io.netty.util.internal.EmptyArrays#EMPTY_BYTES源码实例Demo

@Override
public byte[] get() throws IOException {
    if (file == null) {
        return EmptyArrays.EMPTY_BYTES;
    }
    return readFrom(file);
}
 

@Override
public byte[] getId() {
    synchronized (ReferenceCountedOpenSslEngine.this) {
        if (id == null) {
            return EmptyArrays.EMPTY_BYTES;
        }
        return id.clone();
    }
}
 

@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();
    }
}
 

@Override
protected void deallocate() {
    freeArray(array);
    array = EmptyArrays.EMPTY_BYTES;
    parent = null;
    offset = 0;
    RECYCLER.recycleInstance(this);
}
 

@Override
public byte[] get() throws IOException {
    if (file == null) {
        return EmptyArrays.EMPTY_BYTES;
    }
    return readFrom(file);
}
 

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;
}
 

@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();
    }
}
 

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());

    // as MQTT 3.1 & 3.1.1 spec, If the User Name Flag is set to 0, the Password Flag MUST be set to 0
    if (!variableHeader.hasUserName() && variableHeader.hasPassword()) {
        throw new DecoderException("Without a username, the password MUST be not set");
    }

    // 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;
}
 

@Override
public byte[] array() {
    return EmptyArrays.EMPTY_BYTES;
}
 

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);
}
 

private ReadOnlyPooledHeapByteBuf() {
    super(0);
    this.array = EmptyArrays.EMPTY_BYTES;
    this.offset = 0;
}
 

@Override
public byte[] array() {
    return EmptyArrays.EMPTY_BYTES;
}
 

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);
}
 

@VisibleForTesting
void clear() {
    byteArray = EmptyArrays.EMPTY_BYTES;
    stringBuilder = inflate(new StringBuilder());
    charArray = EmptyArrays.EMPTY_CHARS;
}
 

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.protocolName(),
            (byte) variableHeader.protocolLevel());

    // Client id
    String clientId = payload.clientId();
    byte[] clientIdBytes = encodeStringUtf8(clientId);
    payloadBufferSize += 2 + clientIdBytes.length;

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

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

    String password = payload.password();
    byte[] passwordBytes = password != null ? encodeStringUtf8(password) : EmptyArrays.EMPTY_BYTES;
    if (variableHeader.passwordFlag()) {
        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.protocolLevel());
    buf.writeByte(getConnVariableHeaderFlag(variableHeader));
    buf.writeShort(variableHeader.keepAlive());

    // Payload
    buf.writeShort(clientIdBytes.length);
    buf.writeBytes(clientIdBytes, 0, clientIdBytes.length);
    if (variableHeader.willFlag()) {
        buf.writeShort(willTopicBytes.length);
        buf.writeBytes(willTopicBytes, 0, willTopicBytes.length);
        buf.writeShort(willMessageBytes.length);
        buf.writeBytes(willMessageBytes, 0, willMessageBytes.length);
    }
    if (variableHeader.userNameFlag()) {
        buf.writeShort(userNameBytes.length);
        buf.writeBytes(userNameBytes, 0, userNameBytes.length);
    }
    if (variableHeader.passwordFlag()) {
        buf.writeShort(passwordBytes.length);
        buf.writeBytes(passwordBytes, 0, passwordBytes.length);
    }

    return buf;
}