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Java example source code file (WebSocket08FrameEncoder.java)

This example Java source code file (WebSocket08FrameEncoder.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytebuf, byteorder, encoding, gathering_write_threshold, internallogger, nio, opcode_binary, opcode_close, opcode_cont, opcode_ping, opcode_pong, opcode_text, pingwebsocketframe, pongwebsocketframe, util, websocket08frameencoder

The WebSocket08FrameEncoder.java Java example source code

/*
 * 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.
 */
// (BSD License: http://www.opensource.org/licenses/bsd-license)
//
// Copyright (c) 2011, Joe Walnes and contributors
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or
// without modification, are permitted provided that the
// following conditions are met:
//
// * Redistributions of source code must retain the above
// copyright notice, this list of conditions and the
// following disclaimer.
//
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the
// following disclaimer in the documentation and/or other
// materials provided with the distribution.
//
// * Neither the name of the Webbit nor the names of
// its contributors may be used to endorse or promote products
// derived from this software without specific prior written
// permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
// CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

package io.netty.handler.codec.http.websocketx;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageEncoder;
import io.netty.handler.codec.TooLongFrameException;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.List;

/**
 * <p>
 * Encodes a web socket frame into wire protocol version 8 format. This code was forked from <a
 * href="https://github.com/joewalnes/webbit">webbit</a> and modified.
 * </p>
 */
public class WebSocket08FrameEncoder extends MessageToMessageEncoder<WebSocketFrame> implements WebSocketFrameEncoder {

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(WebSocket08FrameEncoder.class);

    private static final byte OPCODE_CONT = 0x0;
    private static final byte OPCODE_TEXT = 0x1;
    private static final byte OPCODE_BINARY = 0x2;
    private static final byte OPCODE_CLOSE = 0x8;
    private static final byte OPCODE_PING = 0x9;
    private static final byte OPCODE_PONG = 0xA;

    /**
     * The size threshold for gathering writes. Non-Masked messages bigger than this size will be be sent fragmented as
     * a header and a content ByteBuf whereas messages smaller than the size will be merged into a single buffer and
     * sent at once.<br>
     * Masked messages will always be sent at once.
     */
    private static final int GATHERING_WRITE_THRESHOLD = 1024;

    private final boolean maskPayload;

    /**
     * Constructor
     *
     * @param maskPayload
     *            Web socket clients must set this to true to mask payload. Server implementations must set this to
     *            false.
     */
    public WebSocket08FrameEncoder(boolean maskPayload) {
        this.maskPayload = maskPayload;
    }

    @Override
    protected void encode(ChannelHandlerContext ctx, WebSocketFrame msg, List<Object> out) throws Exception {
        final ByteBuf data = msg.content();
        byte[] mask;

        byte opcode;
        if (msg instanceof TextWebSocketFrame) {
            opcode = OPCODE_TEXT;
        } else if (msg instanceof PingWebSocketFrame) {
            opcode = OPCODE_PING;
        } else if (msg instanceof PongWebSocketFrame) {
            opcode = OPCODE_PONG;
        } else if (msg instanceof CloseWebSocketFrame) {
            opcode = OPCODE_CLOSE;
        } else if (msg instanceof BinaryWebSocketFrame) {
            opcode = OPCODE_BINARY;
        } else if (msg instanceof ContinuationWebSocketFrame) {
            opcode = OPCODE_CONT;
        } else {
            throw new UnsupportedOperationException("Cannot encode frame of type: " + msg.getClass().getName());
        }

        int length = data.readableBytes();

        if (logger.isDebugEnabled()) {
            logger.debug("Encoding WebSocket Frame opCode=" + opcode + " length=" + length);
        }

        int b0 = 0;
        if (msg.isFinalFragment()) {
            b0 |= 1 << 7;
        }
        b0 |= msg.rsv() % 8 << 4;
        b0 |= opcode % 128;

        if (opcode == OPCODE_PING && length > 125) {
            throw new TooLongFrameException("invalid payload for PING (payload length must be <= 125, was "
                    + length);
        }

        boolean release = true;
        ByteBuf buf = null;
        try {
            int maskLength = maskPayload ? 4 : 0;
            if (length <= 125) {
                int size = 2 + maskLength;
                if (maskPayload || length <= GATHERING_WRITE_THRESHOLD) {
                    size += length;
                }
                buf = ctx.alloc().buffer(size);
                buf.writeByte(b0);
                byte b = (byte) (maskPayload ? 0x80 | (byte) length : (byte) length);
                buf.writeByte(b);
            } else if (length <= 0xFFFF) {
                int size = 4 + maskLength;
                if (maskPayload || length <= GATHERING_WRITE_THRESHOLD) {
                    size += length;
                }
                buf = ctx.alloc().buffer(size);
                buf.writeByte(b0);
                buf.writeByte(maskPayload ? 0xFE : 126);
                buf.writeByte(length >>> 8 & 0xFF);
                buf.writeByte(length & 0xFF);
            } else {
                int size = 10 + maskLength;
                if (maskPayload || length <= GATHERING_WRITE_THRESHOLD) {
                    size += length;
                }
                buf = ctx.alloc().buffer(size);
                buf.writeByte(b0);
                buf.writeByte(maskPayload ? 0xFF : 127);
                buf.writeLong(length);
            }

            // Write payload
            if (maskPayload) {
                int random = (int) (Math.random() * Integer.MAX_VALUE);
                mask = ByteBuffer.allocate(4).putInt(random).array();
                buf.writeBytes(mask);

                ByteOrder srcOrder = data.order();
                ByteOrder dstOrder = buf.order();

                int counter = 0;
                int i = data.readerIndex();
                int end = data.writerIndex();

                if (srcOrder == dstOrder) {
                    // Use the optimized path only when byte orders match
                    // Remark: & 0xFF is necessary because Java will do signed expansion from
                    // byte to int which we don't want.
                    int intMask = ((mask[0] & 0xFF) << 24)
                                | ((mask[1] & 0xFF) << 16)
                                | ((mask[2] & 0xFF) << 8)
                                | (mask[3] & 0xFF);

                    // If the byte order of our buffers it little endian we have to bring our mask
                    // into the same format, because getInt() and writeInt() will use a reversed byte order
                    if (srcOrder == ByteOrder.LITTLE_ENDIAN) {
                        intMask = Integer.reverseBytes(intMask);
                    }

                    for (; i + 3 < end; i += 4) {
                        int intData = data.getInt(i);
                        buf.writeInt(intData ^ intMask);
                    }
                }
                for (; i < end; i++) {
                    byte byteData = data.getByte(i);
                    buf.writeByte(byteData ^ mask[counter++ % 4]);
                }
                out.add(buf);
            } else {
                if (buf.writableBytes() >= data.readableBytes()) {
                    // merge buffers as this is cheaper then a gathering write if the payload is small enough
                    buf.writeBytes(data);
                    out.add(buf);
                } else {
                    out.add(buf);
                    out.add(data.retain());
                }
            }
            release = false;
        } finally {
            if (release && buf != null) {
                buf.release();
            }
        }
    }
}

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