Kommunikation Version 1 UDP Socket

app/build.gradle

         sourceCompatibility JavaVersion.VERSION_1_8
         targetCompatibility JavaVersion.VERSION_1_8
     }
+    buildFeatures {
+        viewBinding true
+    }
 }
 
 dependencies {
     implementation 'androidx.appcompat:appcompat:1.6.1'
     implementation 'com.google.android.material:material:1.8.0'
     implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
+    implementation 'com.google.android.gms:play-services-nearby:18.0.0'
     testImplementation 'junit:junit:4.13.2'
     androidTestImplementation 'androidx.test.ext:junit:1.1.5'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'

app/src/main/AndroidManifest.xml

 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools">
 
+    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.INTERNET" />
+
     <application
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:fullBackupContent="@xml/backup_rules"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
         android:theme="@style/Theme.Ueberwachungssystem"
         tools:targetApi="31">
         <activity
             android:name=".MainActivity"
-            android:exported="true">
+            android:exported="true"
+            android:label="Server">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 

app/src/main/java/com/example/ueberwachungssystem/MainActivity.java

 package com.example.ueberwachungssystem;
-
-import androidx.appcompat.app.AppCompatActivity;
-
+import android.annotation.SuppressLint;
+import android.net.wifi.WifiInfo;
+import android.net.wifi.WifiManager;
 import android.os.Bundle;
+import android.view.View;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.TextView;
+import androidx.appcompat.app.AppCompatActivity;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.PrintWriter;
+import java.net.InetAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 
+@SuppressLint("SetTextI18n")
 public class MainActivity extends AppCompatActivity {
+    TextView tvMessages;
+    TextView tvConnectionInfos;
+
+    WifiCommunication communication;
+    public static String SERVER_IP = "";
+    public static final int SERVER_PORT = 2222;
+    int i=0;
+
+    boolean sending = false;
+
+    String message;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
-        //
+        tvMessages = findViewById(R.id.tvMessages);
+        tvConnectionInfos = findViewById(R.id.tvConnectionInfos);
+        try {
+            SERVER_IP = getLocalIpAddress();
+            tvConnectionInfos.setText("Connection Infos: \n Own IP-Adress: " + SERVER_IP+ " Port: " + SERVER_PORT);
+        } catch (UnknownHostException e) {
+            e.printStackTrace();
+        }
+        Button btnSend = findViewById(R.id.btnSend);
+        btnSend.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                i++;
+                communication.sendTrue("Test" +i);
+            }
+        });
+    }
+    protected void onResume() {
+        super.onResume();
+        communication = new WifiCommunication(MainActivity.this, SERVER_PORT);
+
+    }
+    @Override
+    protected void onPause() {
+        super.onPause();
+        communication.stopCommunication();
+    }
+    private String getLocalIpAddress() throws UnknownHostException {
+        WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE);
+        assert wifiManager != null;
+        WifiInfo wifiInfo = wifiManager.getConnectionInfo();
+        int ipInt = wifiInfo.getIpAddress();
+        return InetAddress.getByAddress(ByteBuffer.allocate(4).order(ByteOrder.LITTLE_ENDIAN).putInt(ipInt).array()).getHostAddress();
     }
-}
+}

app/src/main/java/com/example/ueberwachungssystem/WifiCommunication.java

+package com.example.ueberwachungssystem;
+import android.annotation.SuppressLint;
+
+import java.io.IOException;
+import java.net.DatagramPacket;
+import java.net.DatagramSocket;
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.net.UnknownHostException;
+import java.util.Enumeration;
+
+public class WifiCommunication {
+    private final MainActivity mainActivity;
+    private final InetAddress address;
+    private final int port;
+
+    private String messageToSend;
+    volatile private boolean send;
+    private final DatagramSocket socket;
+    volatile private boolean running;
+    @SuppressLint("SetTextI18n")
+    public WifiCommunication(MainActivity mainActivity, int port) {
+        this.mainActivity = mainActivity;
+        this.port = port;
+        try {
+            socket = new DatagramSocket(this.port);
+            socket.setBroadcast(true);
+            address = InetAddress.getByName("255.255.255.255");
+            running = true;
+            send = false;
+            new ReceiveThread().start();
+            new SendThread().start();
+        } catch (SocketException | UnknownHostException e) {
+            throw new RuntimeException(e);
+        }
+        mainActivity.runOnUiThread(() -> mainActivity.tvMessages.setText("Communication running"));
+    }
+    private class ReceiveThread extends Thread {
+        private StringBuffer rxStringBuffer = new StringBuffer();
+        private String rxString;
+        private String previousRxString = "";
+        @Override
+        public void run() {
+            try {
+                do {
+                    byte[] rxBuffer = new byte[512];
+                    InetAddress fromAdress;
+                    int fromPort;
+                    DatagramPacket rxPacket = new DatagramPacket(rxBuffer, rxBuffer.length);
+                    socket.receive(rxPacket);
+                    fromAdress = rxPacket.getAddress();
+                    fromPort = rxPacket.getPort();
+                    rxString = new String(rxBuffer, 0, rxPacket.getLength());
+                    if(!previousRxString.equals(rxString)) {
+                        mainActivity.runOnUiThread(() -> mainActivity.tvMessages.setText(rxStringBuffer));
+                        rxStringBuffer.append("Adress: " + fromAdress).append(" Port: " + fromPort).append(" Message " +rxString).append("\n");
+                    }
+                    previousRxString = rxString;
+
+                } while (running);
+            }
+            catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+    private class SendThread extends Thread {
+        private int tmpCnt = 0;
+        @Override
+        public void run() {
+            try {
+                do {
+                    if(send)
+                    {
+                        send = false;
+
+                        String txString = getLocalIpAddress() + " sends:" +messageToSend+ " Count: " + tmpCnt++;
+                        byte[] txBuffer = txString.getBytes();
+
+                        DatagramPacket txPacket = new DatagramPacket(txBuffer, txBuffer.length, address, port);
+
+                        for(int i = 0; i < 20; i++) {
+                            socket.send(txPacket);
+                        }
+                    }
+                } while (running);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+    public static String getLocalIpAddress() {
+        try {
+            for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) {
+                NetworkInterface networkInterface = (NetworkInterface) ((Enumeration<?>) en).nextElement();
+                for (Enumeration<InetAddress> addresses = networkInterface.getInetAddresses(); addresses.hasMoreElements();) {
+                    InetAddress inetAddress = addresses.nextElement();
+                    if (!inetAddress.isLoopbackAddress() && inetAddress instanceof Inet4Address) {
+                        return inetAddress.getHostAddress();
+                    }
+                }
+            }
+        } catch (SocketException ex) {
+            ex.printStackTrace();
+        }
+        return null;
+    }
+
+    public void sendTrue(String message){
+        send = true;
+        messageToSend = message;
+    }
+    public void stopCommunication() {
+        running = false;
+        socket.close();
+    }
+}

app/src/main/res/layout/activity_main.xml

-<?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    xmlns:tools="http://schemas.android.com/tools"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    tools:context=".MainActivity">
-
+<?xml version = "1.0" encoding = "utf-8"?>
+<RelativeLayout 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:layout_margin = "16dp"
+    tools:context = ".MainActivity">
+    <TextView
+        android:id = "@+id/tvConnectionInfos"
+        android:layout_width = "match_parent"
+        android:layout_height = "wrap_content"
+        android:inputType = "textMultiLine"
+        android:textAppearance = "@style/Base.TextAppearance.AppCompat.Medium" />
     <TextView
+        android:id = "@+id/tvMessages"
+        android:layout_width = "match_parent"
+        android:layout_height = "wrap_content"
+        android:layout_below="@id/tvConnectionInfos"
+        android:inputType = "textMultiLine"
+        android:textAppearance = "@style/Base.TextAppearance.AppCompat.Medium" />
+
+    <Button
+        android:id="@+id/btnSend"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
-        android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
-
-</androidx.constraintlayout.widget.ConstraintLayout>
+        android:layout_below="@id/tvMessages"
+        android:layout_centerHorizontal="true"
+        android:text="SEND" />
+</RelativeLayout>

settings.gradle

 }
 rootProject.name = "Ueberwachungssystem"
 include ':app'
+include ':app'