In Java how to check if Socket is Alive, Connection is Active on specific Port? isSocketAlive() Utility

This is a very simple free Java Utility which tells you if you could establish a socket connection to different hosts on specific ports. Feel free to use it in production environment.

In Java InetSocketAddress creates a socket address from a hostname and a port number. We call it as server socket in Java. Socket library with Non blocking IO and Simple IO is a very big topic.

In this tutorial we will go over simple utility which we are calling isSocketAlive(String hostname, int port) which returns boolean result – true/false.

Let’s get started:

Step-1

Create class CrunchifyIsSocketAliveUtility.java

Step-2

Create utility isSocketAliveUitlitybyCrunchify(hostname, port) which returns true/false

Step-3

In main method, we will do 5 tests

1. Start Apache Tomcat Server in Eclipse IDE and try to connect to localhost on port 8080
   • Install Apache Tomcat in Eclipse Tutorial link
2. Now connect to port 8081 which will be a failure scenario
3. We will also connect to site crunchify.com on port 80. As Crunchify.com runs on Apache Server by default port is 80.
4. We will connect to site pro.crunchify.com on port 80 –> Success
5. Connect to site pro.crunchify.com and 81 –> It will be failure

Provide default timeout to 2 seconds.

socket.connect(socketAddress, timeout) connects socket to the server with a specified timeout value.

A timeout of zero is interpreted as an infinite timeout. The connection will then block until established or an error occurs.

We are catching SocketTimeException and IOException in case of error.

This Java Program will help you in case you have below questions:

• Java socket programming tutorial
• Writing the Server Side of a Socket
• Sockets programming in Java
• java socket connection example
• Java client/server application with sockets
• java serversocket example
• java.net.socket example
• listen socket connection java example

Complete Java Program:

package crunchify.com.tutorials;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketTimeoutException;

/**
 * @author Crunchify.com
 * 
 */

public class CrunchifyIsSocketAliveUtility {

        public static void main(String[] args) {

                // Run Apache Tomcat server on Port 8080 in Eclipse to see success
                // result
                log(isSocketAliveUitlitybyCrunchify("localhost", 8080));

                // Now change port to 8081 and you should see failure
                log(isSocketAliveUitlitybyCrunchify("localhost", 8081));

                // Connect to Crunchify.com on port 80
                log(isSocketAliveUitlitybyCrunchify("crunchify.com", 80));

                // Connection to pro.crunchify.com on port 81
                log(isSocketAliveUitlitybyCrunchify("pro.crunchify.com", 81));

                // Connection to pro.crunchify.com on port 80
                log(isSocketAliveUitlitybyCrunchify("pro.crunchify.com", 80));
        }

        /**
         * Crunchify's isAlive Utility
         * 
         * @param hostName
         * @param port
         * @return boolean - true/false
         */
        public static boolean isSocketAliveUitlitybyCrunchify(String hostName, int port) {
                boolean isAlive = false;

                // Creates a socket address from a hostname and a port number
                SocketAddress socketAddress = new InetSocketAddress(hostName, port);
                Socket socket = new Socket();

                // Timeout required - it's in milliseconds
                int timeout = 2000;

                log("hostName: " + hostName + ", port: " + port);
                try {
                        socket.connect(socketAddress, timeout);
                        socket.close();
                        isAlive = true;

                } catch (SocketTimeoutException exception) {
                        System.out.println("SocketTimeoutException " + hostName + ":" + port + ". " + exception.getMessage());
                } catch (IOException exception) {
                        System.out.println(
                                        "IOException - Unable to connect to " + hostName + ":" + port + ". " + exception.getMessage());
                }
                return isAlive;
        }

        // Simple log utility
        private static void log(String string) {
                System.out.println(string);
        }

        // Simple log utility returns boolean result
        private static void log(boolean isAlive) {
                System.out.println("isAlive result: " + isAlive + "\n");
        }

}

Output:

hostName: localhost, port: 8080
isAlive result: true

hostName: localhost, port: 8081
IOException - Unable to connect to localhost:8081. Connection refused
isAlive result: false

hostName: crunchify.com, port: 80
isAlive result: true

hostName: pro.crunchify.com, port: 81
SocketTimeoutException pro.crunchify.com:81. connect timed out
isAlive result: false

hostName: pro.crunchify.com, port: 80
isAlive result: true

The post In Java how to check if Socket is Alive, Connection is Active on specific Port? isSocketAlive() Utility appeared first on Crunchify.