Java Language Create file fports with the first line as a hostname that needs to

Question

Java Language

Create file fports with the first line as a hostname that needs to be scanned for certain ports to be opened on it (the values shown are examples... you need to select your own values): host name 80 22 443 445 Write a java program to accomplish the following: Open file fports Read the hostname to be scanned and store it in variable hostname Read the ports into array of integers ports Create array status (of boolean type) Write a for loop to scan one port at a time and make note of its status (true if the port is open... false if the port is closed) Write a for loop to store the result of the scan in file fports _result as follows (the values shown are examples): host name 80 Open 22 Close 443 Open 445 Close Write a for loop to print the result of the scan as well

Explanation / Answer

I tried my best and commented the code for you. In case of difficulties, ping me...

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

/**
*
* @author Sam
*/
public class PortChecker {

    public static void main(final String... args) throws InterruptedException, ExecutionException, FileNotFoundException, IOException {
        final ExecutorService es = Executors.newFixedThreadPool(20);
        BufferedReader br = new BufferedReader(new FileReader("fports"));
        final String ip = br.readLine(); //read ip or hostnaem
        final int timeout = 200;
        System.out.println(ip);
        String port;
        final List<Integer> ports = new ArrayList<>();
        while ((port = br.readLine()) != null) {
            ports.add(Integer.parseInt(port)); //read and addd ports
            System.out.println(port); //print port
        }
        final List<Future<Boolean>> futures = new ArrayList<>();
        ports.stream().forEach((p) -> {
            futures.add(portIsOpen(es, ip, p, timeout)); //try for each saved ports
        });
        es.shutdown();
        System.out.println(" ");
        System.out.println(ip);
        PrintWriter pw = new PrintWriter("fports_results");
        for (int i = 0; i < ports.size(); i++) {
            pw.println(ports.get(i) + " " + (futures.get(i).get() ? "open" : "close")); //print port and status as open/clsoe
        }
        pw.flush();
        pw.close();
    }

    public static Future<Boolean> portIsOpen(final ExecutorService executorService, final String ip, final int port, final int timeout) { //to parallelizeand reduce time
        return executorService.submit(() -> {
            try (Socket socket = new Socket()) {
                socket.connect(new InetSocketAddress(ip, port), timeout);
                return true; //if port open,return true
            } catch (Exception ex) {
                return false; //if closed
            }
        });
    }
}

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