ctx.getChannel());
System.out.println(WebSocketServer.recipients.size());
System.out.println(ctx.getChannel().getId());
}
}

验证成功后，将请求升级为一个websocket连接，之后的通信就进入双向长连接的数据传输阶段。

Java代码

private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
// Check for closing frame
if (frame instanceof CloseWebSocketFrame) {
this.handshaker.close(ctx.getChannel(), (CloseWebSocketFrame) frame);
return;
} else if (frame instanceof PingWebSocketFrame) {
ctx.getChannel().write(new PongWebSocketFrame(frame.getBinaryData()));
return;
} else if (!(frame instanceof TextWebSocketFrame)) {
throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass()
.getName()));
}
// Send the uppercase string back.
String request = ((TextWebSocketFrame) frame).getText();
logger.debug(String.format("Channel %s received %s", ctx.getChannel().getId(), request));
WebSocketServer.recipients.write(new TextWebSocketFrame(request.toUpperCase()));
ctx.getChannel().write(new TextWebSocketFrame(request.toUpperCase()));
}

Java代码

private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {
// Check for closing frame
if (frame instanceof CloseWebSocketFrame) {
this.handshaker.close(ctx.getChannel(), (CloseWebSocketFrame) frame);
return;
} else if (frame instanceof PingWebSocketFrame) {
ctx.getChannel().write(new PongWebSocketFrame(frame.getBinaryData()));
return;
} else if (!(frame instanceof TextWebSocketFrame)) {
throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass()
.getName()));
}
// Send the uppercase string back.
String request = ((TextWebSocketFrame) frame).getText();
logger.debug(String.format("Channel %s received %s", ctx.getChannel().getId(), request));
WebSocketServer.recipients.write(new TextWebSocketFrame(request.toUpperCase()));
ctx.getChannel().write(new TextWebSocketFrame(request.toUpperCase()));
}

一定要注意在messageReceived中要对HttpRequest和WebSocketFrame分别进行处理。

Java代码

public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
Object msg = e.getMessage();
if (msg instanceof HttpRequest) {
handleHttpRequest(ctx, (HttpRequest) msg);
} else if (msg instanceof WebSocketFrame) {
handleWebSocketFrame(ctx, (WebSocketFrame) msg);
}
}

Java代码

public void messageReceived(ChannelHandlerContext ctx, MessageEvent e) throws Exception {
Object msg = e.getMessage();
if (msg instanceof HttpRequest) {
handleHttpRequest(ctx, (HttpRequest) msg);
} else if (msg instanceof WebSocketFrame) {
handleWebSocketFrame(ctx, (WebSocketFrame) msg);
}
}

服务入口

Java代码

package com.etao.mobile.websocket;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.group.ChannelGroup;
import org.jboss.netty.channel.group.DefaultChannelGroup;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
/**
* A HTTP server which serves Web Socket requests at:
*
* http://localhost:8080/websocket
*
* Open your browser at http://localhost:8080/, then the demo page will be
* loaded and a Web Socket connection will be made automatically.
*
* This server illustrates support for the different web socket specification
* versions and will work with:
*
* <ul>
* <li>Safari 5+ (draft-ietf-hybi-thewebsocketprotocol-00)
* <li>Chrome 6-13 (draft-ietf-hybi-thewebsocketprotocol-00)
* <li>Chrome 14+ (draft-ietf-hybi-thewebsocketprotocol-10)
* <li>Chrome 16+ (RFC 6455 aka draft-ietf-hybi-thewebsocketprotocol-17)
* <li>Firefox 7+ (draft-ietf-hybi-thewebsocketprotocol-10)
* </ul>
*/
public class WebSocketServer {
private final int port;
public static ChannelGroup recipients = new DefaultChannelGroup();
public WebSocketServer(int port) {
this.port = port;
}
public void run() {
// Configure the server.
ServerBootstrap bootstrap = new ServerBootstrap(
new NioServerSocketChannelFactory(Executors
.newCachedThreadPool(), Executors.newCachedThreadPool()));
// Set up the event pipeline factory.
bootstrap.setPipelineFactory(new WebSocketServerPipelineFactory());
// Bind and start to accept incoming connections.
bootstrap.bind(new InetSocketAddress(port));
System.out.println("Web socket server started at port " + port + '.');
System.out
.println("Open your browser and navigate to http://localhost:"
+ port + '/');
}
public static void main(String[] args) {
int port;
if (args.length > 0) {
port = Integer.parseInt(args[0]);
} else {
port = 8080;
}
new WebSocketServer(port).run();
}
}

Java代码

package com.etao.mobile.websocket;
import java.net.InetSocketAddress;
import java.util.concurrent.Executors;
import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.group.ChannelGroup;
import org.jboss.netty.channel.group.DefaultChannelGroup;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
/**
* A HTTP server which serves Web Socket requests at:
*
* http://localhost:8080/websocket
*
* Open your browser at http://localhost:8080/, then the demo page will be
* loaded and a Web Socket connection will be made automatically.
*
* This server illustrates support for the different web socket specification
* versions and will work with:
*
* <ul>
* <li>Safari 5+ (draft-ietf-hybi-thewebsocketprotocol-00)
* <li>Chrome 6-13 (draft-ietf-hybi-thewebsocketprotocol-00)
* <li>Chrome 14+ (draft-ietf-hybi-thewebsocketprotocol-10)
* <li>Chrome 16+ (RFC 6455 aka draft-ietf-hybi-thewebsocketprotocol-17)
* <li>Firefox 7+ (draft-ietf-hybi-thewebsocketprotocol-10)
* </ul>
*/
public class WebSocketServer {
private final int port;
public static ChannelGroup recipients = new DefaultChannelGroup();
public WebSocketServer(int port) {
this.port = port;
}
public void run() {
// Configure the server.
ServerBootstrap bootstrap = new ServerBootstrap(
new NioServerSocketChannelFactory(Executors
.newCachedThreadPool(), Executors.newCachedThreadPool()));
// Set up the event pipeline factory.
bootstrap.setPipelineFactory(new WebSocketServerPipelineFactory());
// Bind and start to accept incoming connections.
bootstrap.bind(new InetSocketAddress(port));
System.out.println("Web socket server started at port " + port + '.');
System.out
.println("Open your browser and navigate to http://localhost:"
+ port + '/');
}
public static void main(String[] args) {
int port;
if (args.length > 0) {
port = Integer.parseInt(args[0]);
} else {
port = 8080;
}
new WebSocketServer(port).run();
}
}

一定要注意的是netty3.0一下的版本是不支持websocket的！我这里用的是3.3.0.Final版本。

可能存在的隐患：不同草案的websocket 握手标准有所不同，因此netty在这方面的检测是否可以满足要求？

我这里也参考了基于Websocket草案10协议的升级及基于Netty的握手实现，在此对冯立彬的博客表示感谢！