WebSocket长连接
一、创建服务端代码
1、MyServer 类
public class MyServer {
public static void main(String[] args) throws Exception{
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try{
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup,workerGroup).channel(NioServerSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO)) //增加日志处理器
.childHandler(new WebSocketChannelInitializer());
ChannelFuture channelFuture = serverBootstrap.bind(new InetSocketAddress(8899)).sync();
channelFuture.channel().closeFuture().sync();
}finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
2、WebSocketChannelInitializer 类
public class WebSocketChannelInitializer extends ChannelInitializer<SocketChannel>{
protected void initChannel(SocketChannel socketChannel) throws Exception {
ChannelPipeline pipeline = socketChannel.pipeline();
pipeline.addLast(new HttpServerCodec());
pipeline.addLast(new ChunkedWriteHandler());
pipeline.addLast(new HttpObjectAggregator(8192));
pipeline.addLast(new WebSocketServerProtocolHandler("/ws"));
pipeline.addLast(new TextWebSocketFrameHandle());
}
}
3、TextWebSocketFrameHandle 类
public class TextWebSocketFrameHandle extends SimpleChannelInboundHandler<TextWebSocketFrame> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, TextWebSocketFrame msg) throws Exception {
CommonUtil.println("收到消息:" + msg.text());
ctx.channel().writeAndFlush(new TextWebSocketFrame("服务器时间:" + LocalDateTime.now()));
}
@Override
public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
CommonUtil.println("handlerAdded:" +ctx.channel().id().asLongText());
}
@Override
public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
CommonUtil.println("handlerRemoved:" +ctx.channel().id().asLongText());
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
CommonUtil.println("异常发生");
ctx.close();
}
}
二、编写客户端WebSocket代码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>WebSocket</title>
</head>
<body>
<script type="text/javascript"> var socket; if(window.WebSocket){
socket = new WebSocket("ws://localhost:8899/ws");
socket.onmessage = function (event) {
var ta = document.getElementById("responseText");
ta.value = ta.value + "\n" + event.data;
}
socket.onopen = function (event) {
var ta = document.getElementById("responseText");
ta.value = "连接开启"; } socket.onclose = function (event) {
var ta = document.getElementById("responseText");
ta.value = ta.value + "\n" + "连接关闭！";
} }else {
alert("浏览器不支持WebSocket")
} function send(message) {
if(!window.WebSocket){
return;
}
if(socket.readyState == WebSocket.OPEN){
socket.send(message);
}else{
alert("连接尚未开启");
}
} </script>
<form onsubmit="return false">
<textarea name="message" style="width: 400px ; height: 200px;" ></textarea> <input type="button" value="发送数据" onclick="send(this.form.message.value)"> <h3>服务端输出:</h3> <textarea id="responseText" style="width: 400px ; height: 300px;" ></textarea> <input type="button" value="清空内容" onclick="javascript: document.getElementById('responseText').value=''">
</form>
</body>
</html>
三、测试
1、启动服务端
2、打开页面 http://localhost:7080/test.html
可以看到，连接开启。
服务端输出如下图：
四、进入页面的开发者模式
可以发现，
1、Status Code:101 Switching Protocols。 原来是Http的，切换成Socket
2、请求头： Upgrade:websocket
虽然请求发送的ws，但是要先发送的http请求建立连接，连接建立好后，将http升级到websockent协议上
五、测试发送消息
整个请求建立在webSocket协议之上。
六、连接关闭
当服务端停掉后，可以收到连接关闭。
七、websocket的请求和接收
如下图： Hello是请求， 服务器时间是接收