RosJava在Android和Java程序中的使用

由于网上大多贴出的都是核心代码，一些细节配置我是在github和ros wiki上找到的，下面给大家总结出来，可以直接配置运行了

Android篇：

1.在Android studio的build.gradle(Project:xx)中替换和添加下面代码

buildscript {
    apply from: "https://github.com/rosjava/android_core/raw/kinetic/buildscript.gradle"
}
subprojects {
    apply plugin: 'ros-android'

    afterEvaluate { project ->
        android {
            // Exclude a few files that are duplicated across our dependencies and
            // prevent packaging Android applications.
            packagingOptions {
                exclude "META-INF/LICENSE.txt"
                exclude "META-INF/NOTICE.txt"
            }
        }
    }
}

2.在build.grade(Module:app)中的dependencies中添加

implementation 'org.ros.android_core:android_core_components:0.4.0'

3.在AndroidManifest.xml中添加

权限

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

<application>中添加

<activity android:name="org.ros.android.MasterChooser" />

<service android:name="org.ros.android.NodeMainExecutorService" >
    <intent-filter>
        <action android:name="org.ros.android.NodeMainExecutorService" />
    </intent-filter>
</service>

application的属性中添加

xmlns:tools="http://schemas.android.com/tools"
tools:replace="android:icon"

4.代码部分

public class Listener extends AbstractNodeMain {

    @Override
    public GraphName getDefaultNodeName() {
        return GraphName.of("rosjava_pubsub/listener");
    }

    @Override
    public void onStart(ConnectedNode connectedNode) {
        final Log log=connectedNode.getLog();
        Subscriber<std_msgs.String> subscriber=connectedNode.newSubscriber("chatter", String._TYPE);
        subscriber.addMessageListener(new MessageListener<std_msgs.String>() {
            @Override
            public void onNewMessage(std_msgs.String message) {
                log.info("I heard: \"" + message.getData() + "\"");
            }
        });
    }
}

public class Talker extends AbstractNodeMain {

    @Override
    public GraphName getDefaultNodeName() {
        return GraphName.of("rosjava_pubsub/talker");
    }

    @Override
    public void onStart(ConnectedNode connectedNode) {
        final Publisher<std_msgs.String> publisher=connectedNode.newPublisher("chatter", String._TYPE);
        connectedNode.executeCancellableLoop(new CancellableLoop() {
            private int sequenceNumber;

            @Override
            protected void setup() {
                sequenceNumber=0;
            }

            @Override
            protected void loop() throws InterruptedException {
                std_msgs.String str=publisher.newMessage();
                str.setData("Android Hello world! "+sequenceNumber);
                publisher.publish(str);
                sequenceNumber++;
                Thread.sleep(1000);
            }
        });
    }

}

public class RosTestActivity extends RosActivity {
    private RosTextView<std_msgs.String> rosTextView;

    public RosTestActivity() {
        super("Robot","Robot");
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ros_test);
        rosTextView=findViewById(R.id.textRos);
        rosTextView.setTopicName("chatter");
        rosTextView.setMessageType(String._TYPE);
        rosTextView.setMessageToStringCallable(new MessageCallable<java.lang.String, String>() {
            @Override
            public java.lang.String call(std_msgs.String message) {
                return message.getData();
            }
        });
    }

    @Override
    protected void init(NodeMainExecutor nodeMainExecutor) {
        NodeConfiguration configuration=NodeConfiguration.newPublic(getRosHostname());
        Log.d("",InetAddressFactory.newNonLoopback().getHostAddress());
        configuration.setMasterUri(getMasterUri());
        Listener listener=new Listener();
        Talker talker=new Talker();
        nodeMainExecutor.execute(listener,configuration);
        nodeMainExecutor.execute(talker,configuration);
        nodeMainExecutor.execute(rosTextView,configuration);

    }

    @SuppressLint("StaticFieldLeak")
    @Override
    public void startMasterChooser() {
        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getBaseContext());
        java.lang.String masterURI = prefs.getString("masterURI", "http://192.168.1.111:11311");

        Intent data = new Intent();
        data.putExtra("ROS_MASTER_URI", masterURI);
        onActivityResult(0, RESULT_OK, data);

    }
}

总结：startMasterChooser()这个函数被我重写了，如果不重写大家可以试一下，会默认跳转到MasterChooser这个Activity里，这里在app UI会显示一个连接网络的界面，但是我们大多时候是不想用它提供的界面的，所以重写这个函数就很有必要了。

Java篇

直接上代码了（这里的Listener和Talker和Android的一样，就不重复贴出来了）

public class Test {
    private static Talker talker;
    private static Linstener linstener;
    public static NodeMainExecutor mNodeMainExecutorService;
    public static void main(String[] args) {
        init();
    }

    private static void init() {
        mNodeMainExecutorService=DefaultNodeMainExecutor.newDefault();
        startTask();
    }
    
    private static String getDefaultHostAddress() {
        return InetAddressFactory.newNonLoopback().getHostAddress();
    }
    
    private static void startTask() {

        NodeConfiguration nodeConfiguration = NodeConfiguration.newPublic(getDefaultHostAddress());
        linstener = new Linstener();
        talker = new Talker();
        mNodeMainExecutorService.execute(linstener, nodeConfiguration);
        mNodeMainExecutorService.execute(talker, nodeConfiguration);
    }

}

总结：这是最简化的代码，启程序的时候要先启动roscore（我是用命令行启的），如果想在代码中启动roscore需要使用RosCore

private  RosCore rosCore;

rosCore = RosCore.newPublic("192.168.1.111", 11311);

rosCore.start();
rosCore.awaitStart();

希望能帮助到大家！