import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
/**
 * Constructor specifying the destination web socket location
 *
 * @param version
 *            the protocol version
 * @param uri
 *            URL for web socket communications. e.g "ws://myhost.com/mypath". Subsequent web socket frames will be
 *            sent to this URL.
 * @param subprotocols
 *            CSV of supported protocols. Null if sub protocols not supported.
 * @param maxFramePayloadLength
 *            Maximum length of a frame's payload
 */
protected WebSocketServerHandshaker(
        WebSocketVersion version, String uri, String subprotocols,
        int maxFramePayloadLength) {
    this.version = version;
    this.uri = uri;
    if (subprotocols != null) {
        String[] subprotocolArray = StringUtil.split(subprotocols, ',');
        for (int i = 0; i < subprotocolArray.length; i++) {
            subprotocolArray[i] = subprotocolArray[i].trim();
        }
        this.subprotocols = subprotocolArray;
    } else {
        this.subprotocols = EmptyArrays.EMPTY_STRINGS;
    }
    this.maxFramePayloadLength = maxFramePayloadLength;
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
/**
 * Create a new {@link ThreadPerChannelEventLoopGroup}.
 *
 * @param maxChannels       the maximum number of channels to handle with this instance. Once you try to register
 *                          a new {@link Channel} and the maximum is exceed it will throw an
 *                          {@link ChannelException} on the {@link #register(Channel)} and
 *                          {@link #register(Channel, ChannelPromise)} method.
 *                          Use {@code 0} to use no limit
 * @param threadFactory     the {@link ThreadFactory} used to create new {@link Thread} instances that handle the
 *                          registered {@link Channel}s
 * @param args              arguments which will passed to each {@link #newChild(Object...)} call.
 */
protected ThreadPerChannelEventLoopGroup(int maxChannels, ThreadFactory threadFactory, Object... args) {
    if (maxChannels < 0) {
        throw new IllegalArgumentException(String.format(
                "maxChannels: %d (expected: >= 0)", maxChannels));
    }
    if (threadFactory == null) {
        throw new NullPointerException("threadFactory");
    }

    if (args == null) {
        childArgs = EmptyArrays.EMPTY_OBJECTS;
    } else {
        childArgs = args.clone();
    }

    this.maxChannels = maxChannels;
    this.threadFactory = threadFactory;

    tooManyChannels = new ChannelException("too many channels (max: " + maxChannels + ')');
    tooManyChannels.setStackTrace(EmptyArrays.EMPTY_STACK_TRACE);
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
/**
 * Create a new {@link ThreadPerChannelEventLoopGroup}.
 *
 * @param maxChannels       the maximum number of channels to handle with this instance. Once you try to register
 *                          a new {@link Channel} and the maximum is exceed it will throw an
 *                          {@link ChannelException}. Use {@code 0} to use no limit
 * @param executor          the {@link Executor} used to create new {@link Thread} instances that handle the
 *                          registered {@link Channel}s
 * @param args              arguments which will passed to each {@link #newChild(Object...)} call.
 */
protected ThreadPerChannelEventLoopGroup(int maxChannels, Executor executor, Object... args) {
    if (maxChannels < 0) {
        throw new IllegalArgumentException(String.format(
                "maxChannels: %d (expected: >= 0)", maxChannels));
    }
    if (executor == null) {
        throw new NullPointerException("executor");
    }

    if (args == null) {
        childArgs = EmptyArrays.EMPTY_OBJECTS;
    } else {
        childArgs = args.clone();
    }

    this.maxChannels = maxChannels;
    this.executor = executor;

    tooManyChannels = new ChannelException("too many channels (max: " + maxChannels + ')');
    tooManyChannels.setStackTrace(EmptyArrays.EMPTY_STACK_TRACE);
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public byte[] get() throws IOException {
    if (file == null) {
        return EmptyArrays.EMPTY_BYTES;
    }
    return readFrom(file);
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
private static ByteBuf newBinaryData(int statusCode, String reasonText) {
    byte[] reasonBytes = EmptyArrays.EMPTY_BYTES;
    if (reasonText != null) {
        reasonBytes = reasonText.getBytes(CharsetUtil.UTF_8);
    }

    ByteBuf binaryData = Unpooled.buffer(2 + reasonBytes.length);
    binaryData.writeShort(statusCode);
    if (reasonBytes.length > 0) {
        binaryData.writeBytes(reasonBytes);
    }

    binaryData.readerIndex(0);
    return binaryData;
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public String[] getEnabledCipherSuites() {
    String[] enabled = SSL.getCiphers(ssl);
    if (enabled == null) {
        return EmptyArrays.EMPTY_STRINGS;
    } else {
        for (int i = 0; i < enabled.length; i++) {
            String mapped = toJavaCipherSuite(enabled[i]);
            if (mapped != null) {
                enabled[i] = mapped;
            }
        }
        return enabled;
    }
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public String[] getEnabledProtocols() {
    List<String> enabled = new ArrayList<String>();
    // Seems like there is no way to explict disable SSLv2Hello in openssl so it is always enabled
    enabled.add(PROTOCOL_SSL_V2_HELLO);
    int opts = SSL.getOptions(ssl);
    if ((opts & SSL.SSL_OP_NO_TLSv1) == 0) {
        enabled.add(PROTOCOL_TLS_V1);
    }
    if ((opts & SSL.SSL_OP_NO_TLSv1_1) == 0) {
        enabled.add(PROTOCOL_TLS_V1_1);
    }
    if ((opts & SSL.SSL_OP_NO_TLSv1_2) == 0) {
        enabled.add(PROTOCOL_TLS_V1_2);
    }
    if ((opts & SSL.SSL_OP_NO_SSLv2) == 0) {
        enabled.add(PROTOCOL_SSL_V2);
    }
    if ((opts & SSL.SSL_OP_NO_SSLv3) == 0) {
        enabled.add(PROTOCOL_SSL_V3);
    }
    int size = enabled.size();
    if (size == 0) {
        return EmptyArrays.EMPTY_STRINGS;
    } else {
        return enabled.toArray(new String[size]);
    }
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public String[] getValueNames() {
    Map<String, Object> values = this.values;
    if (values == null || values.isEmpty()) {
        return EmptyArrays.EMPTY_STRINGS;
    }
    return values.keySet().toArray(new String[values.size()]);
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public byte[] array() {
    switch (components.size()) {
    case 0:
        return EmptyArrays.EMPTY_BYTES;
    case 1:
        return components.get(0).buf.array();
    default:
        throw new UnsupportedOperationException();
    }
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public int setBytes(int index, InputStream in, int length) throws IOException {
    checkIndex(index, length);
    if (length == 0) {
        return in.read(EmptyArrays.EMPTY_BYTES);
    }

    int i = toComponentIndex(index);
    int readBytes = 0;

    do {
        Component c = components.get(i);
        ByteBuf s = c.buf;
        int adjustment = c.offset;
        int localLength = Math.min(length, s.capacity() - (index - adjustment));
        int localReadBytes = s.setBytes(index - adjustment, in, localLength);
        if (localReadBytes < 0) {
            if (readBytes == 0) {
                return -1;
            } else {
                break;
            }
        }

        if (localReadBytes == localLength) {
            index += localLength;
            length -= localLength;
            readBytes += localLength;
            i ++;
        } else {
            index += localReadBytes;
            length -= localReadBytes;
            readBytes += localReadBytes;
        }
    } while (length > 0);

    return readBytes;
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Test
public void testGZIPCompressOnly() throws Exception {
    testGZIPCompressOnly0(null); // Do not write anything; just finish the stream.
    testGZIPCompressOnly0(EmptyArrays.EMPTY_BYTES); // Write an empty array.
    testGZIPCompressOnly0(BYTES_SMALL);
    testGZIPCompressOnly0(BYTES_LARGE);
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public ByteBuffer[] nioBuffers(int index, int length) {
    checkIndex(index, length);
    if (length == 0) {
        return EmptyArrays.EMPTY_BYTE_BUFFERS;
    }

    List<ByteBuffer> buffers = new ArrayList<ByteBuffer>(components.size());
    int i = toComponentIndex(index);
    while (length > 0) {
        Component c = components.get(i);
        ByteBuf s = c.buf;
        int adjustment = c.offset;
        int localLength = Math.min(length, s.capacity() - (index - adjustment));
        switch (s.nioBufferCount()) {
            case 0:
                throw new UnsupportedOperationException();
            case 1:
                buffers.add(s.nioBuffer(index - adjustment, localLength));
                break;
            default:
                Collections.addAll(buffers, s.nioBuffers(index - adjustment, localLength));
        }

        index += localLength;
        length -= localLength;
        i ++;
    }

    return buffers.toArray(new ByteBuffer[buffers.size()]);
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public ByteBuffer[] nioBuffers(int index, int length) {
    checkIndex(index, length);
    if (length == 0) {
        return EmptyArrays.EMPTY_BYTE_BUFFERS;
    }

    RecyclableArrayList array = RecyclableArrayList.newInstance(buffers.length);
    try {
        Component c = findComponent(index);
        int i = c.index;
        int adjustment = c.offset;
        ByteBuf s = c.buf;
        for (;;) {
            int localLength = Math.min(length, s.capacity() - (index - adjustment));
            switch (s.nioBufferCount()) {
                case 0:
                    throw new UnsupportedOperationException();
                case 1:
                    array.add(s.nioBuffer(index - adjustment, localLength));
                    break;
                default:
                    Collections.addAll(array, s.nioBuffers(index - adjustment, localLength));
            }

            index += localLength;
            length -= localLength;
            adjustment += s.readableBytes();
            if (length <= 0) {
                break;
            }
            s = buffer(++i);
        }

        return array.toArray(new ByteBuffer[array.size()]);
    } finally {
        array.recycle();
    }
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
private static ByteBuf encodeConnectMessage(
        ByteBufAllocator byteBufAllocator,
        MqttConnectMessage message) {
    int payloadBufferSize = 0;

    MqttFixedHeader mqttFixedHeader = message.fixedHeader();
    MqttConnectVariableHeader variableHeader = message.variableHeader();
    MqttConnectPayload payload = message.payload();
    MqttVersion mqttVersion = MqttVersion.fromProtocolNameAndLevel(variableHeader.name(),
            (byte) variableHeader.version());

    // Client id
    String clientIdentifier = payload.clientIdentifier();
    if (!isValidClientId(mqttVersion, clientIdentifier)) {
        throw new MqttIdentifierRejectedException("invalid clientIdentifier: " + clientIdentifier);
    }
    byte[] clientIdentifierBytes = encodeStringUtf8(clientIdentifier);
    payloadBufferSize += 2 + clientIdentifierBytes.length;

    // Will topic and message
    String willTopic = payload.willTopic();
    byte[] willTopicBytes = willTopic != null ? encodeStringUtf8(willTopic) : EmptyArrays.EMPTY_BYTES;
    byte[] willMessage = payload.willMessageInBytes();
    byte[] willMessageBytes = willMessage != null ? willMessage : EmptyArrays.EMPTY_BYTES;
    if (variableHeader.isWillFlag()) {
        payloadBufferSize += 2 + willTopicBytes.length;
        payloadBufferSize += 2 + willMessageBytes.length;
    }

    String userName = payload.userName();
    byte[] userNameBytes = userName != null ? encodeStringUtf8(userName) : EmptyArrays.EMPTY_BYTES;
    if (variableHeader.hasUserName()) {
        payloadBufferSize += 2 + userNameBytes.length;
    }

    byte[] password = payload.passwordInBytes();
    byte[] passwordBytes = password != null ? password : EmptyArrays.EMPTY_BYTES;
    if (variableHeader.hasPassword()) {
        payloadBufferSize += 2 + passwordBytes.length;
    }

    // Fixed header
    byte[] protocolNameBytes = mqttVersion.protocolNameBytes();
    int variableHeaderBufferSize = 2 + protocolNameBytes.length + 4;
    int variablePartSize = variableHeaderBufferSize + payloadBufferSize;
    int fixedHeaderBufferSize = 1 + getVariableLengthInt(variablePartSize);
    ByteBuf buf = byteBufAllocator.buffer(fixedHeaderBufferSize + variablePartSize);
    buf.writeByte(getFixedHeaderByte1(mqttFixedHeader));
    writeVariableLengthInt(buf, variablePartSize);

    buf.writeShort(protocolNameBytes.length);
    buf.writeBytes(protocolNameBytes);

    buf.writeByte(variableHeader.version());
    buf.writeByte(getConnVariableHeaderFlag(variableHeader));
    buf.writeShort(variableHeader.keepAliveTimeSeconds());

    // Payload
    buf.writeShort(clientIdentifierBytes.length);
    buf.writeBytes(clientIdentifierBytes, 0, clientIdentifierBytes.length);
    if (variableHeader.isWillFlag()) {
        buf.writeShort(willTopicBytes.length);
        buf.writeBytes(willTopicBytes, 0, willTopicBytes.length);
        buf.writeShort(willMessageBytes.length);
        buf.writeBytes(willMessageBytes, 0, willMessageBytes.length);
    }
    if (variableHeader.hasUserName()) {
        buf.writeShort(userNameBytes.length);
        buf.writeBytes(userNameBytes, 0, userNameBytes.length);
    }
    if (variableHeader.hasPassword()) {
        buf.writeShort(passwordBytes.length);
        buf.writeBytes(passwordBytes, 0, passwordBytes.length);
    }
    return buf;
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public X509Certificate[] getAcceptedIssuers() {
    return EmptyArrays.EMPTY_X509_CERTIFICATES;
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Override
public byte[] array() {
    return EmptyArrays.EMPTY_BYTES;
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
private ChannelFuture finishEncode(ChannelHandlerContext ctx, ChannelPromise promise) {
    if (finished) {
        promise.setSuccess();
        return promise;
    }
    finished = true;

    ByteBuf footer;
    try {
        // Configure input.
        z.next_in = EmptyArrays.EMPTY_BYTES;
        z.next_in_index = 0;
        z.avail_in = 0;

        // Configure output.
        byte[] out = new byte[32]; // room for ADLER32 + ZLIB / CRC32 + GZIP header
        z.next_out = out;
        z.next_out_index = 0;
        z.avail_out = out.length;

        // Write the ADLER32 checksum (stream footer).
        int resultCode = z.deflate(JZlib.Z_FINISH);
        if (resultCode != JZlib.Z_OK && resultCode != JZlib.Z_STREAM_END) {
            promise.setFailure(ZlibUtil.deflaterException(z, "compression failure", resultCode));
            return promise;
        } else if (z.next_out_index != 0) {
            footer = Unpooled.wrappedBuffer(out, 0, z.next_out_index);
        } else {
            footer = Unpooled.EMPTY_BUFFER;
        }
    } finally {
        z.deflateEnd();

        // Deference the external references explicitly to tell the VM that
        // the allocated byte arrays are temporary so that the call stack
        // can be utilized.
        // I'm not sure if the modern VMs do this optimization though.
        z.next_in = null;
        z.next_out = null;
    }
    return ctx.writeAndFlush(footer, promise);
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Test
public void testDecodeEmpty() {
    ch.writeInbound(EMPTY_BUFFER);
    assertThat((byte[]) ch.readInbound(), is(EmptyArrays.EMPTY_BYTES));
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
@Test
public void testEncodeEmpty() {
    ch.writeOutbound(EmptyArrays.EMPTY_BYTES);
    assertThat((ByteBuf) ch.readOutbound(), is(sameInstance(EMPTY_BUFFER)));
}
 

import io.netty.util.internal.EmptyArrays; //导入依赖的package包/类
private static IOException newConnectionResetException(String method, int errnoNegative) {
    IOException exception = newIOException(method, errnoNegative);
    exception.setStackTrace(EmptyArrays.EMPTY_STACK_TRACE);
    return exception;
}