Android studio mqtt пример

MQTT Integration in Android Studio

Dec 16, 2017 · 4 min read

Message Queuing Telemetry Transport(MQTT) is a light weight publish subscribe based communication protocol like HyperText Transfer Protocol(HTTP) specially designed for Machine to Machine communication in the field of IoT and IIoT. MQTT uses very small bytes of data to describe the content of the information being transported.

In this demo I will be Paho Android Service which is an interface to the Paho Java MQTT Client library for the Android Platform. Let’s get started.

About the installation

Android uses `Gradle` a s a build system and dependency management, therefor this blog post describes how the Paho Android Service can be added to an application via Gradle. The most convenient way to start a new Android Application is to use Android Studio. To add the Paho Android Service as a dependency to you app add the following parts to your gradle file.

The first part adds the Paho release repository to the gradle config, so that Gradle is able to find the packaged Paho Android Service JAR. The second part adds the Paho Android Service as a dependency to the application. The exclusion of the Android Support library `exclude module: ‘support-v4’` is only necessary if the Android application is using the Android Support Library to backport newer Android features to older Android versions. To have the latest Snapshot release within your application the gradle config below can be used.

Establish the connection

As already mentioned, the Paho Android Service encapsulates the MQTT connection and offers an API for that. To be able to create a binding to the Paho Android Service, the service needs to be declared in the `AndroidManifest.xml`. Add the following within the « tag:

Permissions required in manifest tag

In the first line a helper Function of the Paho MQTT client is used to generate a random user id. The second line creates an instance of an Android MQTT client, that will bind to the Paho Android Service. By calling the `connect` method of the `MqttAndroidClient` the client will asynchronously try to connect to the MQTT broker and return a token. That token can be used to register callbacks, to get notified when either the MQTT-connection gets connected or an error occurs. Running the above example inside an Android `Activity.onCreate` method will print “onSuccess” or “onFailure” to the console.

The `MqttAndroidClient` allows messages to be published via its `publish(topic, MqttMessage)` method. By design the `MqttAndroidClient` dose not queue any messages if the client is not connected and will throw an error when trying to send messages when the client is offline `client.isConnected() == false`. After the first connect, the `IMqttActionListener.onSuccess` method is called when a MQTT connection is established successfully.

Subscriptions can be created via the ` MqttAndroidClient.subscribe` method, which takes the topic and the QOS as parameters and returns a ` IMqttToken`. The token can be used to keep track if the subscription can successfully established or failed. The example below subscribes to the topic “foo/bar” with QOS 1

To disconnect the client call the `disconnect` method of the ` MqttAndroidClient` object. The example below saves the token returned by the `disconnect` method and adds a` IMqttActionListener` to get notified when the client is successfully disconnected.

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Paho Android Service — MQTT Client Library Encyclopedia

Written by Sandro Kock

Published: December 2, 2015

Short info

Pahao Android Service
Language	Java
License	Eclipse Public License v1.0 and Eclipse Distribution License v1.0
Website	eclipse.org/paho/clients/android/
API Style	Asynchronous

Description

The Paho Android Service is an interface to the Paho Java MQTT Client library for the Android Platform. The MQTT connection is encapsulated within an Android-Service that runs in the background of the Android application, keeping it alive when the Android application is switching between different Activities. This layer of abstraction is needed to be able to receive MQTT messages reliably. As the Paho Android Service is based on the Paho Java client library it can be considered stable and used in production. The project is actively maintained by the Eclipse Paho project.

Features

Feature
MQTT 3.1
MQTT 3.1.1
LWT
SSL/TLS
Automatic Reconnect	(On the road map)

Feature
QoS 0
QoS 1
QoS 2
Authentication
Throttling

Usage

Installation

Android uses Gradle as a build system and dependency management, therefor this blog post describes how the Paho Android Service can be added to an application via Gradle. The most convenient way to start a new Android Application is to use Android Studio. To add the Paho Android Service as a dependency to you app add the following parts to your gradle file.

The first part adds the Paho release repository to the gradle config, so that Gradle is able to find the packaged Paho Android Service JAR. The second part adds the Paho Android Service as a dependency to the application. The exclusion of the Android Support library exclude module: ‘support-v4’ is only necessary if the Android application is using the Android Support Library to backport newer Android features to older Android versions. To have the latest Snapshot release within your application the gradle config below can be used.

Connect

As already mentioned, the Paho Android Service encapsulates the MQTT connection and offers an API for that. To be able to create a binding to the Paho Android Service, the service needs to be declared in the AndroidManifest.xml . Add the following within the tag:

The Paho Android Service needs the following permissions to work:

Add those to the tag.

Usually an Android Activity requests or binds to an Android Service to use it, for e.g. the LocationManager to receive updates when the GPS position of the user changes. The Paho Android Service is not meant to bind to directly. Instead the provided MqttAndroidClient client interface binds to the service once created. To create and establish an MQTT-connection use the following code snipped:

In the first line a helper Function of the Paho MQTT client is used to generate a random user id. The second line creates an instance of an Android MQTT client, that will bind to the Paho Android Service. By calling the connect method of the MqttAndroidClient the client will asynchronously try to connect to the MQTT broker and return a token. That token can be used to register callbacks, to get notified when either the MQTT-connection gets connected or an error occurs. Running the above example inside an Android Activity.onCreate method will print “onSuccess” or “onFailure” to the console.

Connect with MQTT 3.1 or MQTT 3.1.1

The MqttAndroidClient will connect with MQTT 3.1.1 by default, with a fallback to 3.1. To intentionally connect with MQTT 3.1 a MqttConnectOptions object can be supplied to the connect method:

Connect with LWT

Like the MQTT version, the Last Will And Testament (LWT) can be added into the MqttConnectOptions object.

Besides the payload of the LWT, everything is straight forward and can be just set. Many MQTT clients assume that the payload is an UTF-8 formatted string and convert the payload automatically. The fact that MQTT is a binary protocol is often hidden with that. By calling String#getBytes the string will be encoded with the systems default charset (UTF-8 on Android).

Connect with Username / Password

Again like the MQTT version and the LWT, the username and password can be supplied within the options object.

Publish

The MqttAndroidClient allows messages to be published via its publish(topic, MqttMessage) method. By design the MqttAndroidClient dose not queue any messages if the client is not connected and will throw an error when trying to send messages when the client is offline client.isConnected() == false . After the first connect, the IMqttActionListener.onSuccess method is called when a MQTT connection is established successfully.

Publish a retained message

To send a retained MQTT message the MqttMessage.retained attribute can be set to true via MqttMessage.setRetained(true) .

Subscribe

Subscriptions can be created via the MqttAndroidClient.subscribe method, which takes the topic and the QOS as parameters and returns a IMqttToken . The token can be used to keep track if the subscription can successfully established or failed. The example below subscribes to the topic “foo/bar” with QOS 1

Unsubscribe

Disconnect

To disconnect the client call the disconnect method of the MqttAndroidClient object. The example below saves the token returned by the disconnect method and adds a IMqttActionListener to get notified when the client is successfully disconnected.

Using SSL / TLS

When connecting with SSL/TLS the MQTT-broker has to use a valid certificate that is trusted via the chain of trust of the Android device or provide a custom Java SocketFactory . Currently I am not aware of any public MQTT broker that can be used to test a SSL/TLS connection without a custom SocketFactory , hopefully this will change in the near feature with Let’s Encrypt in place.

IoT Eclipse provides an MQTT Sandbox running MQTT encrypted on iot.eclipse.org:8883 and supports TLS 1.0, 1.1 and 1.2. Android on the other hand uses a cryptography API library called BouncyCastle. To generate a BouncyCastle keystore (BKS) on a development machine the BounceCastleProvider class is required in the JAVA-Classpath. The JAR containing the class can be downloaded here. To generate the BKS the JDK keytool can be used with the following parameters:

The command assumes that you saved the BouncyCastle JAR and the iot.eclipse.org.crt into the current directory. It will generate a BouncyCastle Keystore names iot.eclipse.org.bks with the password set to eclipse-password .

To actually use the keystore, create a folder named “assets” in the “src/main” directory of you app and copy the iot.eclipse.org.bks file into it. The following example will create a secure MQTT connection to the Eclipse test broker:

The example uses the utility function getSSLSocketFactory of the MqttAndroidClient to create a custom SocketFactory from the BKS keystore input stream.

Full example application

The Eclipse Paho project provides a very detailed example application that demonstrates the capabilities of the Paho Android Service. A packaged application is available at Paho Android Sample. The APK is based on the current development branch in the Eclipse repository. To clone the entire GIT repository use the following command:

The Android sample application source is located in this folder, that can be opened with Android Studio.

About Sandro Kock

Thanks for this guest blog post

Sandro Kock is a mobile developer at SSV Software Systems, responsible for developing mobile solutions, with a focus on IoT/M2M. The maintainer of mqtt-elements, a set of MQTT WebComponents, created with Polymer.

Website В В Contact

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Android MQTT Client

MQTT is a machine-to-machine /Internet of Things connectivity protocol. It’s designed to following use case.

• Lightweight publish-subscribe based messaging protocol for use on top of the TCP/IP protocol.
• Connections to remote locations where a small code is required or the network bandwidth are limited.

MQTT Broker

The publish-subscribe messaging pattern requires a message broker. The broker is responsible for distributing messages to interested clients based on the topic of a message.It also holds the session of all persisted clients including subscriptions and missed messages.

There is a publically accessible sandbox server for the Eclipse IoT projects available at iot.eclipse.org:1883 .

MQTT Client

Eclipse Paho project provides open-source client implementations of MQTT.Paho Android Service is an MQTT client library written in Java for developing applications on Android. The MQTT connection is encapsulated within an Android Service that runs in the background of the Android application, keeping it alive when the Android application is switching between different Activities.The Paho Android Service is an interface to the Paho Java MQTT Client library for the Android Platform.

Installation

Download Paho Android Service and Android MQTT Client library.Go to your libs folder inside app folder and paste all your .jar To add the Paho Android Service as a dependency to you app add the following parts to your gradle file.

Permission

The Paho Android Service needs the following permissions to work.

To be able to create a binding to the Paho Android Service, the service needs to be declared in the AndroidManifest.xml. Add the following within the tag

MQTT Connection Option

MqttAndroidClient will connect with MQTT 3.1.1 by default. To intentionally connect with MQTT 3.1 MqttConnectOptions object can be supplied to the connect method

Clean session

On connection, a client sets the “clean session” flag.If the clean session is set to false, means when the client disconnects, any subscriptions it has will remain and any subsequent QoS 1 or 2 messages will be stored until it connects again in the future. If the clean session is true, then all subscriptions will be removed from the client when it disconnects.

Automatic Reconnect

Sets whether the client will automatically attempt to reconnect to the server if the connection is lost.It will initially wait 1 second before it attempts to reconnect, for every failed to reconnect attempt, the delay will double until it is at 2 minutes at which point the delay will stay at 2 minutes.

Wills

When a client connects to a broker, it may inform the broker that it has a will. This is a message that it wishes the broker to send when the client disconnects unexpectedly. The will message has a topic, QoS and retains status just the same as any other message.

Receive MQTT Message

Disconnect Options

Messages published to the topic if the connection is available, but if it disconnects and connects again offline messages send.Holds the set of options that govern the behavior of Offline (or Disconnected) buffering of messages.

Create MQTT Client

Creates an instance of an Android MQTT client, that will bind to the Paho Android Service. By calling the connect method of the MqttAndroidClient the client will asynchronously try to connect to the MQTT broker and return a token. That token can be used to register callbacks, to get notified when either the MQTT-connection gets connected or an error occurs

Publish Message

The MqttAndroidClient allows messages to be published via its publish method.

Subscribe

Subscriptions can be created via the MqttAndroidClient.subscribe method, which takes the topic and the QOS as parameters and returns a IMqttToken .

Unsubscribe

Disconnect MQTT Client

Download this project from GitHub.

MQTTBox

MQTTBox enables you to create MQTT clients to publish or subscript topics, create MQTT virtual device networks, load test MQTT devices or brokers.

1.Create MQTT client

2.Config MQTT client
Host : iot.eclipse.org:1883 Protocol : mqtt/tcp 3.Publish/Subscribe

13 Comments

Really helpful tutorial. Can i use this project with other broker like HiveMq and thingspeak ??

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