app.WebSocketServerHandler.java Source code

Introduction

Here is the source code for app.WebSocketServerHandler.java

Source

/*
 * Copyright 2014 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 app;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.handler.codec.http.*;
import io.netty.handler.codec.http.websocketx.*;
import io.netty.util.CharsetUtil;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;

import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;

import static io.netty.handler.codec.http.HttpMethod.GET;
import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
import static io.netty.handler.codec.http.HttpResponseStatus.FORBIDDEN;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

/**
 * Handles handshakes and messages
 */
public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {

    private static final String WEBSOCKET_PATH = "/ws";

    private WebSocketServerHandshaker handshaker;

    private static final Queue<Channel> channels = new ConcurrentLinkedQueue<>();

    @Override
    public void channelRead0(ChannelHandlerContext ctx, Object msg) {
        if (msg instanceof FullHttpRequest) {
            handleHttpRequest(ctx, (FullHttpRequest) msg);
        } else if (msg instanceof WebSocketFrame) {
            handleWebSocketFrame(ctx, (WebSocketFrame) msg);
        }
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.flush();
    }

    private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) {
        // Handle a bad request.
        if (!req.decoderResult().isSuccess()) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST));
            return;
        }

        // Allow only GET methods.
        if (req.method() != GET) {
            sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN));
            return;
        }

        // Handshake
        WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(getWebSocketLocation(req),
                null, true, 5 * 1024 * 1024);
        handshaker = wsFactory.newHandshaker(req);
        if (handshaker == null) {
            WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
        } else {
            handshaker.handshake(ctx.channel(), req);
            channels.add(ctx.channel());
        }
    }

    private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) {

        // Check for closing frame
        if (frame instanceof CloseWebSocketFrame) {
            channels.remove(ctx.channel());
            handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain());
            return;
        }
        if (frame instanceof PingWebSocketFrame) {
            ctx.write(new PongWebSocketFrame(frame.content().retain()));
            return;
        }
        if (frame instanceof TextWebSocketFrame) {
            JSONObject msg = (JSONObject) JSONValue.parse(((TextWebSocketFrame) frame).text());

            if (msg == null) {
                System.out.println("Unknown message type");
                return;
            }

            switch (msg.get("type").toString()) {
            case "broadcast":
                final TextWebSocketFrame outbound = new TextWebSocketFrame(msg.toJSONString());
                channels.forEach(gc -> gc.writeAndFlush(outbound.duplicate().retain()));
                msg.replace("type", "broadcastResult");
                ctx.writeAndFlush(new TextWebSocketFrame(msg.toJSONString()));
                break;
            case "echo":
                ctx.writeAndFlush(new TextWebSocketFrame(msg.toJSONString()));
                break;
            default:
                System.out.println("Unknown message type");
            }

            return;
        }
    }

    private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) {
        // Generate an error page if response getStatus code is not OK (200).
        if (res.status().code() != 200) {
            ByteBuf buf = Unpooled.copiedBuffer(res.status().toString(), CharsetUtil.UTF_8);
            res.content().writeBytes(buf);
            buf.release();
            HttpUtil.setContentLength(res, res.content().readableBytes());
        }

        // Send the response and close the connection if necessary.
        ChannelFuture f = ctx.channel().writeAndFlush(res);
        if (!HttpUtil.isKeepAlive(req) || res.status().code() != 200) {
            f.addListener(ChannelFutureListener.CLOSE);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        cause.printStackTrace();
        ctx.close();
    }

    private static String getWebSocketLocation(FullHttpRequest req) {
        String location = req.headers().get(HttpHeaderNames.HOST) + WEBSOCKET_PATH;
        return "ws://" + location;
    }
}