模拟订阅和发送
MQTT X 是 EMQ 开源的一款优雅的跨平台 MQTT 5.0 桌面客户端，它支持 macOS, Linux, Windows。
MQTT X 的 UI 采用了聊天界面形式，简化了页面操作逻辑，用户可以快速创建连接，允许保存多个客户端，方便用户快速测试 MQTT/MQTTS 连接，及 MQTT 消息的订阅和发布。
客户端日志
LoggerFactory.setLogger(LoggerImpl.class.getName());
MqttException
/**
* Thrown if an error occurs communicating with the server.
*/
public class MqttException extends Exception {
private static final long serialVersionUID = 300L;
/**
* Client encountered an exception. Use the {@link #getCause()}
* method to get the underlying reason.
*/
public static final short REASON_CODE_CLIENT_EXCEPTION = 0x00;
// CONNACK return codes
/** The protocol version requested is not supported by the server. */
public static final short REASON_CODE_INVALID_PROTOCOL_VERSION = 0x01;
/** The server has rejected the supplied client ID */
public static final short REASON_CODE_INVALID_CLIENT_ID = 0x02;
/** The broker was not available to handle the request. */
public static final short REASON_CODE_BROKER_UNAVAILABLE = 0x03;
/** Authentication with the server has failed, due to a bad user name or password. */
public static final short REASON_CODE_FAILED_AUTHENTICATION = 0x04;
/** Not authorized to perform the requested operation */
public static final short REASON_CODE_NOT_AUTHORIZED = 0x05;
/** An unexpected error has occurred. */
public static final short REASON_CODE_UNEXPECTED_ERROR = 0x06;
/** Error from subscribe - returned from the server. */
public static final short REASON_CODE_SUBSCRIBE_FAILED = 0x80;
/**
* Client timed out while waiting for a response from the server.
* The server is no longer responding to keep-alive messages.
*/
public static final short REASON_CODE_CLIENT_TIMEOUT = 32000;
/**
* Internal error, caused by no new message IDs being available.
*/
public static final short REASON_CODE_NO_MESSAGE_IDS_AVAILABLE = 32001;
/**
* Client timed out while waiting to write messages to the server.
*/
public static final short REASON_CODE_WRITE_TIMEOUT = 32002;
/**
* The client is already connected.
*/
public static final short REASON_CODE_CLIENT_CONNECTED = 32100;
/**
* The client is already disconnected.
*/
public static final short REASON_CODE_CLIENT_ALREADY_DISCONNECTED = 32101;
/**
* The client is currently disconnecting and cannot accept any new work.
* This can occur when waiting on a token, and then disconnecting the client.
* If the message delivery does not complete within the quiesce timeout
* period, then the waiting token will be notified with an exception.
*/
public static final short REASON_CODE_CLIENT_DISCONNECTING = 32102;
/** Unable to connect to server */
public static final short REASON_CODE_SERVER_CONNECT_ERROR = 32103;
/**
* The client is not connected to the server. The {@link MqttClient#connect()}
* or {@link MqttClient#connect(MqttConnectOptions)} method must be called
* first. It is also possible that the connection was lost - see
* {@link MqttClient#setCallback(MqttCallback)} for a way to track lost
* connections.
*/
public static final short REASON_CODE_CLIENT_NOT_CONNECTED = 32104;
/**
* Server URI and supplied <code>SocketFactory</code> do not match.
* URIs beginning <code>tcp://</code> must use a <code>javax.net.SocketFactory</code>,
* and URIs beginning <code>ssl://</code> must use a <code>javax.net.ssl.SSLSocketFactory</code>.
*/
public static final short REASON_CODE_SOCKET_FACTORY_MISMATCH = 32105;
/**
* SSL configuration error.
*/
public static final short REASON_CODE_SSL_CONFIG_ERROR = 32106;
/**
* Thrown when an attempt to call {@link MqttClient#disconnect()} has been
* made from within a method on {@link MqttCallback}. These methods are invoked
* by the client's thread, and must not be used to control disconnection.
*
* @see MqttCallback#messageArrived(String, MqttMessage)
*/
public static final short REASON_CODE_CLIENT_DISCONNECT_PROHIBITED = 32107;
/**
* Protocol error: the message was not recognized as a valid MQTT packet.
* Possible reasons for this include connecting to a non-MQTT server, or
* connecting to an SSL server port when the client isn't using SSL.
*/
public static final short REASON_CODE_INVALID_MESSAGE = 32108;
/**
* The client has been unexpectedly disconnected from the server. The {@link #getCause() cause}
* will provide more details.
*/
public static final short REASON_CODE_CONNECTION_LOST = 32109;
/**
* A connect operation in already in progress, only one connect can happen
* at a time.
*/
public static final short REASON_CODE_CONNECT_IN_PROGRESS = 32110;
/**
* The client is closed - no operations are permitted on the client in this
* state. New up a new client to continue.
*/
public static final short REASON_CODE_CLIENT_CLOSED = 32111;
/**
* A request has been made to use a token that is already associated with
* another action. If the action is complete the reset() can ve called on the
* token to allow it to be reused.
*/
public static final short REASON_CODE_TOKEN_INUSE = 32201;
/**
* A request has been made to send a message but the maximum number of inflight
* messages has already been reached. Once one or more messages have been moved
* then new messages can be sent.
*/
public static final short REASON_CODE_MAX_INFLIGHT = 32202;
/**
* The Client has attempted to publish a message whilst in the 'resting' / offline
* state with Disconnected Publishing enabled, however the buffer is full and
* deleteOldestMessages is disabled, therefore no more messages can be published
* until the client reconnects, or the application deletes buffered message
* manually.
*/
public static final short REASON_CODE_DISCONNECTED_BUFFER_FULL = 32203;
}
