Social networks
You can find me on:
   
Open sharing content

These articles are available under Creative Commons license BY-SA-3.0

Posts Tagged ‘script’

Yeah, once again another HelloWorld stuff on the web. I was just curious to try to execute a Main class with an Ant script and found out that I couldn´t find the straight working snippets online easily, because I couldn´t get to know how to set the classpath. So I have wasted some minutes to make it work.

Let´s consider a little more than the classic HelloWorld example and pass a command line parameter as well:

package de.demo;

public class HelloWorld {

public static void main(String[] args) {
System.out.println("Hello Main! \n"  + "Parameter: "+ args[0]);
}

}

Then run following build.xml script:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<project basedir="." default="run" name="Ant Hello World">
	
	<property name="src" value="." />

	<path id="classpath">
		<fileset dir="${src}">
		</fileset>
	</path>

	<target name="compile">
		<javac srcdir="." />
	</target>

	<target name="run" depends="compile">
		<!-- Print directly in the console -->
		<echo message="Hello World!" />
		<!-- Run main class with parameters-->
		<java classname="de.demo.HelloWorld">
			<arg value="10"/>
			<classpath refid="classpath">
			</classpath>
		</java>
	</target>

</project>

In the console you will see something like:

Buildfile: C:\Users\liparulol\workspace\AntDemos\buildHelloWorld.xml
compile:
[javac] C:\Users\liparulol\workspace\AntDemos\buildHelloWorld.xml:14: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds
[javac] Compiling 1 source file
run:
[echo] Hello World!
1 Hello Main!
1 Parameter10
BUILD SUCCESSFUL
Total time: 745 milliseconds

That´s it!

Library FOR WWW in Perl (LWP)

In Linux you can istall all the perl modules about the web (LWP, URI, URL, HTTP…) at once:

:~$ sudo apt-get install libwww-perl

LWP is the most used Perl module for accessing data on the web.

LWP::Simple – module to get document by http
its functions don’t support cookies or authorization, setting header lines in the HTTP request; and generally, they don’t support reading header lines in the HTTP response (most notably the full HTTP error message, in case of an error). To get at all those features, you’ll have to use the LWP::UserAgent;

LWP::UserAgent is a class for “virtual browsers,” which you use for performing requests, and HTTP::Response is a class for the responses (or error messages) that you get back from those requests.

There are two objects involved: $browser, which holds an object of the class LWP::UserAgent, and then the $response object, which is of the class HTTP::Response. You really need only one browser object per program; but every time you make a request, you get back ar esponse object, which will have some interesting attributes:

$response->is_success : A HTTP status line, indicating success or failure  (like “404 Not Found”).

$response->content_type A MIME content-type like “text/html”, “image/gif”, “application/xml”, and so on, which you can see with

$response->content : the actual content of the response. If the response is HTML, that’s where the HTML source will be; if it’s a GIF, then $response->content will be the binary GIF data.

Enabling Cookies

A default LWP::UserAgent object acts like a browser with its cookies support turned off.
You can even activate cookies, with the following function:

$browser->cookie_jar({});

with “cookie_jar” you can get and save the cookies from Browsers.

The following script gets a url from the shell and print the content of the corresponding web page both to screen and a new file called “code.html” (created by running the script).

———————————————————-webclient.pl———————————–

#!/usr/bin/perl -w
use LWP::UserAgent;

#browser = instance of the UserAgent class
my $browser = LWP::UserAgent->new;
my $url =$ARGV[0]; # passing the url by command line
my $response = $browser->get($url);

die "Can’t get $url \n", $response->status_line
unless $response->is_success;

# check if the content is html
die "Hey, I was expecting HTML, not ", $response->content_type
unless $response->content_type eq 'text/html';

print "Page content: \n";

#print content to console
print $response->decoded_content;

#print content to a NEW file
open (MYPAGE, '>>code.html');
print MYPAGE $response->decoded_content;
close (MYPAGE);

#REGULAR EXPRESSION: search for a string in the content
if($response->content =~ m/perl/i) {
print " \n \n This page is about Perl!\n \n";
} else {print "\n \n No content about Perl! \n \n"; }

Let’s analyze the following perl scripta “cinema.pl”, to create and populate a simple database about  movies, and “query_hollywood.pl” to execute a simple SELECT-FROM-WHERE query on it.

—————————————cinema.pl————————————————————

#!/usr/bin/perl -w

use DBI;
use strict;

# CONFIG VARIABLES
my $platform = “SQLite”;
my $database = “hollywood.db”;
my $host = “localhost”;
my $port = “3306”;
my $user = “username”;
my $pw = “password”;

# DATA SOURCE NAME
my $dsn = “dbi:$platform:$database:$host:$port”;

# PERL DBI CONNECT
my $dbh = DBI->connect($dsn, $user, $pw) or die “Cannot connect: $DBI::errstr”;

# creating the “hollywood” database
$dbh->do(“CREATE TABLE IF NOT EXISTS actors(aid integer primary key, name text)”);

$dbh->do(“CREATE TABLE IF NOT EXISTS  movies(mid integer primary key, title text)”);

$dbh->do(“CREATE TABLE IF NOT EXISTS actors_movies(id integer primary key, mid integer, aid integer)”);

#populating “actors” table
$dbh->do(“INSERT INTO actors(name) VALUES(‘Philip Seymour Hofman’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Kate Shindle’)”);
$dbh->do(“INSERT INTO actors(name) VALUES (‘Kelci Stephenson’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Al Pacino’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Gabrielle Anwar’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Patricia Arquette’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Gabriel Byrne’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Max von Sydow’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Ellen Burstyn’)”);
$dbh->do(“INSERT INTO actors(name) VALUES(‘Jason Miller’)”);

#populating “movies” table

$dbh->do(“INSERT INTO movies VALUES(1,’Capote’)”);
$dbh->do(“INSERT INTO movies VALUES(2,’Scent of a woman’)”);
$dbh->do(“INSERT INTO movies VALUES(3,’Stigmata’)”);
$dbh->do(“INSERT INTO movies VALUES(4,’Exorcist’)”);
$dbh->do(“INSERT INTO movies VALUES(5,’Hamsun’)”);

#populating “actorsMovies” table
$dbh->do(“INSERT INTO actors_movies VALUES(1,1,1)”);
$dbh->do(“INSERT INTO actors_movies VALUES(2,2,1)”);
$dbh->do(“INSERT INTO actors_movies VALUES(3,3,1)”);
$dbh->do(“INSERT INTO actors_movies VALUES(4,4,2)”);
$dbh->do(“INSERT INTO actors_movies VALUES(5,5,2)”);
$dbh->do(“INSERT INTO actors_movies VALUES(6,6,3)”);
$dbh->do(“INSERT INTO actors_movies VALUES(7,7,3)”);
$dbh->do(“INSERT INTO actors_movies VALUES(8,8,4)”);
$dbh->do(“INSERT INTO actors_movies VALUES(9,9,4)”);
$dbh->do(“INSERT INTO actors_movies VALUES(10,10,4)”);
$dbh->do(“INSERT INTO actors_movies VALUES(11,8,5)”);

print qq{“Hollywood” database created! \n };

$dbh->disconnect;

—————————————————query_hollywood.pl———————————————

#!/usr/bin/perl -w

use DBI;
use strict;

# CONFIG VARIABLES
my $platform = “SQLite”;
my $database = “hollywood.db”;
my $host = “localhost”;
my $port = “3306”;
my $user = “username”;
my $pw = “password”;

# DATA SOURCE NAME
my $dsn = “dbi:$platform:$database:$host:$port”;

# PERL DBI CONNECT
my $dbh = DBI->connect($dsn, $user, $pw) or die “Cannot connect: $DBI::errstr”;

# EXECUTE THE QUERY
my $query = “SELECT actors.name , movies.title  FROM actors,movies,actors_movies WHERE actors.aid=actors_movies.aid and
movies.mid=actors_movies.mid”;

my $sth=$dbh->selectall_arrayref($query);

print “Actor                                                          Movie \n” ;
print “======================  ====================\n”;

foreach my $row (@$sth) {
my ($name, $title) = @$row;

### Print out the table metadata…
printf “%-23s %-23s \n”, $name, $title;

}

$dbh->disconnect;

—————————————————————————————–

Make the perl scripts executable like:
$ sudo chmod +x script.pl

And run them liket:
$ ./script.pl

The result of the query is:

Actor                                   Movie
====================  ====================
Philip Seymour Hofman     Capote
Philip Seymour Hofman     Scent of a woman
Philip Seymour Hofman     Stigmata
Kate Shindle                      Exorcist
Kate Shindle                      Hamsun

 

Very nice script, isn’t it?
I guess the DBI deserves further attention…