Java

Java is a general-purpose computer programming language that is concurrent, class-based, object-oriented, and specifically designed to have as few implementation dependencies as possible. It is intended to let application developers “write once, run anywhere” (WORA), meaning that compiled Java code can run on all platforms that support Java without the need for recompilation. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of computer architecture

Realizar petición HTTP mediante el método POST utilizando librerías de Apache

/*Importar librerías:
commons-codec
commons-httpclient
commons-logging
*/

import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.PostMethod;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class MetodoPOST {
	public static void main(String args[]) {
		HttpClient client = new HttpClient();
		client.getParams().setParameter("http.useragent", "");
		
		BufferedReader br = null;

		PostMethod method = new PostMethod("http://www.jesusninoc.com/getypost/examplepost.php");
		method.addParameter("nombre", "Juan");
		method.addParameter("edad", "34");
		
		try{
			int returnCode = client.executeMethod(method);
			if(returnCode == HttpStatus.SC_NOT_IMPLEMENTED) {
				System.err.println("Método POST no implementado");
				// still consume the response body
				method.getResponseBodyAsString();
				} else {
					br = new BufferedReader(new InputStreamReader(method.getResponseBodyAsStream()));
					String readLine;
					while(((readLine = br.readLine()) != null)) {
						System.err.println(readLine);
						}
					}
			} catch (Exception e) {
				System.err.println(e);
				} finally {
					method.releaseConnection();
					if(br != null) try { br.close(); } catch (Exception fe) {}
					}
		}
	}

/*Importar librerías:

commons-codec

commons-httpclient

commons-logging

import org.apache.commons.httpclient.HttpClient;

import org.apache.commons.httpclient.HttpStatus;

import org.apache.commons.httpclient.methods.PostMethod;

import java.io.BufferedReader;

import java.io.InputStreamReader;

public class MetodoPOST {

public static void main(String args[]) {

HttpClient client = new HttpClient();

client.getParams().setParameter("http.useragent", "");

BufferedReader br = null;

PostMethod method = new PostMethod("http://www.jesusninoc.com/getypost/examplepost.php");

method.addParameter("nombre", "Juan");

method.addParameter("edad", "34");

try{

int returnCode = client.executeMethod(method);

if(returnCode == HttpStatus.SC_NOT_IMPLEMENTED) {

System.err.println("Método POST no implementado");

// still consume the response body

method.getResponseBodyAsString();

} else {

br = new BufferedReader(new InputStreamReader(method.getResponseBodyAsStream()));

String readLine;

while(((readLine = br.readLine()) != null)) {

System.err.println(readLine);

}

} catch (Exception e) {

System.err.println(e);

} finally {

method.releaseConnection();

if(br != null) try { br.close(); } catch (Exception fe) {}

}

Ejecutar y guardar el comando ‘arp’ utilizando ProcessBuilder

import java.io.IOException;

public class ProcesoArp{
	public static void main(String[] args)
	{
		ProcessBuilder pb = new ProcessBuilder("cmd", "/C", "arp -a > F:\\java\\arp.txt");
		try
		{
			pb.start();
			}
		catch (IOException e)
		{
			System.out.println(e.getMessage());
			}
		}
	}

import java.io.IOException;

public class ProcesoArp{

public static void main(String[] args)

{

ProcessBuilder pb = new ProcessBuilder("cmd", "/C", "arp -a > F:\\java\\arp.txt");

try

{

pb.start();

}

catch (IOException e)

{

System.out.println(e.getMessage());

}

Analizar direcciones IP para detectar puertos abiertos (versión 2)

import java.net.*;
import java.io.*;

public class ScannerIP {
	public static void main(String[] args) {
	//Introducir como argumento de entrada las direcciones IP
		for (int i = 0; i < args.length; i++) {
			//Comprobar puertos del 80 al 90
			for (int port = 80; port < 90; port++) {
				try {
					Socket SocketIP = new Socket(args[i], port);
					System.out.println("Conectar a " + SocketIP.getInetAddress() + " en el puerto " + SocketIP.getPort() + " desde el puerto " + SocketIP.getLocalPort() + " en " + SocketIP.getLocalAddress());
					SocketIP.close();
					} // end try
				catch (UnknownHostException ex) {
					System.err.println(ex);
					}
				catch (SocketException ex) {
					System.err.println(ex);
					}
				catch (IOException ex) {
					System.err.println(ex);
					}
				} // fin for IP
			} // fin for port
		} // fin main
	} // fin ScannerIP

import java.net.*;

import java.io.*;

public class ScannerIP {

public static void main(String[] args) {

//Introducir como argumento de entrada las direcciones IP

for (int i = 0; i < args.length; i++) {

//Comprobar puertos del 80 al 90

for (int port = 80; port < 90; port++) {

try {

Socket SocketIP = new Socket(args[i], port);

System.out.println("Conectar a " + SocketIP.getInetAddress() + " en el puerto " + SocketIP.getPort() + " desde el puerto " + SocketIP.getLocalPort() + " en " + SocketIP.getLocalAddress());

SocketIP.close();

} // end try

catch (UnknownHostException ex) {

System.err.println(ex);

}

catch (SocketException ex) {

System.err.println(ex);

}

catch (IOException ex) {

System.err.println(ex);

}

} // fin for IP

} // fin for port

} // fin main

} // fin ScannerIP

Analizar direcciones IP para detectar puertos abiertos (versión 1)

import java.net.*;
import java.io.*;

public class ScannerIP {
	public static void main(String[] args) {
		//Introducir como argumento de entrada las direcciones IP
		for (int i = 0; i < args.length; i++) {
			try {
				Socket SocketIP = new Socket(args[i], 80);
				System.out.println("Conectar a " + SocketIP.getInetAddress() + " en el puerto " + SocketIP.getPort() + " desde el puerto " + SocketIP.getLocalPort() + " en " + SocketIP.getLocalAddress());
				SocketIP.close();
				} // end try
			catch (UnknownHostException ex) {
				System.err.println(ex);
				}
			catch (SocketException ex) {
				System.err.println(ex);
				}
			catch (IOException ex) {
				System.err.println(ex);
				}
			} // fin for
		} // fin main
	} // fin ScannerIP

import java.net.*;

import java.io.*;

public class ScannerIP {

public static void main(String[] args) {

//Introducir como argumento de entrada las direcciones IP

for (int i = 0; i < args.length; i++) {

try {

Socket SocketIP = new Socket(args[i], 80);

System.out.println("Conectar a " + SocketIP.getInetAddress() + " en el puerto " + SocketIP.getPort() + " desde el puerto " + SocketIP.getLocalPort() + " en " + SocketIP.getLocalAddress());

SocketIP.close();

} // end try

catch (UnknownHostException ex) {

System.err.println(ex);

}

catch (SocketException ex) {

System.err.println(ex);

}

catch (IOException ex) {

System.err.println(ex);

}

} // fin for

} // fin main

} // fin ScannerIP

Monitorización de aplicaciones Java con VisualVM

El proceso HolaMundo con el siguiente código

import java.util.concurrent.TimeUnit;

public class HolaMundo
{
	public static void main(String[] args) throws InterruptedException
	{
		System.out.print ("Hola mundos");
		TimeUnit.SECONDS.sleep(100);
	}
}

import java.util.concurrent.TimeUnit;

public class HolaMundo

{

public static void main(String[] args) throws InterruptedException

{

System.out.print ("Hola mundos");

TimeUnit.SECONDS.sleep(100);

}

Se monitoriza desde VisualVM mostrando los string que se utilizan en el proceso HolaMundo

VisualVM

VisualVM is a visual tool integrating several commandline JDK tools and lightweight profiling capabilities. Designed for both production and development time use, it further enhances the capability of monitoring and performance analysis for the Java SE platform. Download https://visualvm.java.net/

Curso de Java con ejemplos

Procesos Create operating system processes Create and destroy operating system processes Crear un proceso utilizando Runtime Crear un proceso utilizando ProcessBuilder Lanzar un programa del sistema operativo como argumento desde la línea de comandos Ejecutar y guardar el comando ‘arp’ utilizando ProcessBuilder Hilos Crear un hilo implementando el interfaz Runnable Crear un hilo heredando de…
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MulticastSocket (Datagram Socket UDP)

import java.net.*;
import java.io.*;

public class MulticastS{
	public static void main(String args[])
	{
		try
		{
			int port = 2020;
			//224.0.0.1 ... 224.0.0.255
			InetAddress multicastGroupIP = InetAddress.getByName("224.0.0.5");
			System.out.println(multicastGroupIP);
			MulticastSocket socket = new MulticastSocket(port);

			socket.joinGroup(multicastGroupIP);
			
			byte[] m = "Hi".getBytes();
			DatagramPacket send = new DatagramPacket(m, m.length, multicastGroupIP, port);
			socket.send(send);
			
			byte[] bufer = new byte[1000];
			String linea;
			
			while (true)
			{
				DatagramPacket receive = new DatagramPacket(bufer, bufer.length);
				socket.receive(receive);
				linea = new String(receive.getData(), 0, receive.getLength());
				System.out.println("Receive: " + linea);
				
				//Break if "Bye"
				if (linea.equals("Bye")) 
					{
					socket.close();
					break;
					}
				}
			socket.leaveGroup(multicastGroupIP);
			}
		catch (SocketException e) {}
		catch (IOException e) {}
		}
	}

import java.net.*;

import java.io.*;

public class MulticastS{

public static void main(String args[])

{

try

{

int port = 2020;

//224.0.0.1 ... 224.0.0.255

InetAddress multicastGroupIP = InetAddress.getByName("224.0.0.5");

System.out.println(multicastGroupIP);

MulticastSocket socket = new MulticastSocket(port);

socket.joinGroup(multicastGroupIP);

byte[] m = "Hi".getBytes();

DatagramPacket send = new DatagramPacket(m, m.length, multicastGroupIP, port);

socket.send(send);

byte[] bufer = new byte[1000];

String linea;

while (true)

{

DatagramPacket receive = new DatagramPacket(bufer, bufer.length);

socket.receive(receive);

linea = new String(receive.getData(), 0, receive.getLength());

System.out.println("Receive: " + linea);

//Break if "Bye"

if (linea.equals("Bye"))

{

socket.close();

break;

}

socket.leaveGroup(multicastGroupIP);

}

catch (SocketException e) {}

catch (IOException e) {}

}

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