Netty應用示例（四）websocket應用示例
摘要：
1、server端實現
原始碼實現：
public void run(int port){
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workGroup = new NioEvent...
1、server端實現
原始碼實現：
public void run(int port){
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workGroup = new NioEventLoopGroup();
try{
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
ChannelPipeline pipeline = sc.pipeline();
// 服務端，對請求解碼
pipeline.addLast("http-codec", new HttpServerCodec());
// 聚合器，把多個訊息轉換為一個單一的FullHttpRequest或是FullHttpResponse
pipeline.addLast("aggregator", new HttpObjectAggregator(65536));
// 塊寫入處理器
pipeline.addLast("http-chunked",new ChunkedWriteHandler());
//自定義處理器
pipeline.addLast("handler", new WebSocketServerHandler());
}
});
ChannelFuture cf = b.bind(port).sync();
System.out.println("Web socket server started at port " + port + '.');
System.out.println("Open your browser and navigate to http://localhost:" + port + '/');
cf.channel().closeFuture().sync();
}catch(Exception e){
e.printStackTrace();
}finally{
bossGroup.shutdownGracefully();
workGroup.shutdownGracefully();
}
}
- HttpServerCodec：將請求和應答訊息解碼為HTTP訊息
- HttpObjectAggregator：將HTTP訊息的多個部分合成一條完整的HTTP訊息
- ChunkedWriteHandler：向客戶端傳送HTML5檔案
2、WebsocketHandler實現
原始碼實現：
public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {
private static final Logger logger = Logger.getLogger(WebSocketServerHandler.class.getName());
private WebSocketServerHandshaker handshaker;
@Override
protected void messageReceived(ChannelHandlerContext ctx, Object obj)
throws Exception {
// 傳統的HTTP接入
if(obj instanceof FullHttpRequest){
handleHttpRequest(ctx,(FullHttpRequest)obj);
}
// WebSocket接入
else if(obj instanceof WebSocketFrame){
handleWebSocketFrame(ctx,(WebSocketFrame)obj);
}
}
private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) throws Exception{
System.out.println("handleHttpRequest");
// 如果HTTP解碼失敗，返回HHTP異常
if(!req.decoderResult().isSuccess() || (!"websocket".equals(req.headers().get("Upgrade")))){
sendHttpResponse(ctx,req,new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.BAD_REQUEST));
}
// 構造握手響應返回，本機測試
WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory("ws://localhost:8080/websocket", null, false);
handshaker =wsFactory.newHandshaker(req);
if(handshaker==null){
WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
}else{
handshaker.handshake(ctx.channel(), req);
}
}
private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame){
// 判斷是否是關閉鏈路的指令
if(frame instanceof CloseWebSocketFrame){
handshaker.close(ctx.channel(), (CloseWebSocketFrame)frame.retain());
return;
}
// 判斷是否是Ping訊息
if(frame instanceof PingWebSocketFrame){
ctx.channel().write(new PongWebSocketFrame(frame.content().retain()));
return;
}
// 本例程僅支援文字訊息，不支援二進位制訊息
if(!(frame instanceof TextWebSocketFrame)){
throw new UnsupportedOperationException(String.format("%s frame types not supported", frame.getClass().getName()));
}
// 返回應答訊息
String request = ((TextWebSocketFrame)frame).text();
if(logger.isLoggable(Level.FINE)){
logger.fine(String.format("%s received %s", ctx.channel(), request));
}
ctx.channel().write(new TextWebSocketFrame(request+ " , 歡迎使用Netty WebSocket服務，現在時刻："+ new java.util.Date().toString()));
}
private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res){
// 返回應答給客戶端
if(res.status().code() !=200){
ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(), CharsetUtil.UTF_8);
res.content().writeBytes(buf);
buf.release();
try {
Http2Headers http2Headers = HttpUtil.toHttp2Headers(res);
http2Headers.addLong(HttpHeaderNames.CONTENT_LENGTH, res.content().readableBytes());
}catch (Exception e){
e.printStackTrace();
}
}
// 如果是非Keep-Alive，關閉連線
ChannelFuture cf = ctx.channel().writeAndFlush(res);
try {
Http2Headers http2Headers = HttpUtil.toHttp2Headers(res);
Boolean keepAlive = Boolean.valueOf(http2Headers.get(HttpHeaderNames.CONTENT_LENGTH).toString());
if(!keepAlive || res.status().code() != 200){
cf.addListener(ChannelFutureListener.CLOSE);
}
}catch (Exception e){
e.printStackTrace();
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
throws Exception {
cause.printStackTrace();
ctx.close();
}
}
鏈路建立成功之前：
- 第一次握手由HTTP協議承載，所以是一個HTTP訊息，根據訊息頭中是否包含"Upgrade"欄位來判斷是否是websocket。
- 通過校驗後，構造WebSocketServerHandshaker，通過它構造握手響應資訊返回給客戶端，同時將WebSocket相關的編碼和解碼類動態新增到ChannelPipeline中。
鏈路建立成功之後：
- 客戶端通過文字框提交請求給服務端，Handler收到之後已經解碼之後的WebSocketFrame訊息。
- 如果是關閉按鏈路的指令就關閉鏈路
- 如果是維持鏈路的ping訊息就返回Pong訊息。
- 否則就返回應答訊息
3、測試結果
websocket測試工具：
http://coolaf.com/tool/chattest ，在瀏覽器中輸以上網址，可以看到如下介面：
測試工具.png
服務端輸出如下：
服務端輸出.png
客戶端傳送資料結果如下：
客戶端傳送資料.png