Java tutorial
/* * Copyright 2012 The Netty Project * * The Netty Project licenses this file to you under the Apache License, * version 2.0 (the "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. */ package com.brainlounge.zooterrain.netty; import com.brainlounge.zooterrain.zkclient.ClientMessage; import com.brainlounge.zooterrain.zkclient.ClientRequest; import com.brainlounge.zooterrain.zkclient.ControlMessage; import com.brainlounge.zooterrain.zkclient.DataMessage; import com.brainlounge.zooterrain.zkclient.ZkStateListener; import com.brainlounge.zooterrain.zkclient.ZkStateObserver; import com.fasterxml.jackson.core.JsonParser; import com.fasterxml.jackson.core.TreeNode; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.TextNode; import com.google.common.collect.Sets; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.handler.codec.http.DefaultFullHttpResponse; import io.netty.handler.codec.http.FullHttpRequest; import io.netty.handler.codec.http.FullHttpResponse; import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame; import io.netty.handler.codec.http.websocketx.PingWebSocketFrame; import io.netty.handler.codec.http.websocketx.PongWebSocketFrame; import io.netty.handler.codec.http.websocketx.TextWebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory; import io.netty.util.CharsetUtil; import java.util.logging.Level; import java.util.logging.Logger; import static io.netty.handler.codec.http.HttpHeaders.Names.*; import static io.netty.handler.codec.http.HttpHeaders.*; import static io.netty.handler.codec.http.HttpMethod.*; import static io.netty.handler.codec.http.HttpResponseStatus.*; import static io.netty.handler.codec.http.HttpVersion.*; /** * Handles handshakes and messages */ public class WebSocketServerInboundHandler extends SimpleChannelInboundHandler<Object> { private static final Logger logger = Logger.getLogger(WebSocketServerInboundHandler.class.getName()); private static final String WEBSOCKET_PATH = "/firehose"; protected WebSocketServerHandshaker handshaker; protected ZkStateObserver zkStateObserver; protected ObjectMapper jsonMapper = new ObjectMapper(); public WebSocketServerInboundHandler(ZkStateObserver zkStateObserver) { this.zkStateObserver = zkStateObserver; } public void messageReceived(ChannelHandlerContext ctx, Object msg) throws Exception { if (msg instanceof FullHttpRequest) { handleHttpRequest(ctx, (FullHttpRequest) msg); } else if (msg instanceof WebSocketFrame) { handleWebSocketFrame(ctx, (WebSocketFrame) msg); } } @Override public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ctx.flush(); } private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) throws Exception { // Handle a bad request. if (!req.getDecoderResult().isSuccess()) { sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST)); return; } // Allow only GET methods. if (req.getMethod() != GET) { sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN)); return; } // Send the demo page and favicon.ico if ("/favicon.ico".equals(req.getUri())) { FullHttpResponse res = new DefaultFullHttpResponse(HTTP_1_1, NOT_FOUND); sendHttpResponse(ctx, req, res); return; } else if ("/hexdump.js".equals(req.getUri())) { final WebSocketServerJSPage webSocketServerJSPage = new WebSocketServerJSPage(); ByteBuf content = webSocketServerJSPage.getContent(getWebSocketLocation(req)); sendHttpResponse(ctx, req, content, "text/javascript; charset=UTF-8"); return; } else if ("/".equals(req.getUri())) { WebSocketServerIndexPage webSocketServerIndexPage = new WebSocketServerIndexPage(); ByteBuf content = webSocketServerIndexPage.getContent(getWebSocketLocation(req)); sendHttpResponse(ctx, req, content, "text/html; charset=UTF-8"); return; } // Handshake WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(getWebSocketLocation(req), null, false); handshaker = wsFactory.newHandshaker(req); if (handshaker == null) { WebSocketServerHandshakerFactory.sendUnsupportedWebSocketVersionResponse(ctx.channel()); } else { handshaker.handshake(ctx.channel(), req); zkStateObserver.addListener(new OutboundConnector(ctx)); } } private void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, ByteBuf content, String contentType) { FullHttpResponse res = new DefaultFullHttpResponse(HTTP_1_1, OK, content); res.headers().set(CONTENT_TYPE, contentType); setContentLength(res, content.readableBytes()); sendHttpResponse(ctx, req, res); } private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) { // Check for closing frame if (frame instanceof CloseWebSocketFrame) { handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain()); return; } if (frame instanceof PingWebSocketFrame) { ctx.channel().write(new PongWebSocketFrame(frame.content().retain())); return; } if (!(frame instanceof TextWebSocketFrame)) { throw new UnsupportedOperationException( String.format("%s frame types not supported", frame.getClass().getName())); } String request = ((TextWebSocketFrame) frame).text(); if (logger.isLoggable(Level.FINE)) { logger.fine(String.format("%s received %s", ctx.channel(), request)); } // expecting JSON, parse now TreeNode jsonRequest; ClientRequest.Type requestType; try { final JsonParser parser = jsonMapper.getFactory().createParser(request); jsonRequest = parser.readValueAsTree(); TextNode type = (TextNode) jsonRequest.get("r"); requestType = ClientRequest.Type.valueOf(type.textValue()); } catch (Exception e) { logger.info("parsing JSON failed for '" + request + "'"); // TODO return error to client return; } if (requestType == ClientRequest.Type.i) { // client requested initial data // sending connection string info final ControlMessage handshakeInfo = new ControlMessage(zkStateObserver.getZkConnection(), ControlMessage.Type.H); writeClientMessage(ctx, handshakeInfo); // sending initial znodes try { zkStateObserver.initialTree("/", 6, Sets.<ZkStateListener>newHashSet(new OutboundConnector(ctx))); } catch (InterruptedException e) { e.printStackTrace(); } } else if (requestType == ClientRequest.Type.b) { final String znode; try { znode = ((TextNode) jsonRequest.get("z")).textValue(); } catch (Exception e) { return; // TODO return error } final DataMessage dataMessage = zkStateObserver.retrieveNodeData(znode); if (dataMessage != null) { writeClientMessage(ctx, dataMessage); } } else { System.out.println("unknown, unhandled client request = " + request); } } protected void writeClientMessage(ChannelHandlerContext ctx, ClientMessage clientMessage) { ctx.channel().writeAndFlush(new TextWebSocketFrame(clientMessage.toJson())); } private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) { // Generate an error page if response getStatus code is not OK (200). if (res.getStatus().code() != 200) { ByteBuf buf = Unpooled.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8); res.content().writeBytes(buf); buf.release(); setContentLength(res, res.content().readableBytes()); } // Send the response and close the connection if necessary. ChannelFuture f = ctx.channel().writeAndFlush(res); if (!isKeepAlive(req) || res.getStatus().code() != 200) { f.addListener(ChannelFutureListener.CLOSE); } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); ctx.close(); } private static String getWebSocketLocation(FullHttpRequest req) { return "ws://" + req.headers().get(HOST) + WEBSOCKET_PATH; } @Override protected void channelRead0(ChannelHandlerContext channelHandlerContext, Object o) throws Exception { messageReceived(channelHandlerContext, o); } }