1.本例子意在用moquette服务器来作为消息转发，通过订阅者订阅消息，发布者发布消息，然后发布者的消息可以通过服务器转发给订阅者
服务器例子：
https://github.com/andsel/moquette
核心代码为：
/*
* Copyright (c) 2012-2015 The original author or authors
* ------------------------------------------------------
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Apache License v2.0 which accompanies this distribution.
*
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* The Apache License v2.0 is available at
* http://www.opensource.org/licenses/apache2.0.php
*
* You may elect to redistribute this code under either of these licenses.
*/
package io.moquette.testembedded; import io.moquette.interception.AbstractInterceptHandler;
import io.moquette.interception.InterceptHandler;
import io.moquette.interception.messages.*;
import io.moquette.parser.proto.messages.AbstractMessage;
import io.moquette.parser.proto.messages.PublishMessage;
import io.moquette.server.Server;
import io.moquette.server.config.IConfig;
import io.moquette.server.config.ClasspathConfig; import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.List; import static java.util.Arrays.asList; public class EmbeddedLauncher {
static class PublisherListener extends AbstractInterceptHandler { @Override
public void onPublish(InterceptPublishMessage msg) {
System.out.println("Received on topic: " + msg.getTopicName() + " content: " + new String(msg.getPayload().array()));
}
} public static void main(String[] args) throws InterruptedException, IOException {
final IConfig classPathConfig = new ClasspathConfig(); final Server mqttBroker = new Server();
List<? extends InterceptHandler> userHandlers = asList(new PublisherListener());
mqttBroker.startServer(classPathConfig, userHandlers); System.out.println("Broker started press [CTRL+C] to stop");
//Bind a shutdown hook
Runtime.getRuntime().addShutdownHook(new Thread() {
@Override
public void run() {
System.out.println("Stopping broker");
mqttBroker.stopServer();
System.out.println("Broker stopped");
}
}); Thread.sleep(20000);
System.out.println("Before self publish");
PublishMessage message = new PublishMessage();
message.setTopicName("/exit");
message.setRetainFlag(true);
// message.setQos(AbstractMessage.QOSType.MOST_ONE);
// message.setQos(AbstractMessage.QOSType.LEAST_ONE);
message.setQos(AbstractMessage.QOSType.EXACTLY_ONCE);
message.setPayload(ByteBuffer.wrap("Hello World!!".getBytes()));
mqttBroker.internalPublish(message);
System.out.println("After self publish");
}
}
配置文件：
##############################################
# Moquette configuration file.
#
# The synthax is equals to mosquitto.conf
#
############################################## port 1883 #websocket_port 8080 host 127.0.0.1 #Password file
password_file password_file.conf #ssl_port 8883
#jks_path serverkeystore.jks
#key_store_password passw0rdsrv
#key_manager_password passw0rdsrv allow_anonymous true
配置端口为1883，而ip为127.0.0.1
启动服务器：
效果为：
2.客户端源码
https://github.com/eclipse/paho.mqtt.java
核心代码：
1）订阅者源码
/*******************************************************************************
* Copyright (c) 2009, 2014 IBM Corp.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
*
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Dave Locke - initial API and implementation and/or initial documentation
*/ package org.eclipse.paho.sample.mqttv3app; import java.io.IOException;
import java.sql.Timestamp; import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttClient;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
import org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence; /**
* A sample application that demonstrates how to use the Paho MQTT v3.1 Client blocking API.
*
* It can be run from the command line in one of two modes:
* - as a publisher, sending a single message to a topic on the server
* - as a subscriber, listening for messages from the server
*
* There are three versions of the sample that implement the same features
* but do so using using different programming styles:
* <ol>
* <li>Sample (this one) which uses the API which blocks until the operation completes</li>
* <li>SampleAsyncWait shows how to use the asynchronous API with waiters that block until
* an action completes</li>
* <li>SampleAsyncCallBack shows how to use the asynchronous API where events are
* used to notify the application when an action completes<li>
* </ol>
*
* If the application is run with the -h parameter then info is displayed that
* describes all of the options / parameters.
*/
public class Sample implements MqttCallback { /**
* The main entry point of the sample.
*
* This method handles parsing of the arguments specified on the
* command-line before performing the specified action.
*/
public static void main(String[] args) { // Default settings:
boolean quietMode = false;
String action = "subscribe";
String topic = "";
String message = "this is a subscriber,to subscribe message";
int qos = 2;
String broker = "127.0.0.1";
int port = 1883;
String clientId = null;
String subTopic = "Sample/#";
String pubTopic = "Sample/Java/v3";
boolean cleanSession = true; // Non durable subscriptions
boolean ssl = false;
String password = null;
String userName = null;
// Parse the arguments -
for (int i=0; i<args.length; i++) {
// Check this is a valid argument
if (args[i].length() == 2 && args[i].startsWith("-")) {
char arg = args[i].charAt(1);
// Handle arguments that take no-value
switch(arg) {
case 'h': case '?': printHelp(); return;
case 'q': quietMode = true; continue;
} // Now handle the arguments that take a value and
// ensure one is specified
if (i == args.length -1 || args[i+1].charAt(0) == '-') {
System.out.println("Missing value for argument: "+args[i]);
printHelp();
return;
}
switch(arg) {
case 'a': action = args[++i]; break;
case 't': topic = args[++i]; break;
case 'm': message = args[++i]; break;
case 's': qos = Integer.parseInt(args[++i]); break;
case 'b': broker = args[++i]; break;
case 'p': port = Integer.parseInt(args[++i]); break;
case 'i': clientId = args[++i]; break;
case 'c': cleanSession = Boolean.valueOf(args[++i]).booleanValue(); break;
case 'k': System.getProperties().put("javax.net.ssl.keyStore", args[++i]); break;
case 'w': System.getProperties().put("javax.net.ssl.keyStorePassword", args[++i]); break;
case 'r': System.getProperties().put("javax.net.ssl.trustStore", args[++i]); break;
case 'v': ssl = Boolean.valueOf(args[++i]).booleanValue(); break;
case 'u': userName = args[++i]; break;
case 'z': password = args[++i]; break;
default:
System.out.println("Unrecognised argument: "+args[i]);
printHelp();
return;
}
} else {
System.out.println("Unrecognised argument: "+args[i]);
printHelp();
return;
}
} // Validate the provided arguments
if (!action.equals("publish") && !action.equals("subscribe")) {
System.out.println("Invalid action: "+action);
printHelp();
return;
}
if (qos < 0 || qos > 2) {
System.out.println("Invalid QoS: "+qos);
printHelp();
return;
}
if (topic.equals("")) {
// Set the default topic according to the specified action
if (action.equals("publish")) {
topic = pubTopic;
} else {
topic = subTopic;
}
} String protocol = "tcp://"; if (ssl) {
protocol = "ssl://";
} String url = protocol + broker + ":" + port; if (clientId == null || clientId.equals("")) {
clientId = "SampleJavaV3_"+action;
} // With a valid set of arguments, the real work of
// driving the client API can begin
try {
// Create an instance of this class
Sample sampleClient = new Sample(url, clientId, cleanSession, quietMode,userName,password); // Perform the requested action
if (action.equals("publish")) {
sampleClient.publish(topic,qos,message.getBytes());
} else if (action.equals("subscribe")) {
sampleClient.subscribe(topic,qos);
}
} catch(MqttException me) {
// Display full details of any exception that occurs
System.out.println("reason "+me.getReasonCode());
System.out.println("msg "+me.getMessage());
System.out.println("loc "+me.getLocalizedMessage());
System.out.println("cause "+me.getCause());
System.out.println("excep "+me);
me.printStackTrace();
}
} // Private instance variables
private MqttClient client;
private String brokerUrl;
private boolean quietMode;
private MqttConnectOptions conOpt;
private boolean clean;
private String password;
private String userName; /**
* Constructs an instance of the sample client wrapper
* @param brokerUrl the url of the server to connect to
* @param clientId the client id to connect with
* @param cleanSession clear state at end of connection or not (durable or non-durable subscriptions)
* @param quietMode whether debug should be printed to standard out
* @param userName the username to connect with
* @param password the password for the user
* @throws MqttException
*/
public Sample(String brokerUrl, String clientId, boolean cleanSession, boolean quietMode, String userName, String password) throws MqttException {
this.brokerUrl = brokerUrl;
this.quietMode = quietMode;
this.clean = cleanSession;
this.password = password;
this.userName = userName;
//This sample stores in a temporary directory... where messages temporarily
// stored until the message has been delivered to the server.
//..a real application ought to store them somewhere
// where they are not likely to get deleted or tampered with
String tmpDir = System.getProperty("java.io.tmpdir");
MqttDefaultFilePersistence dataStore = new MqttDefaultFilePersistence(tmpDir); try {
// Construct the connection options object that contains connection parameters
// such as cleanSession and LWT
conOpt = new MqttConnectOptions();
conOpt.setCleanSession(clean);
if(password != null ) {
conOpt.setPassword(this.password.toCharArray());
}
if(userName != null) {
conOpt.setUserName(this.userName);
} // Construct an MQTT blocking mode client
client = new MqttClient(this.brokerUrl,clientId, dataStore); // Set this wrapper as the callback handler
client.setCallback(this); } catch (MqttException e) {
e.printStackTrace();
log("Unable to set up client: "+e.toString());
System.exit(1);
}
} /**
* Publish / send a message to an MQTT server
* @param topicName the name of the topic to publish to
* @param qos the quality of service to delivery the message at (0,1,2)
* @param payload the set of bytes to send to the MQTT server
* @throws MqttException
*/
public void publish(String topicName, int qos, byte[] payload) throws MqttException { // Connect to the MQTT server
log("Connecting to "+brokerUrl + " with client ID "+client.getClientId());
client.connect(conOpt);
log("Connected"); String time = new Timestamp(System.currentTimeMillis()).toString();
log("Publishing at: "+time+ " to topic \""+topicName+"\" qos "+qos); // Create and configure a message
MqttMessage message = new MqttMessage(payload);
message.setQos(qos); // Send the message to the server, control is not returned until
// it has been delivered to the server meeting the specified
// quality of service.
client.publish(topicName, message); // Disconnect the client
client.disconnect();
log("Disconnected");
} /**
* Subscribe to a topic on an MQTT server
* Once subscribed this method waits for the messages to arrive from the server
* that match the subscription. It continues listening for messages until the enter key is
* pressed.
* @param topicName to subscribe to (can be wild carded)
* @param qos the maximum quality of service to receive messages at for this subscription
* @throws MqttException
*/
public void subscribe(String topicName, int qos) throws MqttException { // Connect to the MQTT server
client.connect(conOpt);
log("Connected to "+brokerUrl+" with client ID "+client.getClientId()); // Subscribe to the requested topic
// The QoS specified is the maximum level that messages will be sent to the client at.
// For instance if QoS 1 is specified, any messages originally published at QoS 2 will
// be downgraded to 1 when delivering to the client but messages published at 1 and 0
// will be received at the same level they were published at.
log("Subscribing to topic \""+topicName+"\" qos "+qos);
client.subscribe(topicName, qos); // Continue waiting for messages until the Enter is pressed
log("Press <Enter> to exit");
try {
System.in.read();
} catch (IOException e) {
//If we can't read we'll just exit
} // Disconnect the client from the server
client.disconnect();
log("Disconnected");
} /**
* Utility method to handle logging. If 'quietMode' is set, this method does nothing
* @param message the message to log
*/
private void log(String message) {
if (!quietMode) {
System.out.println(message);
}
} /****************************************************************/
/* Methods to implement the MqttCallback interface */
/****************************************************************/ /**
* @see MqttCallback#connectionLost(Throwable)
*/
public void connectionLost(Throwable cause) {
// Called when the connection to the server has been lost.
// An application may choose to implement reconnection
// logic at this point. This sample simply exits.
log("Connection to " + brokerUrl + " lost!" + cause);
System.exit(1);
} /**
* @see MqttCallback#deliveryComplete(IMqttDeliveryToken)
*/
public void deliveryComplete(IMqttDeliveryToken token) {
// Called when a message has been delivered to the
// server. The token passed in here is the same one
// that was passed to or returned from the original call to publish.
// This allows applications to perform asynchronous
// delivery without blocking until delivery completes.
//
// This sample demonstrates asynchronous deliver and
// uses the token.waitForCompletion() call in the main thread which
// blocks until the delivery has completed.
// Additionally the deliveryComplete method will be called if
// the callback is set on the client
//
// If the connection to the server breaks before delivery has completed
// delivery of a message will complete after the client has re-connected.
// The getPendingTokens method will provide tokens for any messages
// that are still to be delivered.
} /**
* @see MqttCallback#messageArrived(String, MqttMessage)
*/
public void messageArrived(String topic, MqttMessage message) throws MqttException {
// Called when a message arrives from the server that matches any
// subscription made by the client
String time = new Timestamp(System.currentTimeMillis()).toString();
System.out.println("Time:\t" +time +
" Topic:\t" + topic +
" Message:\t" + new String(message.getPayload()) +
" QoS:\t" + message.getQos());
} /****************************************************************/
/* End of MqttCallback methods */
/****************************************************************/ static void printHelp() {
System.out.println(
"Syntax:\n\n" +
" Sample [-h] [-a publish|subscribe] [-t <topic>] [-m <message text>]\n" +
" [-s 0|1|2] -b <hostname|IP address>] [-p <brokerport>] [-i <clientID>]\n\n" +
" -h Print this help text and quit\n" +
" -q Quiet mode (default is false)\n" +
" -a Perform the relevant action (default is publish)\n" +
" -t Publish/subscribe to <topic> instead of the default\n" +
" (publish: \"Sample/Java/v3\", subscribe: \"Sample/#\")\n" +
" -m Use <message text> instead of the default\n" +
" (\"Message from MQTTv3 Java client\")\n" +
" -s Use this QoS instead of the default (2)\n" +
" -b Use this name/IP address instead of the default (m2m.eclipse.org)\n" +
" -p Use this port instead of the default (1883)\n\n" +
" -i Use this client ID instead of SampleJavaV3_<action>\n" +
" -c Connect to the server with a clean session (default is false)\n" +
" \n\n Security Options \n" +
" -u Username \n" +
" -z Password \n" +
" \n\n SSL Options \n" +
" -v SSL enabled; true - (default is false) " +
" -k Use this JKS format key store to verify the client\n" +
" -w Passpharse to verify certificates in the keys store\n" +
" -r Use this JKS format keystore to verify the server\n" +
" If javax.net.ssl properties have been set only the -v flag needs to be set\n" +
"Delimit strings containing spaces with \"\"\n\n" +
"Publishers transmit a single message then disconnect from the server.\n" +
"Subscribers remain connected to the server and receive appropriate\n" +
"messages until <enter> is pressed.\n\n"
);
} }
客户端-发布者
只需在configutation里面修改传入的参数即可：
为保证是同一个主题，则需要保证传入-a -t两个参数
-a subscribe -t Sample/Java/v3
最终运行结果：
服务器
订阅者：
发布者
