Example CODE to show information on URLs

From:

"Andrew Thompson" <andrewthommo@gmail.com>

Newsgroups:

comp.lang.java.help

Date:

5 Dec 2006 18:34:22 -0800

Message-ID:

<1165372462.288448.125310@80g2000cwy.googlegroups.com>

<sscce>
import java.awt.Dimension;

import javax.swing.JOptionPane;
import javax.swing.JEditorPane;
import javax.swing.JScrollPane;

import java.net.URL;
import java.net.URLConnection;

import java.util.Date;
import java.util.Iterator;

/** Accepts an URL and dumps information relevant to it.
Does not attempt to display the actual content.

Note the response codes carefully.
E.G. If an URL's has a response code of '403 Forbidden',
this means the URL is not allowed, either for general
browsing, or more specifically, to connections that
identify themselves as 'bot'.

For more information on response codes, see
http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html

@version 1.0 2006/12/06 */
public class ShowHeaders {

  public static void main(String[] args) {
    String address = null;
    if (args.length==0) {
      address = JOptionPane.showInputDialog(
        null,
        "Show information for which URL?");
    } else {
      address = args[0];
    }
    JEditorPane jep = new JEditorPane();
    try {
      URL url = new URL(address);
      URLConnection urlc = url.openConnection();
      urlc.setRequestProperty("user-agent", "bot");

      StringBuffer sb = new StringBuffer();

      // show the URL/address
      sb.append( "URL: \t" + url );

      /** Show the reported content-type.
      Some common content types..
      HTML - text/html
      JNLP - application/x-java-jnlp-file
      ZIP - application/zip */
      sb.append( "\n\ncontent-type: \t" +
        urlc.getContentType() );

      // display dates..
      sb.append( "\n\nDate: \t" +
        new Date(urlc.getDate()) );
      sb.append( "\nExpires: \t" +
        new Date(urlc.getExpiration()) );

      // display user interaction params.
      sb.append( "\n\nAllow User Interaction: \t" +
        urlc.getAllowUserInteraction() );
      sb.append( "\nDefault Allow Interaction: \t" +
        urlc.getDefaultAllowUserInteraction() );

      /** add the encoding and length
      (often not available) */
      sb.append( "\n\nEncoding: \t" +
        urlc.getContentEncoding() );
      sb.append( "\nLength: \t" +
        urlc.getContentLength() );

      // dump the header fields
      sb.append( "\n\nHeader Fields:" );

      Iterator it = urlc.getHeaderFields().
        values().iterator();
      while ( it.hasNext() ) {
        sb.append("\n" + it.next());
      }

      jep.setText( sb.toString() );

    } catch(Exception e) {
      // tell the user what went wrong
      jep.setText( "URL: \t'" + address + "'\n\n" +
        e.toString() );
    }
    JScrollPane jsp = new JScrollPane(jep);
    jsp.setPreferredSize(new Dimension(500,300));
    JOptionPane.showMessageDialog(
      null,
      jsp,
      "Information on the URL",
      JOptionPane.INFORMATION_MESSAGE);
  }
}
</sscce>

Example useage;
C:\showheader>javac ShowHeaders.java
C:\showheader>java ShowHeaders http://www.physci.org/pc/jtest.jnlp
C:\showheader>java ShowHeaders http://java.sun.com/
C:\showheader>rem: prompt user for an URL
C:\showheader>java ShowHeaders

HTH (anybody)

Andrew T.