DZone Snippets: servlet code

Basic WEBrick setup for local web server

ntk () — Tue, 17 Jun 2008 17:27:02 GMT

Put the following functions and aliases into your ~/.bash_login (or alternatives).





unset -f webrick_local



function webrick_local() { 



   declare root_dir="${HOME}/Desktop/www"



   /bin/mkdir -p "${root_dir}/WEBrickLog"

   /bin/chmod 0754 "${root_dir}" "${root_dir}/WEBrickLog"



   /usr/bin/touch "${root_dir}/WEBrickLog/webrick.pid" "${root_dir}/WEBrickLog/webrick_ruby.pid"

   /bin/chmod 0644 "${root_dir}/WEBrickLog/webrick.pid" "${root_dir}/WEBrickLog/webrick_ruby.pid"



#   /usr/bin/touch "${root_dir}/index.html"

#   /bin/chmod 0754 "${root_dir}/index.html"





/usr/local/bin/ruby <<-HEREDOC



   require 'webrick'

   require 'webrick/accesslog'

   include WEBrick



   require 'thread'

   require 'pp'



   root_dir = "${root_dir}"

   http_dir = File.expand_path(root_dir)



   File.open(http_dir + "/WEBrickLog/webrick_ruby.pid", "w") do |f|

      f.puts(Process.pid)

   end



   # cf. http://microjet.ath.cx/webrickguide/html/Logging.html

   webrick_log_file = File.expand_path(http_dir + "/WEBrickLog/webrick.log")

   #webrick_log_file = '/dev/null'  # disable logging

   webrick_logger = WEBrick::Log.new(webrick_log_file, WEBrick::Log::DEBUG)



   access_log_stream = webrick_logger

   access_log = [[ access_log_stream, WEBrick::AccessLog::COMBINED_LOG_FORMAT ]]



   system_mime_table = WEBrick::HTTPUtils::load_mime_types('/private/etc/httpd/mime.types.default')

   system_mime_table.store('rhtml', 'text/html')   # add a mime type for .rhtml files

   system_mime_table.store('php', 'text/html')

   system_mime_table.store('rb', 'text/plain')

   system_mime_table.store('pid', 'text/plain')

   #pp system_mime_table.sort_by { |k,v| k }



   server = WEBrick::HTTPServer.new(

     :BindAddress     =>    "localhost",

     :Port            =>    9090,

     :DocumentRoot    =>    http_dir,

     :FancyIndexing   =>    true,

     :MimeTypes       =>    system_mime_table,

     :Logger          =>    webrick_logger,

     :AccessLog       =>    access_log

   )



   server.config.store(:DirectoryIndex, server.config[:DirectoryIndex] << "default.htm")

   #pp server.config



   # cf. http://snippets.dzone.com/posts/show/5208

   class TimeServlet < HTTPServlet::AbstractServlet



      def do_GET(req, res)

         res['Content-Type'] = 'text/html'

         res.status = 200

         res.body = "Time: #{Time.now.to_s}" + "\n"

      end



      # cf. http://www.hiveminds.co.uk/node/244, published under the

      # GNU Free Documentation License, http://www.gnu.org/copyleft/fdl.html



      @@instance = nil

      @@instance_creation_mutex = Mutex.new



      def self.get_instance(config, *options)

         #pp @@instance

         @@instance_creation_mutex.synchronize { 

            @@instance = @@instance || self.new(config, *options) }

      end



   end





   # cf. http://ttripp.blogspot.com/2007/01/fun-with-http.html

   class PostDumper < WEBrick::HTTPServlet::AbstractServlet

  

      # Reload file for each request, instantly

      # updating the server with code changes 

      # without needing a restart.



=begin

      def PostDumper.get_instance( config, *options )

         load __FILE__

         PostDumper.new config, *options

      end

=end



      # cf. http://www.hiveminds.co.uk/node/244, published under the

      # GNU Free Documentation License, http://www.gnu.org/copyleft/fdl.html



      @@instance = nil

      @@instance_creation_mutex = Mutex.new



      def self.get_instance(config, *options)

         #pp @@instance

         @@instance_creation_mutex.synchronize { 

            @@instance = @@instance || self.new(config, *options) }

      end



      def do_GET( request, response )

         response.status = 200

         response['Content-Type'] = "text/plain"

         response.body = dump_request( request )

      end

  

      def do_POST( request, response )

         response.status = 200

         response['Content-Type'] = "text/plain"

         response.body = dump_request( request )

         response.body << request.body

      end

  

      def dump_request( request )

         request.request_line << "\r\n" <<

         request.raw_header.join( "" ) << "\r\n"

      end

   end



   server.mount("/dump", PostDumper)

   server.mount("/time", TimeServlet, {:FancyIndexing=>true})



   # handle signals

   %w(INT).each do |signal|

      trap(signal) { server.shutdown }

   end



   server.start



HEREDOC



return 0



}



export -f webrick_local



# start WEBrick alias

alias webrick='swr'



# start WEBrick

unset -f swr

function swr() {   

  declare webrick_pid_file="${HOME}/Desktop/www/WEBrickLog/webrick.pid"

  if [[ -e "${webrick_pid_file}" ]]; then echo "WEBrick already started!"; return 1; fi

  /bin/bash -c "webrick_local" &

  declare WEBRICKPID=$!

  mkdir -p "${HOME}/Desktop/www/WEBrickLog"

  echo $WEBRICKPID > "${HOME}/Desktop/www/WEBrickLog/webrick.pid"

  return 0

}

export -f swr



# quit WEBrick

unset -f qwr

function qwr() { 

   declare webrick_pid_file="${HOME}/Desktop/www/WEBrickLog/webrick.pid"

   declare webrick_ruby_pid_file="${HOME}/Desktop/www/WEBrickLog/webrick_ruby.pid"

   if [[ ! -e "${webrick_pid_file}" ]]; then echo "no such file: ${webrick_pid_file}"; return 1; fi

   declare PIDW=$(cat "${webrick_pid_file}" 2>/dev/null)

   declare PIDR=$(cat "${webrick_ruby_pid_file}" 2>/dev/null)

   kill -INT $PIDW 2>/dev/null || echo "no such PIDW: ${PIDW}"

   kill -INT $PIDR 2>/dev/null || echo "no such PIDR: ${PIDR}"

   rm -f "${webrick_pid_file}" "${webrick_ruby_pid_file}"

   return 0

}

export -f qwr



# quit WEBrick; cf. Job Control Commands, http://tldp.org/LDP/abs/html/x8816.html

###alias qwr='echo "quit WEBrick with ctrl-c ..."; fg %webrick 2>/dev/null'



alias openwww='/usr/bin/open http://localhost:9090'

alias wrlog='/usr/bin/open http://localhost:9090/WEBrickLog/webrick.log'





#----------------------------------------





source ~/.bash_login



webrick



openwww

wrlog

open http://localhost:9090 

open http://localhost:9090/WEBrickLog

open http://localhost:9090/WEBrickLog/webrick.log



open http://localhost:9090/time

open http://localhost:9090/dump



wrlog

qwr

Further information:

- WEBrick
- WEBrick RDoc
- What is WEBrick?
- Guide to using WEBrick for Rails development
- Dynamic WEBrick Servers in Ruby
- Gnome's Guide to WEBrick
- Running Servlets with WEBrick
- rsphandler
- URL rewriting with WEBrick

Ruby Servlets

jrobertson (James Robertson) — Mon, 10 Mar 2008 23:17:53 GMT

This WEBrick example demonstrates a basic servlet which displays the current time. Source code copied from At the Forge - Getting Started with Ruby [linuxjournal.com].



#!/sw/bin/ruby

require 'webrick'

include WEBrick



# ---------------------------------------------

# Define a new class

class CurrentTimeServlet

  < WEBrick::HTTPServlet::AbstractServlet



  def do_GET(request, response)

    response['Content-Type'] = 'text/plain'

    response.status = 200

    response.body = Time.now.to_s + "\n"

  end

end



# ----------------------------------------------

# Create an HTTP server

s = HTTPServer.new(

  :Port            => 8000,

  :DocumentRoot    => "/usr/local/apache/htdocs/"

)



s.mount("/time", CurrentTimeServlet)



# When the server gets a control-C, kill it

trap("INT"){ s.shutdown }



# Start the server

s.start

e.g. http://localhost:8001/time
output



Mon Mar 10 23:06:58 +0000 2008

Reference: http://www.webrick.org/

Example file download servlet

frost137 (Douglas Wyatt) — Tue, 09 Oct 2007 23:12:04 GMT

// description of your code here



  /**

     *  Sends a file to the ServletResponse output stream.  Typically

     *  you want the browser to receive a different name than the

     *  name the file has been saved in your local database, since

     *  your local names need to be unique.

     *

     *  @param req The request

     *  @param resp The response

     *  @param filename The name of the file you want to download.

     *  @param original_filename The name the browser should receive.

     */

    private void doDownload( HttpServletRequest req, HttpServletResponse resp,

                             String filename, String original_filename )

        throws IOException

    {

        File                f        = new File(filename);

        int                 length   = 0;

        ServletOutputStream op       = resp.getOutputStream();

        ServletContext      context  = getServletConfig().getServletContext();

        String              mimetype = context.getMimeType( filename );



        //

        //  Set the response and go!

        //

        //

        resp.setContentType( (mimetype != null) ? mimetype : "application/octet-stream" );

        resp.setContentLength( (int)f.length() );

        resp.setHeader( "Content-Disposition", "attachment; filename=\"" + original_filename + "\"" );



        //

        //  Stream to the requester.

        //

        byte[] bbuf = new byte[BUFSIZE];

        DataInputStream in = new DataInputStream(new FileInputStream(f));



        while ((in != null) && ((length = in.read(bbuf)) != -1))

        {

            op.write(bbuf,0,length);

        }



        in.close();

        op.flush();

        op.close();

    }

'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();

    }

}

Retrieving all Parameters to a Java Servlet

thitiv (Thiti V. Sintopchai) — Sat, 10 Feb 2007 13:16:54 GMT

//
// Ref: http://forum.java.sun.com/thread.jspa?threadID=405328&messageID=2184836
//
// The getParameterMap() returns a Map that has Strings as keys and String[] as
// values. That's so you can have ?x=1&x=2&x=3 in your URL query string. The
// keys in the Map must be unique but there can be multiple values for each
// key.
//
// So.. when you pull a value out of a Map created by the getParameterMap()
// method you must cast it to a String[] or else you'll get the value's
// location in memory instead of it's actual value. If you're writing the
// code and know for a fact that you'll always have only one value for each
// param then you can just use yourVar[0] but if there may be multiple
// values for each key then you'll need to loop over each value array.
//



    Map params = request.getParameterMap();

    Iterator i = params.keySet().iterator();

    

    while ( i.hasNext() )

      {

        String key = (String) i.next();

        String value = ((String[]) params.get( key ))[ 0 ];

      }

Simple Java Servlet

thitiv (Thiti V. Sintopchai) — Sat, 10 Feb 2007 10:08:12 GMT

// Simple Servlet Skeleton



package net.tvs.servlet;



import java.io.IOException;



import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;



import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;



public class MyServlet extends HttpServlet

{

  private static Log _logger = LogFactory.getLog( MyServlet.class );



  public void init(ServletConfig config) throws ServletException

  {

    super.init( config );

    try

      {

        // Initialization

      }

    catch ( Exception e )

      {

        _logger.fatal( e.getMessage() );

      }

    _logger.info( "MyServlet initialized" );

  }

  

  protected void doGet(HttpServletRequest request, HttpServletResponse response)

      throws ServletException, IOException

  {

    processRequest( request, response );

  }



  protected void doPost(HttpServletRequest request, HttpServletResponse response)

      throws ServletException, IOException

  {

    processRequest( request, response );

  }



  protected void processRequest(HttpServletRequest request,

      HttpServletResponse response) throws ServletException, IOException

  {

    response.setContentType( "text/html;charset=UTF-8" );

    String param = request.getParameter( "param" );

    _logger.debug( "Received param: " + param );



    // Implementation...



    PrintWriter out = response.getWriter();

    response.setContentType( "text/xml" );

    response.setHeader( "Cache-Control", "no-cache" );



    out.println( "" );

    out.println( "" + param + "" );

    out.println( "" );

    out.close();

  }



}

avoid web caching

remvee (Remco van 't Veer) — Mon, 25 Sep 2006 00:28:46 GMT



// Set to expire far in the past.

response.setHeader("Expires", "Sat, 6 May 1995 12:00:00 GMT");

// Set standard HTTP/1.1 no-cache headers.

response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");

// Set IE extended HTTP/1.1 no-cache headers (use addHeader).

response.addHeader("Cache-Control", "post-check=0, pre-check=0");

// Set standard HTTP/1.0 no-cache header.

response.setHeader("Pragma", "no-cache");

A Client For the XML-RPC Servlet

JohnMunsch (John Munsch) — Mon, 06 Mar 2006 01:50:55 GMT

// When combined with the Apache XML-RPC library this code
// will let you call the servlet in the snippet "An XML-RPC
// Servlet". Of course, since XML-RPC is pretty ubiquitous
// you can also use this code to call servers in dozens of
// other languages as well.



import java.util.Vector;



import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.apache.xmlrpc.XmlRpcClient;



public class XMLRPCTestClient {

    private static final String serverAddress = 

	"http://localhost:8080/lol/remoteapi";

    private static Log log = LogFactory.getLog(XMLRPCTestClient.class);

    

    /** Creates a new instance of XMLRPCTestClient */

    public XMLRPCTestClient(String address) {

        try {

            XmlRpcClient xmlrpc = new XmlRpcClient(address);



            Vector params = new Vector();

            params.addElement("Hello World! Hello!");



            try {

                // this method returns a string

                String result = (String) xmlrpc.execute("echo.echo", params);

                System.out.println(result);

            } catch (Exception e) {

                log.error("The remote procedure call failed.", e);

            }

        } catch (java.net.MalformedURLException mue) {

            log.error(

                "The address given for the XML-RPC interface is bad: " + address);

        }

    }



    /**

     * @param args the command line arguments

     */

    public static void main(String[] args) {

        XMLRPCTestClient xmlRPCTestClient = new XMLRPCTestClient(

            serverAddress);

    }

}