Java Networking Examples : How To Get HTTP Header Information of URL

Intro

This examples will demonstrates how to get header information of URL such as status code, response code, content type, and etc.

To get a header information of URL, you can use HttpURLConnection.getHeaderFields() method.

Examples

package com.freesamplecode.java.networking;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class GetHeaderInformationURLDemo {
 public static void main(String[] args){
  
  try {
   //create URL object
   URL url = new URL("http://free-samplecode.blogspot.com/p/java.html");
   
   //open URL connection
   HttpURLConnection httpUrlConnection =  (HttpURLConnection) url.openConnection();
   
   //get all URL header informations
   Map headerField = httpUrlConnection.getHeaderFields();
   
   Set set = headerField.entrySet();
   
   Iterator it = set.iterator();
   
   while(it.hasNext()){
    System.out.println(it.next());
   }
   

  } catch (MalformedURLException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
 }
}

Output

null=[HTTP/1.1 200 OK]
Expires=[Sun, 27 Mar 2016 13:31:17 GMT]
X-XSS-Protection=[1; mode=block]
Last-Modified=[Sun, 27 Mar 2016 13:15:17 GMT]
Connection=[Keep-Alive]
Server=[GSE]
X-Content-Type-Options=[nosniff]
Cache-Control=[private, max-age=0]
Date=[Sun, 27 Mar 2016 13:31:17 GMT]
Vary=[Accept-Encoding]
Transfer-Encoding=[chunked]
Content-Type=[text/html; charset=UTF-8]
Accept-Ranges=[none]

Screenshot

Java Networking Examples : How To Display Source Code Of A Web Page Using URLConnection

Intro

This examples will demonstrates how to display source code of a web page using URLConnection class.

Examples

package com.freesamplecode.java.networking;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class GetSourceCodeWebDemo {
 public static void main(String[] args){
  try {
   
   //create URL object
   URL url = new URL("http://free-samplecode.blogspot.com/p/java.html");
   
   //open URL connection
   URLConnection urlConnection = url.openConnection();
   
   //get stream of URL 
   InputStream is = urlConnection.getInputStream();
   int i = 0;
   while((i = is.read()) != -1){
    System.out.print((char)i);
   }
  } catch (MalformedURLException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
  
 }
}

Output

Java Network Example : How To Get URL Properties

Intro

This example, will demonstrates how to get URL properties such as URL port, URL host, URL path, and etc using Java Network programming.

Example

package com.freesamplecode.java.networking;

import java.net.MalformedURLException;
import java.net.URL;

public class GetURLPropertiesDemo {
 public static void main(String[] args){
  URL url = null;
  
  try {
   url = new URL("http://free-samplecode.blogspot.com/p/java.html");
   System.out.println("Protocol : "+url.getProtocol());
   System.out.println("Host : "+url.getHost());
   System.out.println("Port : "+url.getPort());
   System.out.println("Query : "+url.getQuery());
   System.out.println("Path : "+url.getPath());
   System.out.println("User Info : "+url.getUserInfo());
  } catch (MalformedURLException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
 }
}

Output

Protocol : http
Host : free-samplecode.blogspot.com
Port : -1
Query : null
Path : /p/java.html
User Info : null

Screenshot

Java Network Example : How To Get Contents Of The URL

Intro

This examples, will demonstrates how to get content of the URL using Java program. The contents are in the HTML format.

Example

package com.freesamplecode.java.networking;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

public class GetContentURLDemo {
 public static void main(String[] args){
  URL url = null;
  InputStream is = null;
  
  try {
   
   // URL site
   url = new URL("http://free-samplecode.blogspot.com/p/java.html");
   
   //open stream
   is = url.openStream();
   
   byte[] b = new byte[1024];
   while(is.read(b) != -1){
    System.out.println(new String(b));
   }
   
  } catch (MalformedURLException e) {
   e.printStackTrace();
  } catch (IOException e){
   e.printStackTrace();
  }
  
 }
}

Output

Java Networking Example : How To Get Localhost Address And Localhost Name

Intro

To get localhost address and localhost name, you can use getLocalHost() method of InetAddress class.

Example

package com.freesamplecode.java.networking;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class GetLocalhostDemo {
 public static void main(String[] args){
  InetAddress address;
  try {
   address = InetAddress.getLocalHost();
   System.out.println("Localhost Address :" +address.getHostAddress());
   System.out.println("Localhost Name :" +address.getHostName());
  } catch (UnknownHostException e) {
   e.printStackTrace();
  }
  
 }
}

Output

Localhost Address :192.168.1.101
Localhost Name :mobile214

Screenshot

Java Networking Example : How To Get IP Address Of A Host

Intro

To get IP address of a host, you can use the InetAddress class. By calling getHostAddress() method, you can get an IP address of the host.

Example

package com.freesamplecode.java.networking;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class GetIPAddressByHost {
 public static void main(String[] args){
  try {
   InetAddress host = InetAddress.getByName("free-samplecode.blogspot.com");
   System.out.println("IP Address : "+host.getHostAddress());
  } catch (UnknownHostException e) {
   e.printStackTrace();
  }
 }
}

Ouput

IP Address : 74.125.200.132

Screenshot