lbt4j - Linux Bluetooth Library for Java

About

lbt4j is a Java API that offers (over a JNI-library) access to BlueZ over it's DBus Interface Model targeted for Raspberry PI.

It is generated by using CodegenJ, which depends on Gnomes's D-Bus library, documentation and code generator gdbus-codegen.

CodegenJ reads [D-Bus Introspection XML] (https://dbus.freedesktop.org/doc/dbus-specification.html#introspection-format) files and generates the API, javadoc and a stuff to build the native library (bundled in native-jar).

The xml file is present under src/main/resources. The introspection format is extended by API documenation taken from BlueZ and CodegenJ-specific annotations.

Alternatives

• DBus-Java - generic D-Bus API
• TinyB - Great guide and examples, C++ and Java supported.
• BlueCove - a J2SE implementation (J2ME)

Links:

• JABWT1 - J2ME article
• JABWT2 - J2ME article

Build

Tested with BlueZ 5.40 and 5.41 patched by https://gist.github.com/pelwell/c8230c48ea24698527cd/archive/3b07a1eb296862da889609a84f8e10b299b7442d.zip

Maven

You can build the jar file and documentation with maven:

mvn clean package site site:run

Open the project documentation in your web browser on http://localhost:9000 or open it without site:run under

target/site/index.html

You can compile the jni library from the target (jni/ and classes/):

cd target/jni

make clean all

Download

Get the API jar and javadoc here: MavenCentral
Download the native library bin (zip or tar) at MavenCentral

HOWTO

This projects builds an Javi API jar to access the D-Bus interfaces of BlueZ.
It is to be used with the The native library build in [lbt4j-lib] (https://github.com/olir/lbt4j-lib).

If you need to setup an Raspberry PI read RaspberryPI3_Installation_Walkthrough.md.

Usage: Invoke your client implementation like this:

java -cp testclasses:lbt4j-0.3.1.jar -Djava.library.path=jni TestClient

where jni is the folder the native library libbluezdbus.so should be placed.

Example

import java.io.IOException;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.bluez.Adapter1;
import org.bluez.Device1;
import org.bluez.GattCharacteristic1;
import org.bluez.GattService1;

import de.serviceflow.codegenj.ObjectManager;

...

public static void main(String[] args) throws InterruptedException {

    ObjectManager m = ObjectManager.getInstance();
    ObjectManager.getLogger().setLevel(Level.FINE);         

    // Show what's on the bus:
    m.dump();

    List<Adapter1> adapters = m.getAdapters();
    System.out.println(" ==> # = " + adapters.size());

    // Find our bloetooth adapter, and start Discovery ...
    Adapter1 defaultAdapter = null;
    for (Adapter1 a : adapters) {
        System.out.println(" ==> Adapter: " + a.getName());
        try {
            a.startDiscovery();
        } catch (IOException e) {
            System.out.println(" ... ignored.");
            continue;
        }
        defaultAdapter = a;
    }
    if (defaultAdapter==null) {
        System.out.println("no useable adapter found. Exit.");
        System.exit(1);
    }

    // Wait for devices to be discovered
    Thread.sleep(5000);

    Adapter1 a = defaultAdapter;
        for (Device1 d : a.getDevices()) {
            if ("CC2650 SensorTag".equals(d.getName())) {
                System.out.println(" ==> Device: " + d.getName());
                try {
                    if (!d.getConnected()) {
                        d.connect();
                        System.out.println(" ... connected.");
                    }
                    else {
                        System.out.println(" ... already connected.");
                    }
                } catch (IOException e) {
                    System.out.println(" ... ignored: "+e.getMessage());
                }
            }
            else {
                System.out.println(" --> Device " + d.getName()+" skipped.");
            }
        }

    // Use the API to traverse through the tree.
    System.out.println("*** Object Tree:");
    for (Adapter1 a : adapters) {
        System.out.println(" ... adapter "+a.getObjectPath()+"  "+a.getName());
        for (Device1 d : a.getDevices()) {
            System.out.println("  .. device "+d.getObjectPath()+"  "+d.getName());
            for (GattService1 s :  d.getServices()) {
                System.out.println("   . service "+s.getObjectPath()+"  "+s.getUUID());
                for (GattCharacteristic1 c :  s.getCharacteristics()) {
                    System.out.println("    . char "+c.getObjectPath()+"  "+c.getUUID());
                }
            }
        }
    }

    try {
        defaultAdapter.stopDiscovery();
        System.out.println(" ... stopped.");
    } catch (IOException e) {
        System.out.println(" ... ignored.");
    }

}