Monday, May 30, 2016

Android Datagram/UDP Client example


I posted "Java Datagram/UDP Server and Client, run on raspberry Pi" on my another blogspot. It's the Android version of the client.


MainActivity.java
package com.blogspot.android_er.androidudpclient;

import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    EditText editTextAddress, editTextPort;
    Button buttonConnect;
    TextView textViewState, textViewRx;

    UdpClientHandler udpClientHandler;
    UdpClientThread udpClientThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        editTextAddress = (EditText) findViewById(R.id.address);
        editTextPort = (EditText) findViewById(R.id.port);
        buttonConnect = (Button) findViewById(R.id.connect);
        textViewState = (TextView)findViewById(R.id.state);
        textViewRx = (TextView)findViewById(R.id.received);

        buttonConnect.setOnClickListener(buttonConnectOnClickListener);

        udpClientHandler = new UdpClientHandler(this);
    }

    View.OnClickListener buttonConnectOnClickListener =
            new View.OnClickListener() {

                @Override
                public void onClick(View arg0) {

                    udpClientThread = new UdpClientThread(
                            editTextAddress.getText().toString(),
                            Integer.parseInt(editTextPort.getText().toString()),
                            udpClientHandler);
                    udpClientThread.start();

                    buttonConnect.setEnabled(false);
                }
            };

    private void updateState(String state){
        textViewState.setText(state);
    }

    private void updateRxMsg(String rxmsg){
        textViewRx.append(rxmsg + "\n");
    }

    private void clientEnd(){
        udpClientThread = null;
        textViewState.setText("clientEnd()");
        buttonConnect.setEnabled(true);

    }

    public static class UdpClientHandler extends Handler {
        public static final int UPDATE_STATE = 0;
        public static final int UPDATE_MSG = 1;
        public static final int UPDATE_END = 2;
        private MainActivity parent;

        public UdpClientHandler(MainActivity parent) {
            super();
            this.parent = parent;
        }

        @Override
        public void handleMessage(Message msg) {

            switch (msg.what){
                case UPDATE_STATE:
                    parent.updateState((String)msg.obj);
                    break;
                case UPDATE_MSG:
                    parent.updateRxMsg((String)msg.obj);
                    break;
                case UPDATE_END:
                    parent.clientEnd();
                    break;
                default:
                    super.handleMessage(msg);
            }

        }
    }
}


UdpClientThread.java
package com.blogspot.android_er.androidudpclient;

import android.os.Message;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

public class UdpClientThread extends Thread{

    String dstAddress;
    int dstPort;
    private boolean running;
    MainActivity.UdpClientHandler handler;

    DatagramSocket socket;
    InetAddress address;

    public UdpClientThread(String addr, int port, MainActivity.UdpClientHandler handler) {
        super();
        dstAddress = addr;
        dstPort = port;
        this.handler = handler;
    }

    public void setRunning(boolean running){
        this.running = running;
    }

    private void sendState(String state){
        handler.sendMessage(
                Message.obtain(handler,
                        MainActivity.UdpClientHandler.UPDATE_STATE, state));
    }

    @Override
    public void run() {
        sendState("connecting...");

        running = true;

        try {
            socket = new DatagramSocket();
            address = InetAddress.getByName(dstAddress);

            // send request
            byte[] buf = new byte[256];

            DatagramPacket packet =
                    new DatagramPacket(buf, buf.length, address, dstPort);
            socket.send(packet);

            sendState("connected");

            // get response
            packet = new DatagramPacket(buf, buf.length);


            socket.receive(packet);
            String line = new String(packet.getData(), 0, packet.getLength());

            handler.sendMessage(
                    Message.obtain(handler, MainActivity.UdpClientHandler.UPDATE_MSG, line));

        } catch (SocketException e) {
            e.printStackTrace();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(socket != null){
                socket.close();
                handler.sendEmptyMessage(MainActivity.UdpClientHandler.UPDATE_END);
            }
        }

    }
}


activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    android:orientation="vertical"
    tools:context="com.blogspot.android_er.androidudpclient.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />
    <EditText
        android:id="@+id/address"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="192.168."
        android:hint="dstAddress" />
    <EditText
        android:id="@+id/port"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="4445"
        android:hint="dstPort" />
    <Button
        android:id="@+id/connect"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Connect"/>

    <TextView
        android:id="@+id/state"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="un-initiated"
        android:textSize="20dp"/>

    <TextView
        android:id="@+id/received"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="18dp"/>
</LinearLayout>


uses-permission of "android.permission.INTERNET" is needed in AndroidManifest.xml

download filesDownload the files .

Next:
Android Datagram/UDP Server example

1 comment:

amor enew said...

what do you think about android supporting to raspberry Pi 3