Added IPAddressLookup (#12097)

core-java-modules/core-java-networking-3/src/main/java/com/baeldung/iplookup/IPAddressLookup.java

@@ -0,0 +1,50 @@
+package com.baeldung.iplookup;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.DatagramSocket;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.net.SocketException;
+import java.net.URL;
+import java.net.UnknownHostException;
+
+public class IPAddressLookup {
+    public static void main(String[] args) {
+        System.out.println("UDP connection IP lookup: " + getLocalIpAddressUdp());
+        System.out.println("Socket connection IP lookup: " + getLocalIpAddressSocket());
+        System.out.println("AWS connection IP lookup: " + getPublicIpAddressAws());
+    }
+
+    public static String getLocalIpAddressUdp() {
+        try (final DatagramSocket datagramSocket = new DatagramSocket()) {
+            datagramSocket.connect(InetAddress.getByName("8.8.8.8"), 12345);
+            return datagramSocket.getLocalAddress().getHostAddress();
+        } catch (SocketException | UnknownHostException exception) {
+            throw new RuntimeException(exception);
+        }
+    }
+
+    public static String getLocalIpAddressSocket() {
+        try (Socket socket = new Socket()) {
+            socket.connect(new InetSocketAddress("google.com", 80));
+            return socket.getLocalAddress().getHostAddress();
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static String getPublicIpAddressAws() {
+        try {
+            String urlString = "http://checkip.amazonaws.com/";
+            URL url = new URL(urlString);
+            try (BufferedReader br = new BufferedReader(new InputStreamReader(url.openStream()))) {
+                return br.readLine();
+            }
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}