DZone Snippets: Mikewilsonuk's Code Snippets

'ant' build file for HelloWorldServlet and JettyLauncher

mikewilsonuk (Mike Wilson) — Sat, 02 Jun 2007 11:15:45 GMT

A pretty straightforward 'ant' build file. You will need to edit the jetty.home property to indicate where you installed Jetty.







  

  

  

  



  

    

    

    

  



  

    

    	classpathref="jetty.lib.path">

      

      

    

  



        description="Recompile from scratch"/>



  

    	classpathref="jetty.lib.path">

Minimal Java servlet

mikewilsonuk (Mike Wilson) — Sat, 02 Jun 2007 11:13:54 GMT

There is nothing particularly original here -- there are variations of this all over the place. This works nicely with my JettyLauncher class (see my other posts on DZone Snippets).





package com.babblemind;



import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.io.PrintWriter;



public class HelloWorldServlet extends HttpServlet{

    protected void doGet(HttpServletRequest httpServletRequest,

	HttpServletResponse httpServletResponse)

	    throws ServletException, IOException {



        httpServletResponse.setContentType("text/plain");

        PrintWriter out = httpServletResponse.getWriter();

        out.println("Hello World!");

        out.close();

    }

}

Minimal Jetty http server with Java servlet

mikewilsonuk (Mike Wilson) — Sat, 02 Jun 2007 11:11:50 GMT

This will start a Jetty http server with a single Java servlet at the root. See http://www.mortbay.org/ for Jetty downloads. This needs HelloWorldServlet from one of my other posts. Make life easier by downloading my ant build.xml as well.





package com.babblemind;



import org.mortbay.jetty.Server;

import org.mortbay.jetty.servlet.Context;

import org.mortbay.jetty.servlet.ServletHolder;



public class JettyLauncher {

    public static void main(String[] args) throws Exception {

	Server server = new Server(8080);    

	Context root = new Context(server, "/", Context.SESSIONS);

	root.addServlet(new ServletHolder(new HelloWorldServlet()), "/*");

	server.start();

    }

}

php image from database using PEAR::DB

mikewilsonuk (Mike Wilson) — Mon, 26 Mar 2007 08:16:22 GMT

This fetches an image from a MySQL database (I know, a database may not be the best place to keep images). The image is sent to the web client as an image/jpeg.



require_once 'DB.php';



define('DB_SERVER', 'localhost');

define('DB_USER', 'php');

define('DB_PASS', '');

define('DB_DATABASE', 'images');

define('DSN', 'mysql://'.DB_USER.':'.DB_PASS.'@'.DB_SERVER.'/'.DB_DATABASE);



global $db;

$db = DB::connect(DSN);



if (PEAR::isError($db)) {

    die($db->getMessage());

}



if (isset($_GET['id'])) {

  header('Content-Type: image/jpeg');

  $id = $_GET['id'];

  $sql = "select image_data from images where id = ?";

  $result =& $db->query($sql, $id);



  if (PEAR::isError($result)) {

    die($result->getMessage());

  } else {

    if ($result->fetchInto($row)) {

      echo $row[0];

    }

  }



} else {

  echo file_get_contents('broken.png');

}

?>

Very simple php file upload

mikewilsonuk (Mike Wilson) — Mon, 26 Mar 2007 08:00:34 GMT

I think this is the minimum necessary to upload a file in php. First, the form, index.php:





    

    Send this file:

Next, the php to accept the file, upload.php





$uploaddir = '/var/www/uploads/';

$uploadfile = $uploaddir . basename($_FILES['userfile']['name']);



echo "";



if (move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) {

  echo "File is valid, and was successfully uploaded.\n";

} else {

   echo "Upload failed";

}



echo "";

echo '';

echo 'Here is some more debugging info:';

print_r($_FILES);

print "";



?>

Add a jar file to Java load path at run time

mikewilsonuk (Mike Wilson) — Fri, 23 Feb 2007 15:24:18 GMT

Sometimes it is necessary to amend the class load path at run time. For example, dynamically adding jar files containing user-configurable JDBC data sources. The way this is done is truly monstrous -- the URL Path format was only revealed when a colleague looked into the Java library sources.



import java.net.URL;

import java.io.IOException;

import java.net.URLClassLoader;

import java.net.MalformedURLException;



public class JarFileLoader extends URLClassLoader

{

    public JarFileLoader (URL[] urls)

    {

        super (urls);

    }



    public void addFile (String path) throws MalformedURLException

    {

        String urlPath = "jar:file://" + path + "!/";

        addURL (new URL (urlPath));

    }



    public static void main (String args [])

    {

        try

        {

            System.out.println ("First attempt...");

            Class.forName ("org.gjt.mm.mysql.Driver");

        }

        catch (Exception ex)

        {

            System.out.println ("Failed.");

        }



        try

        {

            URL urls [] = {};



            JarFileLoader cl = new JarFileLoader (urls);

            cl.addFile ("/opt/mysql-connector-java-5.0.4/mysql-connector-java-5.0.4-bin.jar");

            System.out.println ("Second attempt...");

            cl.loadClass ("org.gjt.mm.mysql.Driver");

            System.out.println ("Success!");

        }

        catch (Exception ex)

        {

            System.out.println ("Failed.");

            ex.printStackTrace ();

        }

    }

}

Simple Ruby ActiveRecord example

mikewilsonuk (Mike Wilson) — Wed, 06 Dec 2006 15:57:18 GMT

Using Ruby ActiveRecord with an in-memory SQLite database. A nice simple example of this wonderful library.



require 'active_record'



ActiveRecord::Base.logger = Logger.new(STDERR)

ActiveRecord::Base.colorize_logging = false



ActiveRecord::Base.establish_connection(

    :adapter => "sqlite3",

    :dbfile  => ":memory:"

)



ActiveRecord::Schema.define do

    create_table :albums do |table|

        table.column :title, :string

        table.column :performer, :string

    end



    create_table :tracks do |table|

        table.column :album_id, :integer

        table.column :track_number, :integer

        table.column :title, :string

    end

end



class Album < ActiveRecord::Base

    has_many :tracks

end



class Track < ActiveRecord::Base

    belongs_to :album

end



album = Album.create(:title => 'Black and Blue',

    :performer => 'The Rolling Stones')

album.tracks.create(:track_number => 1, :title => 'Hot Stuff')

album.tracks.create(:track_number => 2, :title => 'Hand Of Fate')

album.tracks.create(:track_number => 3, :title => 'Cherry Oh Baby ')

album.tracks.create(:track_number => 4, :title => 'Memory Motel ')

album.tracks.create(:track_number => 5, :title => 'Hey Negrita')

album.tracks.create(:track_number => 6, :title => 'Fool To Cry')

album.tracks.create(:track_number => 7, :title => 'Crazy Mama')

album.tracks.create(:track_number => 8,

    :title => 'Melody (Inspiration By Billy Preston)')



album = Album.create(:title => 'Sticky Fingers',

    :performer => 'The Rolling Stones')

album.tracks.create(:track_number => 1, :title => 'Brown Sugar')

album.tracks.create(:track_number => 2, :title => 'Sway')

album.tracks.create(:track_number => 3, :title => 'Wild Horses')

album.tracks.create(:track_number => 4,

    :title => 'Can\'t You Hear Me Knocking')

album.tracks.create(:track_number => 5, :title => 'You Gotta Move')

album.tracks.create(:track_number => 6, :title => 'Bitch')

album.tracks.create(:track_number => 7, :title => 'I Got The Blues')

album.tracks.create(:track_number => 8, :title => 'Sister Morphine')

album.tracks.create(:track_number => 9, :title => 'Dead Flowers')

album.tracks.create(:track_number => 10, :title => 'Moonlight Mile')



puts Album.find(1).tracks.length

puts Album.find(2).tracks.length



puts Album.find_by_title('Sticky Fingers').title

puts Track.find_by_title('Fool To Cry').album_id

Very simple script using Dojo widget and I/O

mikewilsonuk (Mike Wilson) — Tue, 17 Oct 2006 18:46:31 GMT

Dojo is a Java Script toolkit. This is a minimal HTML page which uses a widget and talks to the server. This is based on the Dojo tutorial at JotSpot.







  Dojo: Hello World!



  



  







  

  




  

    Please enter your name:

Very basic lighttpd configuration

mikewilsonuk (Mike Wilson) — Tue, 17 Oct 2006 18:44:34 GMT

The configuration of lighttpd is vast and complex. Here is a close to minimal configuration which allows for Perl and Ruby CGI.



server.document-root = "/opt/lighttpd/htdocs"



server.port = 3000



mimetype.assign = (

  ".html" => "text/html",

  ".txt" => "text/plain",

  ".jpg" => "image/jpeg",

  ".png" => "image/png"

)



static-file.exclude-extensions = ( ".rb", ".pl", ".fcgi", ".php", ".rb", "~", ".inc" )

index-file.names = ( "index.html" )

server.modules += ( "mod_cgi" )



cgi.assign = (  ".rb" => "/opt/ruby/bin/ruby",

                ".pl" => "/usr/bin/perl")

Very basic Ruby XML parse

mikewilsonuk (Mike Wilson) — Thu, 03 Aug 2006 16:11:13 GMT

Tiny code fragment which loads configuration options from an XML file.



require "rexml/document"



doc = REXML::Document.new File.new("dbiconfig.xml")

configuration = doc.elements["configuration"]

database = configuration.elements["database"]

url = database.elements["url"].attributes["value"]

puts url